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Accelerating the Transfer of Wheat
Breeding Gains to Farmers: A Study of the
Dynamics of Varietal Replacement
edited by: PAUL W. HEISEY
with contributions from
M. RAMZAN AKHTER
M. ASLAM CHAUDHRY
ASLAM KHAN KHATTAK
CIMMYT is an internationally funded, nonprofit scientific research and training
organization. Headquartered in Mexico, the Center is engaged in a worldwide
research program for maize, wheat, and triticale, with emphasis on improving the
productivity of agricultural resources in developing countries. It is one of 13
nonprofit international agricultural research and training centers supported by the
Consultative Group on International Agricultural Research (CGIAR), which is
sponsored by the Food and Agriculture Organization (FAO) of the United Nations,
the International Bank for Reconstruction and Development (World Bank), and the
United Nations Development Programme (UNDP). The CGIAR consists of a
combination of 40 donor countries, international and regional organizations, and
CIMMYT receives core support through the CGIAR from a number of sources,
including the international aid agencies of Australia, Austria, Brazil, Canada, China,
Denmark, the Federal Republic of Germany, Finland, France, India, Iran, Ireland,
Italy, Japan, Mexico, the Netherlands, Norway, the Philippines, Spain, Switzerland,
the United Kingdom, and the USA, and from the European Economic Commission,
Ford Foundation, Inter-American Development Bank, UNDP, and World Bank.
CIMMYT also receives non-CGIAR extra-core support from Belgium, the Rockefeller
Foundation, and many of the core donors listed above.
Responsibility for this publication rests solely with CIMMYT.
Correct citation: Heisey, P.W. (ed.) 1990. Accelerating the Transfer of Wheat
Breeding Gains to Farmers: A Study of the Dynamics of Varietal Replacement in
Pakistan. CIMMYT Research Report No. 1. Mexico, D.F.: Mexico.
ISBN-968-6127-40-2 Printed in Mexico
xii Executive Summary
1 1 Introduction
Paul W. Heisey
5 2 Wheat Varietal Diversification over Time and Space as
Factors in Yield Gains and Rust Resistance in the Punjab
Derek Byerlee and Paul W. Heisey
25 3 Identifying Wheat Varieties Grown in Pakistan
Paul W. Heisey, M. Ramzan Akhter, Khaleel A. Tetlay,
Zulfiqar Ahmed, Munir Ahmad, Abdus Sattar,
Aslam Khan Khattak, and Muhammad Sharif
34 4 Wheat Seed Production and
Marketing in the Punjab and NWFP
M. Aslam Chaudhry, Paul W. Heisey, and Munir Ahmad
52 5 Farmers' Seed Sources and Seed Management
Khaleel A. Tetlay, Paul W. Heisey, Zulfiqar Ahmed,
and Munir Ahmad
65 6 Farmer Characteristics, Varietal Choice,
and the Spread of New Wheat Releases
Paul W. Heisey, Khaleel A. Tetlay, Zulfiqar Ahmed,
and Munir Ahmad
84 7 Conclusions
Paul W. Heisey
2 Figure 1.1 Survey areas, Pakistan.
4 Figure 1.2 Analysis of the system.
6 Figure 2.1 Factors influencing the number of years between varietal
14 Figure 2.2 Percentage of wheat area sown to major varieties, Punjab,
14 Figure 2.3 Percentage wheat area sown to other varieties, Punjab,
15 Figure 2.4 Wheat varietal replacement in the Yaqui Valley, Mexico,
16 Figure 2.5 Weighted average age of varieties and percentage area sown to
new varieties, Punjab, Pakistan, 1978-87.
39 Figure 4.1 Certified seed production and varietal diffusion for four
54 Figure 5.1 Seed sources for varieties currently planted.
56 Figure 5.2 Initial seed sources for new varieties.
71 Figure 6.1 Cumulative dates of planting by wheat varietal group in rice
zone, cotton zone, and Mardan, Pakistan.
7 Table 2.1 Target varietal replacement to meet farmers' minimum
requirements for yield increases (MRR = 100%).
8 Table 2.2 Duration of resistance in wheat varieties to stripe and leaf
rusts, Punjab, Pakistan, 1984.
9 Table 2.3 Proportion of wheat area sown to given varieties at five-year
intervals (hypothetical data).
12 Table 2.4 Varieties released since 1965 and year banned for rust
susceptibility, Punjab, Pakistan.
12 Table 2.5 Release of wheat varieties in the Punjab, 1955-84.
13 Table 2.6 Rate of varietal release in Pakistan and other countries.
13 Table 2.7 Extent and rate of diffusion of wheat varieties released in the
17 Table 2.8 Indices of wheat varietal replacement in the Punjab of
Pakistan, the Punjab of India, and northwestern Mexico,
18 Table 2.9 Measures of exposure of the wheat crop to a rust epidemic in
the Punjab in recent years.
19 Table 2.10 Percentage of total wheat area sown to a major variety at the
farm level, 1985/86.
20 Table 2.11 Regression results for vintage model for ISWYN data,
21 Table 2.12 Regression results for vintage model for normal season wheat
varieties, Khanewal Seed Farm variety x planting date trial,
22 Table 2.13 Estimates of annual wheat yield gains (%/yr) due to varietal
improvement, ISWYN, Faisalabad, 1965-86.
22 Table 2.14 Estimates of annual wheat yield gains (%/yr) due to varietal
improvement, Khanewal Seed Farm, Pakistan, 1980-86.
28 Table 3.1 Estimates of percentage area planted to major wheat varieties
in three zones of Pakistan, survey of farmers and breeders'
30 Table 3.2 Percentage area planted to major wheat varieties in the
Punjab, 1985/86 and 1986/87.
30 Table 3.3 Percentage area planted to major wheat varieties in the rice-
wheat survey area, 1985-89.
30 Table 3.4 Percentage area planted to major wheat varieties in the cotton-
wheat survey area, 1985-89.
31 Table 3.5 Changes in the percentage area of recommended and other
wheat varieties, rice zone, Pakistan, 1985-89.
32 Table 3.6 Changes in the percentage area of recommended and other
wheat varieties, cotton zone, Pakistan, 1985-89.
32 Table 3.7 Changes in the percentage area of recommended and other
wheat varieties, Mardan, Pakistan, 1985-88.
34 Table 4.1 Wheat seed sold in Punjab Province during the Agricultural
Development Corporation period, 1965-73.
36 Table 4.2 Production of basic wheat seed at Punjab Seed Corporation
38 Table 4.3 Certified wheat seed production (tons), Punjab, Pakistan.
44 Table 4.4 Procurement and sale of Punjab Seed Corporation wheat seed
46 Table 4.5 Prices and costs of wheat seed (Rs/90-kg bag), Punjab,
48 Table 4.6 Wheat seed (tons) procured and distributed in NWFP by the
Agricultural Development Authority.
49 Table 4.7 Price of certified wheat seed, NWFP.
52 Table 5.1 Seed depot density (retail seed outlets per 100,000 ha of
55 Table 5.2 Sources of wheat seed of new varieties and other popular
varieties currently planted, rice zone.
55 Table 5.3 Sources of wheat seed of new varieties and other popular
varieties currently planted, cotton zone.
55 Table 5.4 Sources of wheat seed of new varieties and other popular
varieties currently planted, Mardan.
Farm size and percentage farmers using new varieties who
initially got wheat seed from seed depot/research/extension.
Type of farmer from whom seed of new wheat variety was
Distance to farmers providing seed of new wheat varieties.
Percentage of farmers who knew seed depot location and had
visited a depot.
Variables used in probit analysis of knowledge of seed depot
location and visits to seed depot.
Factors related to correct knowledge of seed depot location,
Factors related to visits to seed depot, probit analysis.
Farmers' seed management practices for retained wheat seed.
Farmers' awareness and adoption of new wheat varieties.
Farmers' awareness of the rust problem.
Farmers' reasons for adopting new wheat varieties.
Farmers' reasons for planting both old and new wheat
Farmers' perceptions of wheat varietal characteristics, rice
Farmers' perceptions of wheat varietal characteristics, cotton
Farmers' perceptions of wheat varietal characteristics,
Variables used in probit analysis of awareness and adoption of
new wheat varieties.
Sources of information about new wheat varieties, from
farmers planting them.
Factors affecting awareness of new wheat varieties, probit
Factors affecting adoption of new wheat varieties by farmers
aware of them, probit analysis.
The authors wish to express their appreciation to Mubarik Ali, the late Mian M.
Aslam, M.A. Bajwa, Jose Crossa, Greg Edmeades, N.I. Hashmi, Tariq Husain,
Allaudin Khan, Larry Morgan, Melinda Smale, and Forrest Walters. The editor is
particularly grateful to John Brennan, Derek Byerlee, Kelly Cassaday, Jesse Dubin,
Peter Hobbs, and Jim Longmire, who read the manuscript in its entirety and made
many helpful suggestions. Funding from the United States Agency for International
Development under contracts 391-0489 and 394-0491, the Pakistan Agricultural
Research Council, and the World Bank in conducting the studies reported in
Chapters 3 to 6 is also gratefully acknowledged.
ADA Agricultural Development Authority
ADC Agricultural Development Corporation
AERU Agricultural Economics Research Unit
CDRI Cereal Disease Research Institute
CIMMYT Centro Internacional de Mejoramiento de Maiz y Trigo
International Maize and Wheat Improvement Center
CRS Crop Reporting Service
FSCD Federal Seed Certification Department
ISWYN International Spring Wheat Yield Nursery
MINFA Ministry of Food and Agriculture
NUWYT National Uniform Wheat Yield Trial
NWFP North West Frontier Province
PAD&SC Punjab Agricultural Development and Supplies Corporation
PARC Pakistan Agricultural Research Council
PERI Punjab Economic Research Institute
PSC Punjab Seed Corporation
This publication is the first in a new series of reports that document specific
CIMMYT research efforts. This series is directed toward technical audiences, and
each publication synthesizes the results of research that has usually occurred over
an extended period. Although this series will normally feature the research of
CIMMYT staff alone, collaborative research is sometimes reported. Such is the case
with this Report, which describes work done by Dr. Paul Heisey and Dr. Derek
Byerlee in conjunction with colleagues in Pakistan. Their investigation focused on
slow wheat varietal replacement and related problems that have gradually increased
the risk of serious rust epidemics in Pakistan.
The issues analyzed here initially came to the attention of researchers when they
began to conduct diagnostic surveys of the farming systems of Pakistan. Special
follow-up surveys to understand the problem of slow varietal replacement recorded,
for the first time, data on the sources of the seed that farmers grew, on how farmers
gained access to sources of seed, and on how they managed wheat seed once they
obtained it. Additional surveys identified which varieties farmers actually planted
and explored farmers' motives for changing varieties. Part of the analysis of the
survey results required that researchers develop a model for determining optimum
rates of varietal replacement. This analysis of the informal seed system was
complemented by a study of the formal system for breeding, producing, and
distributing seed in the Punjab and North West Frontier Province.
This report moves from the interpretation of survey results to an exploration of
numerous organizational issues impinging on efforts to improve rates of varietal
replacement. By showing just how the processes of breeding, seed production, seed
distribution, information transfer, and adoption of new varieties function in
Pakistan, and by indicating how more appropriate policies could make these
processes more efficient, the authors reveal both the complexity and urgency of the
varietal replacement problem. It is anticipated that this study, whose methods and
results are relevant beyond the borders of Pakistan, will enhance the ability of
developing world research, seed, and extension systems, as well as farmers, to
translate the gains achieved in plant breeding research into the economic benefits
associated with more efficient and more stable crop production.
MUNIR AHMAD is a rural sociologist in charge of the Agricultural Economics Research
Unit of PARC in Tarnab, NWFP.
ZULFIQAR AHMED is an economist with the Agricultural Economics Research Unit of
PARC in Faisalabad, Punjab.
M. RAMZAN AKHTER is a PhD student in economics at the University of
Minnesota in St. Paul. He was previously in charge of the Agricultural
Economics Research Unit of PARC in Faisalabad, Punjab.
DEREK BYERLEE is an economist at CIMMYT, Mexico. His contribution to this
publication is the result of research he conducted when he was based in
Pakistan as the regional economist for CIMMYT's South Asian research
M. ASLAM CHAUDHRY is an economist with the Economic Analysis Network, Ministry
of Agriculture, Islamabad. He was previously with the Punjab Seed Corporation.
PAUL W. HEISEY is an economist with CIMMYT in Malawi. His contribution to this
report is the product of his work in Pakistan from 1985 to 1988 with the CIMMYT
ASLAM KHAN KHA'TfAK is a wheat breeder at the Cereal Crops Research
Institute, Pirsabak, and is currently a PhD student in breeding at the
University of North Dakota.
ABDUS SATTAR is a wheat breeder a the Wheat Research Institute, Ayub
Agricultural Research Institute, Faisalabad.
MUHAWMMAD SHARIF is an economist in charge of the Agricultural Economics Research
Unit of PARC in Faisalabad.
KHALEEL TETLAY is associate program economist with the Aga Khan Rural Support
Programme in Gilgit, Northern Areas.
M Executive Summary
In wheat growing areas, slow replacement of older varieties with newer ones in
farmers' fields delays the transfer of benefits from breeding research to farmers and
heightens the risk of disease epidemics, especially when the diversity of varieties in
an area is limited. Determining the optimal time period in which farmers should
replace older varieties and understanding which factors in the seed system may
impede rapid varietal replacement are vital to bringing the gains of breeding
research to farmers' fields.
During the post-Green Revolution period, yield gains attained in wheat through
genetic improvement have been about 0.75% per year, although there is a certain
variability around trend. At this rate of yield gain it will pay farmers to change
varieties every four years, given reasonable assumptions about current levels of
many of the parameters influencing their choices. Differences in microenvironments,
different lengths of time between periods of actual yield gains, and fluctuations in
observable rust losses mean that in some cases the desired period for farmers to
change varieties could be longer.
In Pakistan since the Green Revolution in wheat, varietal replacement has been slow
compared to areas with similar ecological circumstances, such as the Punjab of India
and northwestern Mexico. Furthermore, wide areas in Pakistan are often dominated
by a single variety and diversity occurs only during the transition from one dominant
variety to another. In the Punjab from 1977 to 1986, the proportion of wheat area
planted to varieties that are no longer recommended because of rust susceptibility
averaged over 40%, and from 1982 to 1986 the area planted to varieties with leaf rust
ratings of 50S or higher was nearly 60% of the total area. Apart from the losses that
could be caused by an epidemic, annual losses in yield to rust are also serious. They
are not widely reported but may add up to a substantial annual loss.
To examine the dynamics of the varietal replacement problem in Pakistan, four
complementary studies were designed to analyze the wheat varietal and seed system
from the breeding of new lines to adoption by farmers. The studies focus on the
Punjab, which contains 71% of Pakistan's total wheat area and 75% of all the
irrigated wheat area in Pakistan, because relatively more data are available and the
seed system is most developed. Both the methods and results of this research should
be useful to researchers outside of Pakistan who are seeking a framework for
analyzing the interrelated problems of slow varietal replacement, limited varietal
diversity, and ineffective seed systems.
The first study examines the problem of slow varietal replacement from the
perspective of the research system. It considers measures of varietal replacement
and spatial diversification and applies them to the Punjab. These measures are used
to investigate whether there is an optimal rate of varietal replacement and to assess
the level of disease exposure. Other measures for assessing the progress of a wheat
breeding program are also presented, including the rate of release of new varieties
and the rate of yield gain over time attributable to the development of new varieties.
It appears that in the Punjab varietal replacement has been much slower than a
reasonable target-once every five or six years-and the area planted to rust
susceptible varieties has been unacceptably high (over 50% of the Punjab's wheat
area in the first half of the 1980s).
The second study assesses problems in obtaining basic data on the area covered by
different varieties. Since varietal monitoring competes with many other agricultural
data collection needs, any large scale estimation of varietal coverage is likely to be a
byproduct of surveys designed for other purposes. Physical identification of varieties
by skilled personnel is quite expensive, so usually identification depends on the
statements of farmers, who may not always know varietal names or may identify
cultivars incorrectly. Cluster sampling designs tend to create large standard errors
in estimates of varietal coverage because variances within the primary sampling
units (e.g. villages) tend to be lower than variances across the primary units.
The third study concentrates on seed multiplication and marketing by the Punjab
Seed Corporation (PSC). Data are presented on past and current seed production and
the present seed marketing network in the Punjab. The PSC has effected a clear
increase in production capacity for wheat seed in the Punjab. In the late 1960s and
early 1970s, before the PSC was established, on average only a little more than
16,000 t of seed were sold each year. In the five years after it was established, the
PSC raised production from 4,000 to 44,000 t, where it has remained since. Even in
North West Frontier Province (NWFP), where there is no specialized seed production
industry, the ability to produce wheat seed has advanced: the Agricultural
Development Authority (ADA) in NWFP procures 3,000-4,000 t/yr. Formerly much of
this seed came from the Punjab; in 1986/87 all of it came from NWFP.
Major problems remain in planning seed production and in promoting and marketing
seed. The early stages of seed multiplication could be speeded up, but the seed
authorities cannot be sure which varieties to multiply. Production is not expanded
because the PSC cannot sell the additional seed that is procured. The goal for
marketing wheat seed appears to be to supply pure certified seed to farmers, rather
than to facilitate the rapid replacement of varieties. The evidence suggests that
farmers use the formal seed system more to change varieties than to get new seed of
varieties they already grow. Nevertheless, an active seed network, closely linked
with both agricultural research and extension, is a prerequisite for more rapid
varietal replacement in the post-Green Revolution period.
The commission paid to private dealers for handling seed is much less than for
fertilizer, an input in greater and more regular demand. Hence seed is the input
whose distribution at the farm level is still largely handled by the public sector. Very
little effort is made by the seed industry to promote its product.
Greater promotional effort, a wider distribution network, and higher commissions to
dealers are necessary to spread new seed more rapidly. These changes will probably
require an increase in seed price. Though higher seed prices will reduce farmers'
demand for seed in the short term, the net effect could be more rapid varietal
replacement if higher prices lead to more promotion and a better distribution
network, and so reduce the amount of time before new varieties reach the farmers.
The Punjab of India has both higher wheat seed prices and faster varietal
replacement than the Punjab of Pakistan.
The fourth study concentrates on farmers' perceptions. Just one-quarter to one-half
of farmers sampled in three major cropping systems thought some wheat varieties
were more disease resistant than others. Only one-quarter or fewer farmers thought
resistant varieties could lose their resistance.
Farmers' awareness of new wheat varieties was best explained in the rice-wheat
zone of the Punjab, where the diffusion of new varieties has proceeded the farthest.
In this zone awareness of new wheat varieties is positively influenced by education,
extension contact, and location in a village where many fields are planted to new
varieties. Some of these variables, notably education or literacy, as well as village
factors, are influential in the other surveyed zones, the Punjab cotton-wheat area
and irrigated Mardan, NWFP.
In the presence of other variables, farm size usually becomes a less significant
determinant of varietal awareness or adoption in areas where new varieties have
spread the farthest. Smaller farmers will adopt new varieties once they are aware of
them, but large farmers are more likely to become aware earlier because of their
higher literacy and better contact with extension and other sources of information.
One noticeable way in which farm size is important in all areas is that large farmers
are more likely to plant both old and new varieties rather than to specialize in one or
the other. Small farmers who do adopt a new variety are more likely to plant all
their wheat area to that variety.
Yield was by far the most common reason stated by farmers in all three zones for
changing varieties. Most farmers simply believed that the yield of the new variety
was superior, although a few farmers related this perceived yield advantage to
reduced yield in their old varieties because of disease or other factors. In
multivariate analysis, farmers' perception that new varieties yield better is usually
the strongest factor influencing adoption. Performance at late planting dates is also
important, particularly in the cotton zone.
In the three sampled areas in 1985/86, when all the sampled farmers' wheat fields
were considered, 50-60% were planted with retained seed. An additional 20-30'
were planted with seed obtained from neighboring farmers. Farmer-to-farmer
transfer is clearly a major method of varietal diffusion. Some 45-55% of the farmers
in all three zones who were planting post-1978 releases initially got seed from other
wl.v. ^ ^ ^
farmers. Of farmers planting new varieties, over 33% in the rice-wheat zone, 50% in
the cotton-wheat zone, but only 14% in Mardan initially got seed from the depot.
In all three zones, literacy and extension contact were the two variables most likely
to be related significantly and positively to correct knowledge of where the seed
depot was located. Distance from the seed depot may have been related negatively in
the Punjab to knowledge of the depot's location. In the Punjab, farmers aware of new
varieties were also more likely to be aware of the seed depot; in NWFP there was no
relationship, confirming the relative lack of importance of the seed depot in Mardan
in spreading new varieties.
Only 40-50% of the farmers in all three zones who used their own seed managed it
through techniques such as selecting a special field or threshing seed separately
from grain. Very few significant relationships existed between farmer characteristics
and seed management.
Extension contact was not very important in explaining awareness and adoption of
new varieties. Varietal demonstrations by the extension service have probably not
been spread widely enough and have not always been tailored to different
agroecological circumstances or cropping system constraints. The promotional efforts
of research, the seed industry, and extension have not been well coordinated.
Taken together, the results of all four studies emphasize the importance of regular
varietal replacement for farmers and for the nation of Pakistan. The methods used in
this research-institutional analysis, analysis of research data, and farmer
surveys-offer a means to evaluate the complex relationships between wheat
breeding, varietal testing, and release; seed production and distribution; extension;
government policy; and varietal change at the farmer level. Although the conclusions
presented in this report are specific to a particular crop, place, and time, they may
also be viewed as hypotheses that in some cases might be applicable in different
situations, perhaps after modification.
Future studies to expand knowledge of factors relating to varietal replacement might
develop methods for determining rough objectives for the number and genetic
diversity of varieties to be released by mature plant breeding programs in countries
with large areas planted to the crop in question. More case studies of seed systems
with different degrees of success in marketing seed of different crops would also be
useful. Such studies do exist; what is needed is to add the perspective of varietal
replacement to the legal and institutional description they often contain. Additional
research is also required to verify empirically the relative strengths of the factors
influencing farmers' demand for replacement seed. Finally, studies of other countries
and particularly of other crops would sharpen our understanding of the features of
varietal replacement that are universal and of the changes in assumptions and
methods necessary to analyze factors more specific to time, place, and particular
En las zonas productoras de trigo, la sustituci6n lenta de las variedades mas viejas
por las nuevas en los campos de los agricultores retrasa la transferencia de los
beneficios de la investigaci6n fitotecnica a los agricultores e intensifica el riesgo de
que se presented epifitias, en especial cuando es limitada la diversidad gen6tica de
las variedades cultivadas en la zona. La determinaci6n del period 6ptimo despues
del cual los agricultores deben reemplazar sus variedades y la comprensi6n de los
factors del sistema de producci6n de semilla que pueden impedir la rdpida
sustituci6n de las variedades son esenciales en la transferencia de los beneficios de
la investigaci6n a los agricultores.
En el period despu6s de la Revoluci6n Verde, los aumentos del rendimiento de trigo
que se han logrado mediante el mejoramiento gen6tico han alcanzado cerca del 0.75%
annual, aunque existe cierto grado de variabilidad en la tendencia. A ese ritmo de
aumento, les conviene a los agricultores cambiar las variedades cada cuatro afios,
con base en suposiciones razonables sobre los niveles actuales de muchos de los
pardmetros que influyen en sus opciones. Las diferencias en los micro-ambientes, los
intervalos variables entire los periods en que se dan los aumentos del rendimiento y
las fluctuaciones en las p6rdidas observables causadas por la roya, significant que, en
algunos casos, el period mas convenient para que los agricultores cambien sus
variedades podria ser mas largo.
Desde la Revoluci6n Verde en el trigo, el reemplazo de variedades en Pakistan ha
sido lento en comparaci6n con zonas ecol6gicamente semejantes, como el Punjab de
la India y el noroeste de M6xico. Ademas, en grandes extensions de Pakistan suele
dominar una sola variedad, y hay diversidad s6lo durante el period de transici6n de
una variedad dominant a otra. De 1977 a 1986, en el Punjab la proporci6n de la
superficie de trigo cultivada con variedades que ya no se recomiendan debido a su
susceptibilidad a las royas, fue en promedio de mas del 40%, y de 1982 a 1986, la
superficie sembrada con variedades cuya calificaci6n de infecci6n con roya de la hoja
fue de 50S o mas, constituy6 casi el 60% de la superficie total. Aparte de las perdidas
que una epifitia podria causar, son graves las p6rdidas de rendimiento que la roya
provoca cada afo, y aunque no suelen registrarse extensamente, podrian constituir
una grave p6rdida annual.
Los cuatro studios complementarios que se described en este informed fueron
disefados para analizar los problems del reemplazo de variedades de un cultivo, el
trigo, en un solo pais, Pakistan. Dichos studios examinan los sistemas de reposici6n
de variedades y de producci6n de semilla de trigo, desde que se general lines
nuevas hasta que los agricultores las adoptan. Estas investigaciones se centraron
principalmente en el Punjab, que abarca el 71% de la superficie total cultivada con
trigo en Pakistan, y el 75% de toda la superficie de trigo irrigada en el pais. Existe
una cantidad relativamente mayor de datos sobre esta zona, y su sistema de
producci6n de semilla es el mas desarrollado. No obstante, tanto los m6todos como
los resultados de esta investigaci6n seran sitiles para cientificos fuera de Pakistan
que buscan un marco de referencia para el analisis de los problems
interrelacionados que surgeon de un reemplazo lento de variedades, poca diversidad
de variedades cultivadas y sistemas de producci6n de semilla ineficaces.
En el primer studio se examine el problema del reemplazo lento de variedades
desde el punto de vista del sistema de investigaci6n, y ademas se consideran las
formas de medir el reemplazo de variedades y su diversificaci6n temporal y espacial,
y se aplican al Punjab. Estas mediciones se usan para averiguar si existe un ritmo
6ptimo de reemplazo de variedades y para evaluar el nivel de exposici6n a las
enfermedades. Se presentan tambien otras mediciones que se usan para evaluar el
progress de un program de mejoramiento de trigo, entire ellas, la tasa de
lanzamiento de nuevas variedades y la tasa de aumento del rendimiento a lo largo
del tiempo que puede atribuirse al desarrollo de variedades nuevas. En el Punjab, la
sustituci6n de variedades ha sido much mas lenta de lo que se consider razonable
-cinco o seis anos- y la superficie que se cultiva con variedades susceptibles a la roya
ha sido demasiado extensa (mas del 50% de la superficie de trigo del Punjab en la
primera mitad del decenio de 1980).
El segundo studio evalia los problems de obtener datos basicos sobre la superficie
que se siembra con las distintas variedades. Como la observaci6n de las variedades
que se cultivan compite con muchas otras necesidades de recoleccion de datos,
cualquier estimaci6n en gran escala de la superficie cultivada suele derivarse de
encuestas que se realizaron con otros prop6sitos. La identificaci6n fisica de las
variedades por personal especializado result muy costosa y, por tanto, suele hacerse
con base en lo que dicen los agricultores, quienes no siempre conocen los nombres de
las variedades y a veces las identifican incorrectamente. Los disenos de muestro en
conglomerados tienden a crear grandes errors estandar en las estimaciones de la
superficie sembrada con cada variedad porque la varianza dentro de las unidades
primaries de muestreo (por ejemplo, las aldeas) tiende a ser menor que la varianza a
trav6s de esas unidades.
El tercer studio se centra en la multiplicaci6n y comercializaci6n de semilla por la
Empresa de Semilla de Pakistan (Punjab Seed Corporation, PSC). Se presentan
datos sobre la producci6n actual y anterior de semilla, asi como sobre la present red
de comercializaci6n de semilla en el Punjab. Es evidence que la PSC ha logrado
aumentar la capacidad de producer semilla de trigo en el Punjab. A fines de los 60 y
principios de los 70, antes de que se estableciera la PSC, se vendia cada ano un
promedio de poco mas de 16,000 t de semilla. En los primeros cinco aios despu6s de
su creaci6n, la PSC increments la producci6n de 4,000 a 44,000 t, y ese nivel se ha
mantenido desde entonces. Incluso en la Provincia de la Frontera del Noroeste
(North West Frontier Province, NWFP), donde no existe una industrial especializada
de producci6n de semilla, la capacidad de producer semilla ha aumentado, pues la
Autoridad de Desarrollo Agricola en la NWFP adquiere entire 3,000 y 4,000 t/ano.
Anteriormente, la mayor parte de la semilla provenia del Punjab; en 1986/87, casi
toda procedi6 de la NWFP.
Siguen existiendo problems en la planificaci6n de la producci6n de semilla y la
promocion y comercializaci6n de la misma. Quiza fuera possible acelerar las primeras
etapas de la multiplicaci6n, pero las autoridades no estan seguras cuales variedades
deben multiplicarse. La producci6n no aumenta porque la PSC no puede vender el
excedente de semilla que se produce. El objetivo de la comercializaci6n de semilla
parece ser suministrar semilla pura y certificada al agricultor, no facilitar la
sustitucion rapida de variedades. Las pruebas sugieren que los agricultores utilizan
el sistema formal de semilla mas para cambiar sus variedades que para obtener
semilla nueva de las variedades que ya cultivan. No obstante, se requeriria un
sistema active de producci6n de semilla que tuviera nexos cercanos con la
investigaci6n y la extension para lograr una reposici6n mas rapida de variedades en
el period posterior a la Revoluci6n Verde.
La comisi6n que reciben los distribuidores privados por el manejo de la semilla es
much menor que la que se les paga por vender fertilizante, un insumo que tiene una
demand mayor y mas regular. Por tanto, la semilla es un insumo cuya distribuci6n
a nivel de fincas todavia es efectuada por el sector public. La industrial privada hace
muy poco esfuerzo para promover su product.
Para difundir la semilla nueva mas rapidamente, son necesarios un mayor esfuerzo
promotional, una red de distribuci6n mas extensa y una comisi6n mas elevada para
los distribuidores. Estos cambios probablemente requeriran que se incremente el
precio de la semilla. Aunque un precio mas alto reducird a corto plazo la demanda de
semilla entire los agricultores, el efecto neto podria ser un reemplazo de variedades
mas rapido, siempre que los precious mas altos condujeran a una mayor promoci6n, a
una mejor red de distribucion y, por tanto, a una reducci6n del tiempo necesario para
que las nuevas variedades Ileguen al agricultor. En el Punjab de la India, los precious
del trigo son mayores y hay un reemplazo de variedades mas acelerado que en el
Punjab de Pakistan.
El cuarto studio examine las percepciones de los agricultores. S61o una tercera o
cuarta parte de los agricultores encuestados en los tres principles sistemas de
cultivo opinaron que algunas variedades eran mas resistentes a las enfermedades
que otras, y s6lo una cuarta parte o menos pensaba que las variedades podian perder
La raz6n de que los agricultores conocieran las nuevas variedades fue mas clara en la
zona del Punjab donde se cultiva arroz y trigo, y donde la difusi6n de las nuevas
variedades ha sido extensa. En esta zona, el conocimiento de las nuevas variedades
se ve influido por el nivel de educaci6n, el contact con los servicios de extension y el
hecho de vivir en una aldea donde muchas parcelas se siembran con estas
variedades. Algunas de estas variables, en especial el nivel de educaci6n o
escolaridad y los factors relacionados con la aldea, tambien tienen influencia en
otras zonas encuestadas, como la zona productora de algodon y trigo del Punjab y la
region irrigada de Mardan, NWFP.
Frente a otras variables, el tamano de la finca suele ser una determinante menos
important del conocimiento o adopci6n de variedades en aquellos lugares donde las
nuevas variedades se han extendido mas. El pequeno agricultor adoptara las
variedades nuevas una vez que las conoce, pero los grandes agricultores son los que
suelen enterarse primero, por su mayor nivel de escolaridad y su contact mas
asiduo con la extension y otras fuentes de informaci6n. El tamano de la finca es
important en todas las zonas en el sentido de que los grandes productores tienden a
sembrar tanto variedades viejas como nuevas, sin especializarse en ninguna. Los
pequefos agricultores que adoptan una nueva variedad por lo general cultivan con
ella todas las tierras que dedican al trigo.
La raz6n mas comun que dieron los agricultores en las tres zonas de cambiar
variedades fue el rendimiento. La mayoria de ellos creia que el rendimiento de las
nuevas variedades era superior, pese a que unos cuantos percibieron que este
aumento del rendimiento sobre los rendimientos reducidos de sus antiguas
variedades tenia que ver con la resistencia a las enfermedades y otros factors. En el
andlisis multivariado, por lo general el factor que mas influye en la adopci6n es la
percepci6n de los agricultores de que las nuevas variedades rinden mas, aunque
tambi6n es important su comportamiento cuando se usan fechas de siembra tardias,
sobre todo en la zona algodonera.
En las tres zonas encuestadas en 1985/86, el 50 6 60% de todos los campos de los
agricultores encuestados se sembraron con semilla reservada de la cosecha anterior.
Otro 20 6 30% se cultiv6 con semilla obtenida de agricultores vecinos. Es evidence
que la transferencia de agricultor a agricultor constitute un medio important de
difusi6n. En las tres zonas, entire el 45 y 55% de los agricultores que sembraban
variedades lanzadas despues 1978 habian conseguido inicialmente semilla de otros
agricultores. De los productores que sembraban variedades nuevas, obtuvieron
inicialmente semilla del dep6sito mas del 33% en la zona productora de arroz y trigo,
pero s6lo el 14% de los que viven en Mardan.
En las tres zonas, la escolaridad y el contact con los servicios de extension fueron
las dos variables que mas se relacionaron en forma positive y significativa con el
conocimiento correct de d6nde se localizaba el dep6sito de semilla. Es possible que en
el Punjab la distancia del dep6sito estuviera negativamente relacionada con el
conocimiento de d6nde se encuentra este. En el Punjab, los agricultores que conocian
las variedades nuevas tambien eran los que probablemente sabian d6nde quedaba el
deposito; en Mardan no hubo tal relaci6n, lo cual confirm la falta relative de
importancia del dep6sito de semilla en la difusi6n de las variedades nuevas.
En las tres zonas, s61o el 40 6 50C/% de los agricultores que siembran su propia semilla
utilizan tecnicas como la seleccion de una parcela especial o la trilla por separado de
la semilla y el grano. Hubo muy pocas relaciones significativas entire las
caracteristicas del agricultor y el manejo de la semilla.
El contact con los servicios de extension no fue una causa muy important del
conocimiento y adopci6n de las variedades nuevas. Las demostraciones de las
variedades por los servicios de extension quiza no se han difundido lo suficiente y
ademas no siempre se han adecuado a las distintas circunstancias agrecol6gicas o
factors adversos de los sistemas de cultivo. Por otra parte, no se han coordinado
bien los esfuerzos de promocion de la investigation, la industrial semillera y los
servicios de extension.
En conjunto, los resultados de los cuatro studios realzan la importancia que tiene el
reemplazo regular de variedades para los agricultores y para todo Pakistan. Los
metodos que se usaron en esta investigaci6n -analisis institutional, analysis de los
datos de la investigaci6n y encuestas entire los agricultores- ofrecen un medio de
evaluar las complejas relaciones entire el fitomejoramiento de trigo, la verificaci6n y
el lanzamiento de las variedades, la producci6n y distribuci6n de semillas, la
extension, las political gubernamentales y los cambios de variedades que hacen los
productores. Si bien las conclusions que se presentan en este informed son
especificamente de un cultivo, un lugar y un period determinados, se les puede
considerar tambien como hip6tesis que se podrian aplicar en distintas situaciones,
quiza con alguna modificaci6n.
En el future, en los studios realizados para ampliar el conocimiento de los factors
que afectan el reemplazo de las variedades, se podrian crear metodos para establecer
el numero aproximado de variedades que seran lanzadas por los programs
fitotecnicos mas avanzados de paises con grandes zonas productoras del cultivo en
cuesti6n, y la diversidad genetica que esas variedades deberan poseer. Asimismo,
seria muy litil un mayor numero de studios de los sistemas de semilla que han
logrado cierto nivel de eficacia en comercializar semillas de distintos cultivos. De
hecho, existe ya este tipo de studios; lo que habria que hacer es agregar la
perspective del reemplazo de variedades a la descripci6n legal e institutional que a
menudo contienen. Tambien es necesario realizar mas investigaciones para verificar
empiricamente el efecto relative de los factors que influyen en la demand de
semilla para reemplazar variedades por parte de los agricultores. Por filtimo,
studios de otros paises y en especial, de otros cultivos, mejorarian nuestro
entendimiento de los aspects del reemplazo de variedades que son universales, y de
los cambios en las suposiciones y metodos que son necesarios para analizar factors
mas especificos respect al tiempo, al lugar y a determinados cultivos.
En raison meme de la lenteur avec laquelle s'effectue dans les exploitations agricoles
des contrees productrices de ble la substitution des plus anciennes varieties par de
nouvelles, les agriculteurs ne beneficient qu'avec retard des resultats de la recherche
en phytotechnie et sont, de plus, exposes au risque de voir se presenter des epidemies,
notamment quand la diversity genetique des varietes cultivees dans la region est
limitee. Pour que les agriculteurs puissent effectivement profiter des resultats de la
recherche, il faut avant tout determiner la period optimale pour le replacement
des varieties qu'ils cultivent et bien connaitre les facteurs du system de production
de la semence susceptibles de faire obstacle a une rapide substitution des varieties.
A la suite de la Revolution Verte, les augmentations de rendement en ble obtenues a
la faveur de 1'amelioration g6entique ont ete de pres de 0,75% par an, encore que cette
tendance n'ait pas ete uniform partout. Une telle augmentation suggere qu'il est de
l'interet des agriculteurs de changer de varieties tous les quatre ans, sur la base de
suppositions rainsonnables quant aux niveaux actuels de nombreux parametres qui
influencent leurs decisions. Les differences de microenvironnement, la variability des
intervalles entire les periods de meilleur rendement et les fluctuations des pertes
occasionnees par la rouille font que, dans certain cas, les agriculteurs devront
prolonger la p6riode precedant le changement des varieties.
Depuis la Revolution Verte la substitution de vari6ets de ble au Pakistan s'est operee
plus lentement que dans d'autres zones don't les conditions ecologiques sont
analogues, telles le Punjab indien et le nord-ouest du Mexique. De plus, une seule
variety est g6neralement cultivee au Pakistan sur de grandes etendues et il n'y a de
diversity que dans la period de transition d'une variety dominant a une autre. En ce
qui concern le Punjab, de 1977 a 1986, la culture de varietis de ble qui ne sont
d'ailleurs plus conseilles parce que susceptibles aux diverse rouilles occupait en
moyenne plus de 40% des terres; de 1982 a 1986 la superficie ensemencee en varieties
pour lesquelles le taux d'incidence de la rouille de la feuille etait de 50S ou plus
representait pres de 60% de la totality des terres cultivees. Sans parler des pertes
que peut provoquer toute 6pidemie, les pertes de rendement occasionnees chaque
annee par la rouille sont considerable et, bien que relativement limitees, elles
pourraient donner lieu a de lourdes pertes annuelles.
Les quatre etudes complementaires don't on trouvera ici le compete rendu ont pour
objet l'analyse des problems associes au replacement de varieties dans la culture
du ble dans un seul pays, le Pakistan. Les systems de substitution de varieties et de
production de semence y sont examines, depuis 1'obtention de nouvelles lignees
jusqu'a 1'adoption de ces dernibres par las agriculteurs. Les recherches ont ete
principalement centrees sur le Punjab don't les cultures de ble couvrent 71% de la
superficie total des terres ensemencees en blW au Pakistan et 75% des terres de ble
irriguees du pays. Les informations concernant cette zone sont relativement plus
abondantes et le system de production de semence y est plus developpe. Neanmoins,
les m6thodes et resultats de cette recherche pourront etre utiles aux chercheurs qui,
en dehors du Pakistan meme, ont besoin d'un cadre de reference pour 1'etude de
problems qui peuvent se presenter en liaison avec une lente substitution de
varieties, une faible diversity des varieties cultivees et des systems de production de
La premiere etude est consacree au problem de la substitution tardive de varieties
du point de vue du system de recherche; de plus, les diverse manieres de mesurer
le replacement de varieties et leur diversification dans le temps et dans l'espace,
appliquees au Punjab, y sont exposees. Ces methods de measure servent a
determiner si il existe un rythme optimal pour la substitution de varieties et a
evaluer le degree de vulnerability de ces dernieres aux maladies. D'autres types de
measures sont egalement proposes pour evaluer l'avance d'un programme
d'amelioration du ble, tels le taux de lancement de nouvelles varieties et le taux
d'augmentation du rendement pendant la period requise pour que se d6veloppent de
nouvelles varieties. Au Punjab, la substitution de vari6tes a ete beaucoup plus lente
qu'ont pouvait raisonnablement l'esperer de 5 ou 6 ans et la culture de varieties
sensibles a la rouille s'est etendue sur une tries grande superficie (plus de 50% des
terres a ble du Punjab pendant les premieres annees 80).
La deuxieme etude traite des problems que pose 1'obtention de donnees relatives a
la superficie des terres ensemencees avec diverse varieties. L'observation des
varieties cultivees coincide souvent avec la necessity de recueillir d'autres types de
donnees, de sorte que toute estimation global de la superficie cultivee provient
souvent d'enquetes menees dans une toute autre perspective. L'identification de visu
des varieties cultivees par un personnel specialist etant fort onereuse, il faut se fier
generalement aux dires des agriculteurs, lesquels ne connaissent pas toujours les
noms des varieties et parfois ne les identifient pas correctement. Les
echantillonnages issues d'ensembles de cultures peuvent induire une grande erreur
standard dans l'estimation de la superficie cultivee avec chaque variety, du fait que
la variance dans les unites primaires d'echantillonnage (les villages, par example)
tend a 6tre inferieure a la variance global de ces unites.
La troisieme etude porte sur la multiplication et la commercialization des semences
par la society de production de semence au Pakistan (Punjab Seed Corporation,
PSC). Les chiffres correspondent a la production anterieure et a la production
actuelle sont pr6sente, ainsi que les donnees relatives au reseau de
commercialization des semences au Punjab. De toute evidence la PSC a eleven la
production de semence de ble au Punjab. A la fin des annees 1960 et durant les
premieres annees 1970, avant que soit creee la PSC, les ventes annuelles de
semences depassaient a peine 16 000 tonnes en moyenne. Au course des cinq
premieres annees d'activite, la PSC a porter la production de 4 000 a 44 000 tonnes et
l'a maintenue a ce niveau, y compris dans la Province de la Frontiere du Nord-Ouest
(Northwest Frontier Province, NWFP) ou il n'existe pas d'industrie sp6cialis6e dans
la production de semences, la capacity de production a augmented et l'Autorite de
developpement agricole de la NWFP acquiert 3 000 a 4 000 tonnes par an.
Auparavant, la majeure parties de la semence provenait du Punjab, mais des 1986/87
elle a ete fournie presque en totality par la NWFP.
Des problems important subsistent dans la planification de la production de la
semence, de mime que dans la promotion et la commercialization. Peut-etre serait-il
possible de faciliter les premieres tapes de la multiplication, mais les autorites ne
savent pas exactement quelles sont les varieties qu'il serait bon de multiplier. La
production n'augmente pas parce que la PSC ne peut vendre l'excedent de sa
production. Fournir a l'agriculteur une semence pure et dfiment certifiee semble ktre
le premier objectif en matiere de commercialization et non faciliter la substitution
rapide de varieties. Apparemment les agriculteurs ont plus recours au system
official pour changer de variety que pour obtenir de nouvelles semences de varieties
qu'ils cultivent d6ej. Neanmoins, un system de production de semence travaillant
en etroite liaison avec les centres de recherche et les services de vulgarisation serait
fort utile pour active la substitution de varieties dans la p6riode suivant la
La commission que percoivent les distributeurs priv6s dans le cadre de la
commercialization de semence est tres inferieure a celle qui leur est accordee pour la
vente d'engrais, produit qui fait l'objet d'une demand plus important et plus
reguliere. De ce fait, la distribution de semence au niveau des exploitations agricoles
est effectuee par le secteur public. L'industrie privee, pour sa part, ne fait pas grand
effort pour promouvoir sa production.
La diffusion plus rapide de semence nouvelle requiert une plus grande activity
promotionnelle, un reseau de distribution plus etendu et l'octroi d'une commission
plus levee aux distributeurs. Sans doute ces modifications donneront-elles lieu a
une majoration du prix de la semence laquelle, a court terme, motivera la reduction
de la demand de la part des agriculteurs mais pourra, neanmoins, avoir pour effet
l'acceleration du replacement de vari6tes, si toutefois cette hausse des prix favorite
la promotion et 1'extension du reseau de distribution, d'ou une reduction du temps
necessaire pour que les nouvelles varieties soient mises a la disposition des
agriculteurs. Au Punjab indien les prix du ble sont plus eleves et la substitution de
varieties plus rapide qu'au Punjab pakistanais.
Le point de vue des agriculteurs fait l'objet de la quatrieme etude. Un tiers ou un
quart seulement des agriculteurs aupres desquels ont eu lieu les enquites dans les
trois principaux systemes de culture consideraient que certaines varieties etaient
plus resistantes que d'autres aux maladies, et un quart d'entre eux peut-Otre mme
moins pensait que les varieties pouvaient perdre leur resistance.
Les agriculteurs du Punjab dans la zone de culture de riz et de ble 6taient plus
informs des nouvelles varieties parce que ces dernibres y ont fait l'objet d'une plus
large diffusion. Le niveau d'instruction des agriculteurs dans cette zone, leur contact
avec les agents de vulgarisation et le fait de vivre dans une agglomeration ou ces
varieties sont cultivees dans de nombreux champs, sont autant de facteurs qui ont
favoris6 la connaissance des variet6s par ces agriculteurs. Certaines de ces variables,
le niveau d'instruction ou de scolarit6 notamment, ainsi que certaines condition dans
les villages ou vivent les agriculteurs, exercent egalement une influence dans
d'autres zones ainsi que l'ont revele les enquetes effectuees dans la zone de culture
de coton et de ble du Punjab et la region irriguee de Mardan, NWFP.
Comparee a d'autres variables, la taille de l'exploitation agricole ne semble pas jouer
un role determinant en ce qui concern la connaissance ou l'adoption de nouvelles
varieties dans les zone ou celles-ci se sont repandues. Le petit cultivateur n'adopte de
nouvelles varieties que s'il les connait, mais les grands agriculteurs en sont informs
les premiers et ce pour trois raisons: leur degree d'instruction plus elev6, leurs
contacts plus frequents avec les services de vulgarisation, enfin les autres sources
d'information auxquelles ils ont access. Mais, dans toutes les zones, les dimensions de
l'exploitation agricole sont importantes du fait que les grands producteurs ont
tendance a cultiver aussi bien les varieties anciennes que les nouvelles, sans
distinction, alors que les petits agriculteurs qui adoptent une nouvelle variety la
cultivent sur toutes les terres qu'ils destinent a la production de ble.
Le rendement a ete la raison la plus generalement donnee pour changer de variete
par les agriculteurs des trois zones. La plupart d'entre eux pensait que le rendement
des nouvelles varieties etait superieur aux rendements insuffisants des varieties qu'ils
cultivaient jusqu'alors; mais pour certain cette augmentation du rendement n'etait
pas sans rapport avec la resistance aux maladies et d'autres facteurs. L'analyse de
tous les aspects envisages fait apparaitre que le facteur qui determine le plus
generalement l'adoption d'une nouvelle variety reside dans le fait que les
agriculteurs pensent que les nouvelles varieties ont un meilleur rendement bien que,
dans les zones de culture de coton surtout, leur comportement est important quand
les dates de semis sont tardives.
Dans les trois zones ou ont eu lieu les enquetes en 1985/86, 50 a 60% des champs des
agriculteurs consults etaient ensemences en graines provenant de la recolte
anterieure et reservees a cet usage; 20 a 301 etaient ensemences en graines
obtenues d'agriculteurs voisins. De toute evidence, le transfer de semence entire
voisins constitute un important moyen de diffusion. Dans les trois zones, 45 a 55% des
agriculteurs qui semaient des varieties lancees apres 1978 se les etaient procurees
aupres d'autres agriculteurs. Plus de 33% des agriculteurs de la zone de production
de bl et de riz avaient obtenu les premieres semences du d6pot official, mais cette
proportion n'etait que de 14% parmi les agriculteurs de Mardan.
Dans les trois zones, le degr6 d'instruction des agriculteurs et leurs relations avec les
services de vulgarisation ont ete les deux variables les plus etroitement et
positivement lies au fait que les agriculteurs savaient ou se trouvait le dep8t de
semence. I1 est possible qu'au Punjab l'eloignement du d6ept ait eu une relation
negative avec la connaissance de son emplacement exact. Ceux des agriculteurs du
Punjab qui connaissaient les varieties nouvelles 6taient egalement ceux qui savaient
ou se trouvait le dep6t. I1 n'en est pas de mime a Mardan, ce qui prouve l'importance
relative du dep6t dans la diffusion de varieties nouvelles.
Dans ces trois zones, 40 a 50% seulement des agriculteurs qui utilisent leur propre
semence emploient des techniques telles le choix d'une parcelle speciale ou le bettage
separ6 de la semence et du grain. On n'a observe que tries peu de relations
significatives entire les caracteristiques de l'agriculteur et la facon don't il gere ses
Les contacts 6tablis avec les services de vulgarisation n'ont pas joue un role tres
important dans la connaissance des varieties nouvelles et leur adoption par les
agriculteurs. Les demonstrations don't ont ete l'objet les varieties nouvelles de la part
des services de vulgarisation n'ont peut-etre pas ete assez largement diffusees et
n'ont pas toujours 6te adaptees aux conditions agro-ecologiques des systems de
culture ni n'ont tenu compete de contraints de culture. I1 n'y a pas eu de bonne
coordination entire les efforts de promotion de la recherche, I'industrie de production
de semence et les services de vulgarisation.
Dans l'ensemble, la conclusion a tirer de ces quatre etudes est que le replacement
progressif de variet6s est important non seulement pour les agriculteurs, mais pour
tout le Pakistan. Les methodes appliquees dans cette recherche analyse
institutionnelle, analyse des donn6es de la recherche et enquetes aupres des
agriculteurs offrent le moyen d'evaluer les relations complexes qui existent entire la
recherche visant a ameliorer la quality et le rendement du ble d'une part et, d'autre
part le contr6le et le lancement de varieties, la production et la distribution de
semences, la vulgarisation, les politiques officielles et les changements de varieties
par les agriculteurs. Bien que les conclusions pr6sentees ici se referent
specifiquement a une region, une culture et une period determine, elles peuvent
etre considerees comme autant d'hypothbses valables non sans quelque
modification peut-etre dans d'autres situations.
Dans les etudes effectuees a l'avenir en vue de faire conaitre mieux les facteurs qui
entravent la substitution de varieties, des m6thodes pourraient &tre proposees pour
6tablir le nombre approximatif des varieties issues des programmes d'amelioration
les plus avances de pays producteurs oi les cultures de ble couvrent de grandes
surfaces, ainsi que la diversity g6netique que devraient presenter ces varietes. De
meme, il serait fort utile de mener de plus nombreuses 6tudes sur les systems de
production de semence qui ont prouve une certain efficacite dans la
commercialization de semence de diverse cultures. En fait, ce type d'etudes existe
deja, mais il serait souhaitable qu'elles ne soient pas limitees a la description legale
et institutionnelle qu'elles contiennent le plus souvent et qu'elles soient convues dans
la perspective du replacement de varietes. I1 serait 6galement necessaire de
proceder A des recherches qui auraient pour objet de v6rifier de facon empirique
l'influence des facteurs qui interviennent dans la demand de semence des
agriculteurs d6sireux de remplacer certaines vari6tes. Enfin, des etudes emanant
d'autres pays et portant sur d'autres cultures nous permettraient de mieux connaitre
les aspects universels de cette substitution de vari6tes et les changements A apporter
tant aux suppositions qu'aux methodes n6cessaires pour analyser des facteurs plus
specifiques en ce qui concern le temps, le lieu et des cultures determinees.
Paul W. Heisey
The speed with which new varieties are released and diffused to the farming
population is an important factor influencing the benefits realized from plant
breeding. Diffusion of new varieties ensures continuing increases in productivity
through the increased yield potential of new varieties; it reduces the time lapse from
the investment in research to the time the benefits are realized, thereby increasing
the returns to research; and it helps maintain genetic resistance to diseases and
The last benefit is particularly important in wheat. The resistance of released
varieties often breaks down within a few years because pathogens, especially of leaf
rust (Puccinia recondita) and stripe rust (P. striiformis), are continually evolving. To
guard against loss when varietal resistance breaks down, it is useful to diversify
varieties 1) over time, by rapidly replacing the varieties available to farmers, and
2) at a given point in time, by ensuring the availability of several varieties with
different sources of genetic resistance to the dominant pathogens so that farmers can
plant several varieties and reduce the risk of losses, or change varieties quickly if an
epidemic breaks out. Varietal replacement over time and varietal diversification at a
given point in time are both important targets of any program to develop and diffuse
new wheat varieties.
Pakistan is one country in which varietal replacement has been slow. Though
farmers quickly adopted semidwarf wheats at the time of the Green Revolution,
since then varietal change has lagged compared with similar wheat-growing
environments such as the Indian Punjab and northwestern Mexico. Wheat
researchers have been aware of the problem of slow varietal replacement for some
time. Pathologists, plant breeders, and other scientists have warned that a rust
epidemic similar to the one that occurred in 1977/78 is likely to occur. However, the
exact dimensions of the problem could not be determined; although some information
on area planted to specific varieties is collected in Pakistan, at least for the Punjab,
data are not made available publicly or in a timely fashion.
In the early 1980s, the Pakistan Agricultural Research Council (PARC)/International
Maize and Wheat Improvement Center (CIMMYT) Collaborative Wheat Project, in
cooperation with provincial research institutes, undertook a program of "integrated
research in farmers' fields in areas representing dominant cropping systems in
which wheat is grown in Pakistan" (Byerlee et al. 1986). As part of this program,
agronomic-economic surveys were used to diagnose farmers' wheat production
problems and to set priorities for research (Byerlee et al. 1984, Hussain et al. 1985,
and Akhter et al. 1986a; Figure 1.1 shows the survey areas). The surveys discovered
that large areas of wheat in northern Pakistan were planted to old, rust-susceptible
varieties. According to these researchers, variety is an important factor affecting
farmers' yields and is also among the factors given the highest priority for immediate
These findings emphasized the need to develop methods and conduct research to
understand the problem of limited varietal diversification and replacement more
thoroughly. Additional research was warranted for many reasons. Seed is a basic but
relatively uncomplicated and inexpensive component of wheat production technology.
The contrast between the rapid initial adoption of high yielding varieties and the
present slow rate of varietal replacement, and between rates of varietal replacement
in Pakistan and in other countries, certainly suggested further study. Economic
losses caused by disease in normal years in Pakistan, let alone the losses that could
be incurred in an epidemic, are severe enough to make the subject of varietal
replacement a serious policy issue. Pakistan was therefore a good location for
exploring these issues in greater depth.
The results presented in this report come from four complementary studies designed
to analyze the wheat seed system in Pakistan from the development of new lines by
researchers to adoption by farmers. The report focuses on the Punjab, which contains
71' of Pakistan's total wheat area and 75% of all the irrigated wheat area in
Pakistan, because relatively more data are available and the seed system is most
I I I I I
Figure Survey areas, Pakistan.
Figure 1.1. Survey areas, Pakistan.
The first study, summarized in Chapter 2, analyzes slow varietal replacement from
the perspective of the research system. Measures of varietal replacement and spatial
diversification are presented and used to investigate whether there is an optimal
rate of varietal replacement in the Punjab and to assess the level of disease
exposure. Other measures of assessing the progress of a wheat breeding program are
also discussed, including the rate of release of new varieties and the rate of yield
gain over time attributable to the development of new varieties.
The second study, most of which is presented in Chapter 3, assesses problems in
obtaining the raw data on varietal coverage required for much of the subsequent
analysis in this report. The study is the result of a series of special surveys
conducted by social scientists from PARC. The surveys were designed to monitor
wheat varietal coverage and change in the three cropping systems covered by the
agronomic-economic diagnostic surveys.
Chapter 4 discusses the third study, which concentrates on seed multiplication and
marketing by the Punjab Seed Corporation (PSC). Data are presented on past and
current seed production and the present seed marketing network in the Punjab.
The fourth study, discussed in Chapters 5 and 6, concentrates on farmers. Chapter 5
looks specifically at farmers' seed sources and seed management, describing farmers'
contacts with the formal seed system and the operation of the informal seed system.
Chapter 6 concentrates on farmers' use of seed in the context of the literature on
technology adoption. Farmers' perceptions of wheat technology in general, varieties
in particular, and the wheat disease threat are presented and analyzed. Farmer
characteristics are analyzed statistically for their effects on farmers' awareness and
adoption of new varieties.
The four studies presented in this report look explicitly at the research system, the
formal seed system, the informal seed system, and the varietal monitoring system.
The relationships between these systems and the rate of varietal replacement in
farmers' fields is diagrammed in Figure 1.2. No separate analysis of agricultural
extension is conducted. However, evidence of extension's role in varietal diffusion is
available from the discussion of extension as a source of technological information
and the effect of extension contact on farmers' awareness and adoption of new
The final chapter of this report presents some conclusions and recommendations
aimed at varietal monitoring; wheat breeding, varietal testing, and release; seed
production and distribution; extension; and government policy. Although the studies
described in the pages that follow focus on the Punjab of Pakistan, the results and
recommendations should be useful for all who are concerned with speeding the
benefits of breeding research to its ultimate clients, the farmers.
1 General evaluations of agricultural extension for the Punjab can be found in Khan
et al. (1984) and Haq et al. (1986), and for Mardan in Freedman et al. (1986).
Formal seed system
Quantity of seed
Time to multiply
- varietal replacement 4-
in farmers' fields
Number and diversity
Yield gains to new
Time to test and
Farmer evaluation of
of rust or
Figure 1.2. Analysis of the system.
Farmers' seed system
How farmers multiply
How seed is diffused
within or between villages
Wheat Varietal Diversification
over Time and Space as Factors in Yield
Gains and Rust Resistance in
Derek Byerlee and Paul W. Heisey
Several studies have analyzed the overall returns to wheat breeding research (e.g.,
Nagy 1984 and Zentner and Peterson 1984). However, the concepts of a target or
optimal rate of varietal replacement and of the degree of varietal diversification over
space have received little attention, and appropriate measures to monitor
replacement or diversification in farmers' fields also merit further study. This
chapter addresses those issues, first by introducing some basic concepts and
measures of varietal replacement and diversification, and then by applying them to
recent trends in wheat varietal diffusion in the Punjab of Pakistan.
Optimal Varietal Replacement
Any plant breeding program will have an optimal time span during which new
varieties are released and old ones are replaced. The length of this period depends on
the benefits and costs of releasing new varieties. The benefits in turn depend on
1) the yearly genetic gains in yield or improvement in other desirable characteristics
such as maturity, 2) the rate of varietal decay caused by breakdown in disease
resistance, and 31 the genetic diversity for disease resistance in varieties that are
currently grown. Because these factors, particularly the third one, change from year
to year, the optimum period for varietal replacement will vary over time. The costs of
replacement depend on the costs of breeding new varieties, multiplying seed of those
varieties, providing extension to substitute new varieties for old ones in farmers'
fields, and farmers' seed purchase and learning costs.
All of those factors are quite specific to a given situation. The genetic gains in yield
per year in a plant breeding program vary substantially. Annual yield gains may
average 2% or more in exceptional periods, as in the 1960s and 1970s when the
semidwarf character was widely exploited by wheat breeding programs, but over the
long term, genetic yield gains are unlikely to average more than 1% annually
To make it worthwhile for a farmer to change varieties, some threshold yield
increase-aside from the attractions of improved disease resistance and other
superior characteristics that a new variety might have-is usually needed. The
number of years before farmers should change varieties depends upon several
factors, which are shown in Figure 2.1 and discussed in Heisey and Brennan (1989).
If we make the simplifying assumption that farmers' seed does not deteriorate over
time, we can use the yield threshold criterion in a straightforward manner.
Assuming that the price of seed of a new variety is twice the price of seed of the old
variety, and assuming a minimum marginal return on capital of 100% (CIMMYT
1988), the threshold yield increase would be between 7.5% and 10% for a base wheat
yield of 2 t/ha in farmers' fields.' If the annual rate of genetic gain in yield is 1%, a
varietal replacement period of 8-10 years is implied. If breeding gains are more
rapid, or base yields are higher, prices of seed of improved varieties lower, or if
farmers' seed deteriorates, the desired varietal replacement period is considerably
The period in which farmers should grow one variety before changing to another is
shown for various assumptions in Table 2.1. The seed-to-grain price ratio of 1.5
reflects the current ratio of wheat seed to commercial grain in Pakistan; the ratio of
1.75 is nearer the worldwide average. The base yield of 2 t/ha is near current levels
for irrigated wheat in the Punjab; the higher yield (comparable to farmers' yields in
Rate of deterioration
in farmer's seed
Number of years between
Minimum Number of
acceptable years used in
arginal rate assessing benefits
of return and costs
Figure 2.1. Factors influencing the number of years between varietal
1 The higher figure (10'/ ) considers only benefits in the year of adoption. The lower
figure (7.5'%) assumes that seed of the new variety can be kept for future years with
no decline in yields.
northwestern Mexico) illustrates the effects of a substantially higher base yield. Seed
pricing does not affect varietal replacement so significantly when base yields are
Another factor influencing the benefits of varietal replacement is the rate at which
varieties decay as their disease resistance breaks down. The degree of longevity is
obviously quite specific to a given variety and environment. Nonetheless, a recent
review (Khan 1987) suggests that the life of a wheat variety before leaf rust and/or
stripe rust resistance breaks down averages about five to six years in northern
Pakistan (Table 2.2). In the highly favorable wheat growing environment of
northwestern Mexico, where leaf rust is a major problem, the average longevity of a
variety is only three to four years. Data summarized by Kilpatrick (1975) for many
countries suggest that races of rust pathogens change on average about once every
five years in wheat growing areas of the Third World. Because some cultural
practices that increase yields also promote conditions for rust to occur, wheat
varietal longevity is decreasing over time (Khan 1987).
The longevity of new resistant wheat varieties also decreases if they are grown
alongside susceptible varieties. The buildup of inoculum on susceptible materials is
likely to raise the probability of a change in rust races (PARC 1987). In Queensland,
Australia, wheat breeders noted that varietal longevity with regard to stem rust
increased from about five to 10 years when nearly all farmers grew varieties
resistant to the disease and the level of inoculum was kept low.
Table 2.1. Target varietal replacement to meet farmers' minimum requirements
for yield increases (MRR = 100%)
Base yield 2 t/ha Base yield 5 t/ha
Genetic Seed-to-grain Seed-to-grain
gain in yield price ratio price ratio
(%/yr) 1.50 1.75 1.50 1.75
Number of years
to make replacement profitable
0.5 8 11 4 3
1.0 4 6 2 3
1.5 3 4 2 2
Note: Assumes a minimum marginal rate of return (i.e., farmers' minimum return on
capital) of 100%;; also assumes that the ratio of price of seed of improved variety
to price of seed of old variety (i.e., commercial grain price) is 1.50 or 1.75; a seed
rate of 100 kg/ha; no deterioration in farmers' seed; and inclusion of benefits in
years subsequent to a change.
2 For more discussion of the effects of the various parameters, see Heisey and Brennan
Table 2.2. Duration of resistance
wheat varieties to stripe and le
Punjab, Pakistan, 1984
Year of v
Source: Khan (1987)
a Excludes varieties (mostly recei
releases) in which rust resistan
not yet broken down.
b Longevity of variety in terms of
stripe rust resistance.
e in But frequent varietal replacement also
af rusts, incurs costs, since it requires both a
well-developed breeding program and
an established seed multiplication,
eld life distribution, and extension system.
arietyb Such a system should be able to provide
sufficient seed of new varieties two to
7 three years after their release, although
9 limitations on seed multiplication can
4 often increase this period to four years
11 or more. The rate of diffusion is likely to
6 be a function of improved yield or
4 another superior characteristic of the
12 new varieties, rather than disease
12 resistance. However, in periods when
5 yield gains are attained slowly in
4 breeding programs, varietal
G replacement may have to be undertaken
3 largely to protect against disease rather
: than to exploit new yield gains. In that
6 case, the cost of extension to replace old,
susceptible varieties may be quite high
6.3 if farmers are unaware that the
resistance of their varieties has broken
down until a disease epidemic occurs.
On the other hand, when new varieties
nt clearly give higher yields, they may
ce has spread quite rapidly with little input
lea. from extension, as occurred when
semidwarf wheats were first released
The costs and benefits of varietal replacement in Pakistan suggest that wheat
varieties should turn over every five to six years, which is somewhat longer than the
target of three to five years set in Pakistan after the 1978 rust epidemic (Muhammad
1981). The five- to six-year target period would meet the hypothesized threshold at
which it becomes profitable for farmers to change varieties and maintain rust
resistance. The target period would also be practical, given the limitations in
releasing, extending, and multiplying seed of new varieties.
Even a target period of five to six years poses considerable challenges to plant
breeders. For example, in the Punjab alone there are three varietal zones-irrigated
southern Punjab (leaf rust zone), irrigated northern Punjab (leaf rust and stripe rust
zone), and the barani (rainfed) tract-as well as two distinct planting periods
(normal and late) in the irrigated tracts. To meet a target replacement time of five to
six years in all zones, one new variety should be released each year. Some varieties
are adapted across zones, thereby reducing the number of varieties needed, but this
advantage is countered by the fact that some varieties are not accepted by farmers or
are grown on only a negligible area.
Appropriate Varietal Diversification over Space
Assuming that varietal diversification reflects genetic diversity, varietal
diversification over space is desirable mainly to reduce the risk to farmers and to a
nation should a rust epidemic occur. If a susceptible variety covers only a minor
proportion of the planted area, losses in the year of an epidemic are reduced, and in
the next year the variety can be replaced more quickly and cheaply than if it had
been planted on a wider area. Replacing a susceptible variety grown on half or more
of the planted area usually takes more than one year and requires an accelerated
program to procure and distribute seed. Large-scale seed imports may even be
necessary, as during the rust epidemic in Pakistan in 1978.
To actually reduce the risk of an epidemic, diversification must be practiced at the
field level, perhaps by planting multilines or varietal mixtures in a given field.3
There is some difference of opinion over whether planting adjacent fields with
genetically different material slows the spread of disease, but plant pathologists
generally agree that diversification above the field level will probably not influence
the rate at which a rust epidemic spreads.
To monitor both the impact of a plant breeding program and exposure to rust
epidemics, some measures of varietal replacement and diversification are needed.
Measures used in other studies are reviewed here and some are applied to the
situation in Pakistan. Examples are sometimes calculated using hypothetical data
from Table 2.3.
Table 2.3. Proportion of wheat area sown to given varieties at five-year
intervals (hypothetical data)
Year of Percentage area covered by variety
Variety release 1970 1975 1980 1985
1 1962 50 20 10 10
2 1966 30 50 30 10
3 1968 20 30 50 30
4 1978 0 0 10 50
All 100 100 100 100
3 A multiline is a mixture of phenotypically similar plants that have different genes for
rust resistance. A multiline could be developed by crossing a variety to a series of
varieties with different sources of resistance and then backcrossing to the original
variety to regain phenotype. However, each component of a multiline or varietal
mixture must be tested to ensure it has at least one resistance gene that is different
from those in the other components of the mixture/multiline.
Measures of Varietal Replacement
Many different measures of varietal replacement have been proposed, beginning with
an index developed by Johnson and i;ustafson (1963). Some of the more important
measures are discussed by Brennan (1984) and Brennan and Byerlee (1989). The two
measures used in this study are the proportion of recent varieties and the weighted
average age of varieties; they are analyzed in the sections that follow.
Proportion of recent varieties-This index (Brennan 1984) is quite simple to
construct. If we use a five-year period for varietal replacement, then this index, N,, is
simply the proportion of the area planted to varieties released in the previous five
The following hypothetical example illustrates the method. Assume that a target is
set to grow only varieties released in the previous seven years (1n = 7 (two years for
seed multiplication and five years f( r" varietal longevity). Then the indices of varietal
newness N (Ncalculated from Table 2.3 are as follows:
N = 50 = 50
N = 10 = 10
N = 30 = 30
N = 30 + 20 = 50
That is, except for 1980, about one-third to one-half the area is generally sown to new
Weighted average age of varieties-This index consists of the average age, A,, of
varieties grown by farmers, measured in years from varietal release and weighted by
the proportion of area sown to each variety. Again, using the data from Table 2.3, the
calculation ofA can be made as follows:
A = .10*23 + .10I19 + .30*17 + .50:7 = 12.8
A,, = .10:18 + .30* 4 + .50*12 + .102 = 14.0
A = .20*13 + .50:) + .307 = 9.2
A_,, = .50*8 + .30: + .20*2 = 5.6
This index is easy to construct and does not require a "target" replacement period, n,
to be pre-selected. It will be the main index used here.
It is important to note that this is an aggregate measure. Though it is related to the
optimal replacement period for an individual farmer (see above), it is not the same.
In particular, aggregate weighted average age is affected by the amount of time from
varietal release until a substantial amount of seed first reaches farmers, and by the
fact that the actual year when farmers change varieties may differ from farmer to
Measures of Varietal Diversification
It is possible to construct crude indices of varietal replacement that do not consider
the genetic makeup of disease resistance in released varieties. The simplest measure
is the proportion of area devoted to the most popular variety. Targets may be set Lo
keep this proportion in any given area to, say, 33c or less (Duvick 1984). As more is
known about the specific genes conferring rust resistance, this index can be
considerably refined by grouping varieties that carry the same gene sets for
resistance against known rust races to make the calculations (Priestley and Bayles
Varietal Replacement and Diversification
in the Punjab, 1965-86 and 1978-86
Data for analyzing varietal diversification in the Punjab were provided by the Crop
Reporting Service (CRS), Lahore. Since the 1978 rust epidemic, the CRS has
recorded the area planted to specific varieties in randomly selected farmers' fields in
the Punjab. These data are not without limitations; in particular, the CRS does not
allow for the fact that, on average, 12-15% of farmers cannot reliably identify which
wheat variety they grow (Chapter 3). A tendency to rely on physical identification
has probably led to an overestimation of some varieties, especially Yecora, a sister
line of Pari, from which it is almost physically indistinguishable. Nonetheless, data
at the provincial level reasonably reflect general trends in varietal use. At the zonal
level, estimated area in each variety is also fairly consistent with estimates from
independent surveys conducted by wheat breeders and economists from 1985 to 1988
Rate of varietal release-Upon its release in 1965, Mexipak became the first
commercially successful semidwarf wheat in Pakistan. Around 1970 the rate of
varietal release increased substantially with the rapid development of other
semidwarf materials. Two decades later, some 27 new varieties, all but one of them
semidwarf, had been approved for cultivation in the Punjab (Tables 2.4 and 2.5).
Nonetheless, the rate of release in Pakistan is low relative to other countries. In the
Punjab and for Pakistan as a whole, 0.29 varieties have been released per year per
million hectares of wheat cultivated. This figure can be compared to an average of
0.72 varieties/yr/million ha for 15 developing countries and 0.45 varieties/yr/million
ha for 7 developed countries (Table 2.6). The lower rate of varietal release in the
Punjab partly reflects its relative agroclimatic uniformity and large wheat area.
In addition to a relatively slow rate of varietal release, the rate of acceptance of
varieties in the Punjab may be a problem. Of 20 varieties released from 1965 to 1981,
six can be considered failures as they were never planted to more than 1' of the
area, and only nine were adopted on 5Ic or more of the area (Table 2.7). The latter
figure is consistent with adoption in other countries, where only about half of the
varieties released are expected to become commercial successes. Nonetheless, the
number and quality of varieties released in the Punjab would probably have been
sufficient to allow reasonable varietal diversification over space and time, if each
variety had been rapidly adopted by farmers on roughly equivalent areas.
Table 2.4. Varieties released since 1965 and year banned for rust susceptibility,
Rainfed and irrigated areas
Also for rainfed areas
Table 2.5. Release of wheat varieties in the Punjab, 1955-84
Varieties recommended for:
Total number of
Period varieties released
Note: Some varieties are recommended for both normal and late planting or for both
irrigated and rainfed wheat.
Varietal replacement, 1978-86-Varietal adoption and disadoption curves for the
Punjab are given in Figures 2.2 and 2.3 and the years needed for each variety to
reach peak adoption are reported in Table 2.7. Clearly the rate of varietal
replacement in Pakistan has been relatively slow (compare replacement in Mexico,
Figure 2.4). The average number of years from the release of a variety to peak
adoption is nearly eight (Table 2.7). Only one major varietal change has occurred
since Mexipak was introduced 20 years ago. Chenab-70, released in 1970, was
successful but only partially replaced Mexipak. The severe rust epidemic of 1978
Table 2.6. Rate of varietal release in Pakistan and other countries
Number of varieties released per year
per million ha wheat
Pakistan, 1965-85 0.29
Punjab, Pakistan, 1965-85 0.29
15 developing countries, 1967-75 0.72
7 developed countries, 1967-75 0.45
Source: Calculated from Kilpatrick (1975) and other sources.
Table 2.7. Extent and rate of diffusion of wheat varieties released in the
Peak area Years from
Variety Peak year (%) release to peak
Mexipak 1971b 58.0 6
Chenab-70 1978b na (>10.0) 8
Blue Silver* 1987c 13.9 16
Sandal 1982 5.0 9
Lyallpur-73 1985 11.3 12
Yecora** 1980 55.6 6
SA-75 1979 2.6 4
Nuri 1979 1.4 4
LU-26 1984 1.6 8
WL-711 1986' 18.4 8
Bahawalpur-79 1985 2.0 6
Punjab-81 1986c 14.0 5
Pak-81 1991d >50.0O 10
a Excludes varieties that never covered more than 1% of the area (Pothawar,
SA-42, HD-2009, Pavon, Punjab-76, Indus-79).
b Based on alternative reports.
c Projection based on surveys by Akhter et al. (1987).
d Extrapolation based on data to 1987.
* Includes Sonalika.
** Includes Pari-73.
1978 79 80
83 84 85 86 87
Figure 2.2. Percentage of wheat area sown to major varieties, Punjab,
10 .@-ooo.o.e o.._
o o eo oLyallpur-73
lo Malik WO -1Pavon
1978 79 80 81 82 83 84 85 86 87
Figure 2.3. Percentage of wheat area sown to other varieties, Punjab,
caused both Mexipak and Chenab-70 to be replaced by Yecora (seed of Yecora was
imported on a large scale, and it became the dominant variety) and by WL-711
(which came to dominate the southern Punjab). Although both Yecora and WL-711
were removed from the list of recommended varieties in 1982, up to 1985 they were
widely grown. Newer releases, especially Pak-81 and Punjab-81, are replacing them.
The area under Punjab-81 has probably peaked because of that variety's stripe rust
susceptibility and tendency to shatter at harvest, and it is estimated that the area
under Pak-81 will peak at over 50% in 1991. Adoption of Pak-81 is growing quite
rapidly in some areas (e.g., the rice-wheat area of northeastern Punjab) and more
slowly in others.
Three other varieties have been and continue to be important, covering 10% or more
of the area, but usually for specific situations. Blue Silver, also known as Sonalika, is
grown widely and recommended especially for late planting. Lyallpur-73 is
prominent in the rainfed areas. The area planted to older, taller, and desi (local)
varieties has continuously declined and their cultivation is now largely confined to
the driest rainfed areas.
Two measures of varietal replacement (the percentage area sown to new varieties
released in the past five years, N,, and the average age of varieties, A,) were
calculated for 1978-86 using the indices of varietal replacement described earlier.
sown to variety
60- Nacozari-76 *
50- \ I .
40 I ea
I Genaro-81 Altar-84
30 \ 6 Seri-83 **
20- / : N
S/ / .\ /Opata-85
1978 1980 1982 1984 1986 1988
Figure 2.4. Wheat varietal replacement in the Yaqui Valley, Mexico,
When varietal replacement is calculated using the conventional definition of new
varieties (those released in the previous five years: n = 5), the area planted to new
varieties has averaged only 11%. Even if the definition is relaxed to include varieties
released in the past seven years (n = 7), the area sown to new varieties is relatively
The average age of varieties was calculated as about 10 years for all varieties and
about nine for semidwarfs only (Figure 2.5). The average age of all varieties has not
changed even though newer semidwarfs have replaced some of the old tall varieties.
Over 95c of the irrigated area is now sown to semidwarfs and the average age of
semidwarf varieties has actually tended to increase over time (Figure 2.5). This trend
is disturbing because disease pressure is greatest in irrigated areas.
These statistics on varietal replacement in the Punjab compare unfavorably with
data from similar wheat growing areas. For example, in the Indian Punjab, the
percentage of area sown to varieties released in the previous five years averages 30%
compared to 11%7 in the Punjab of Pakistan. Correspondingly the average age of new
varieties in the Indian Punjab (6.5 years) is less than three-quarters of the average
age of new varieties in the Punjab of Pakistan. In the smaller, more uniform wheat
growing environment of northwestern Mexico, the rate of varietal replacement is
much faster than in either India or Pakistan (Table 2.8).
Weighted average age (yr) Percentage area sown
10 to new varieties
in previous five years
8 \ only -20
7 / 10
6 area sown to new 0
1978 79 80 81 82 83 84 85 86 87
Figure 2.5. Weighted average age of varieties and percentage area
sown to new varieties, Punjab, Pakistan, 1978-87.
Exposure to risk of disease-The slow rate of varietal replacement has left much
wheat area in the Punjab exposed to severe risk of a rust epidemic for most of the
past decade. From 1977 to 1986 the area sown to varieties that are no longer
approved because of disease susceptibility averaged 42%. This figure underestimates
the risk of a rust epidemic, since several recommended varieties are also susceptible
to the disease. It also does not include the related problem of growing approved
varieties outside of their recommended zones. The Cereal Disease Research Institute
(CDRI) inoculates plots in farmers' fields to measure the susceptibility of commercial
varieties to leaf rust (PARC 1987). These data suggest that the percentage area
planted to varieties rated at 50S or above (50% severity with a susceptible field
response, based on the modified Cobb scale) averaged 59% between 1982 and 1986
(Table 2.9). Another measure of exposure to an epidemic is the average coefficient of
infection (ACI) for leaf rust over the total provincial wheat area, based on varieties
(weighted by area) sown in farmers' fields. In 1984/85, a relatively high value of 36
was registered for this indicator.'
Aside from the devastating losses that a rust epidemic could cause, actual losses to
leaf rust are already substantial. Scientists estimated a 10% loss (equivalent to
400,000 t of wheat) in 1986/87 in fields planted to such susceptible varieties as WL-
711, Blue Silver, and Yecora; this occurred mostly in the Punjab. Losses of such
magnitude not only justify increased investment in wheat research but also in seed
multiplication, seed promotion, and extension.
Diversification in space-A simple measure of diversification over space is the
percentage area sown to one variety at a given time. This measure can be calculated
at various levels of aggregation-the farm level, district or divisional level, or
Table 2.8. Indices of wheat varietal replacement in the Punjab of Pakistan, the
Punjab of India, and northwestern Mexico, 1977-86
Weighted average Area planted
age of varieties to new varieties
Location (years) (%)
All area 11.0 11
Area under semidwarf varieties 8.8 11
Punjab, India 6.5 30
Yaqui Valley, Mexico 4.1 85
a Varieties released in the past five years.
4 For information on how ACI is calculated, see Stubbs et al. (1986).
provincial level. At the provincial level, one variety usually tends to dominate half or
more of the total wheat area. For example, Mexipak is estimated to have covered
nearly 60% of the area in 1971 (Nagy 1984).
The dependence on one variety is even more striking at the divisional level. Surveys
in the rice-wheat zone showed that Yecora covered 60% of the area in 1984 (Byerlee
et al. 1984). The CRS, Punjab, records an even higher percentage planted to Yecora
in 1982 and 1983 in that zone. In individual villages there is also evidence that
farmers concentrate on one variety (Heisey et al. 1987). At the farm level, where
varietal diversification is a function of farm size, even large-scale farmers with more
than 10 ha plant an average of 75'% of their wheat land to one variety (Table 2.10).
Yield Gains in the Punjab, 1965-86
Since varietal replacement appears to be slow in the Punjab, it is important to
investigate one of the most critical factors in farmers' uptake of new varieties, gains
Methods-A number of methods are available for measuring yield gains due to new
varieties (for a review see Godden 1987). Ideally, recording yield gains due to
breeding will require a varietal trial in which important varieties released over the
period of interest are grown under practices of representative farmers (e.g., date of
planting, fertilizer rate, etc.). In practice, such data are rarely available, and other
less satisfactory approaches must be used.
Two methods of analysis were employed to analyze information from varietal yield
testing trials conducted over years, although only the second method, the vintage
regression model, is reported here. Varieties included in these trials varied from
year to year. In the first method an index is constructed by comparing the yield of
each variety relative to the check variety (see Schmidt 1984 and Orazem and
Table 2.9. Measures of exposure of the wheat crop to a rust epidemic in the
Punjab in recent years
Average percentage area sown to banned varieties, 1978-87" 42
Percentage area sown to varieties wil h leaf rust rating
of 50S or higher in a given year, 1982-87b' 59
Weighted average coefficient of infection for leaf rust of
varieties grown by farmers in 1984/85" 36
a Banned varieties are those removed from the recommended list of varieties by the
Varietal Evaluation Committee.
b Based on recordings of the Cereal Disease Research Institute and data reported in
Pakistan Agricultural Research Council (1987).
c Based on data provided by Cereal Disease Research Institute, Islamabad, and on
area sown to each variety.
Table 2.10. Percentage of total wheat Jameson 1981). The second method
area sown to a major variety at the employs multiple regression analysis to
farm level, 1985/86 estimate a vintage model following
Godden and Brennan (1987). They used
Farm size Rice zone Cotton zone the following general model:
<5ha 89 93
5-10 ha 82 88 Y, = a + I b,D, + crD, + u
> 10 ha 76 82 t j
Source: Survey described in Chapter 5. where Yd is yield of variety i in year t (as
above), D, are a set of dummy variables
(0,1) for the experimental year t and D
are a set of'(0,1) dummy variables for the "vintage" or period of release of a variety.
Godden and Brennan divided D into five-year periods. The Godden/Brennan
formulation allows for nonlinear yield increases over time in newly released varieties.
In our case we were only interested in the long term average rate of increase in yield
gains, and the specification of the vintage function was simplified to the following two
=a + bD, + cV + u, (1)
ln(Y,)= a + VbrDP + cV, + (2)
where ln(Yit) is the natural log of Y,, and V is the year in which variety i was released.
The linear specification (equation 1) provides an estimate of the yield increase due to
new varieties in absolute terms (i.e., c measures kg/ha/year yield gains) while the
logarithmic specification gives the relative yield increase (i.e., c measures %/yr yield
gains). Both specifications were tried, but because the logarithmic specification
generally gave as good or better fit and since we were more interested in the relative
yield gains, we report here only the logarithmic specification.
Data sources-For this analysis, we employed two quite comprehensive data sets.
The first is the results of the International Spring Wheat Yield Nursery (ISWYN)
sent by CIMMYT to many countries for the past 22 years to measure yield
performance and other varietal characteristics such as disease resistance over a wide
range of environments. This nursery has been grown at Faisalabad since 1964/65 and
data are published in the ISWYN reports for all years except 1976. Methods and
practices used in the ISWYN have varied over the years, but the nursery trials have
always used relatively high management levels on small plots, although no fungicide
is applied. The date of planting varies from 10 to 24 November, generally considered
the optimal planting period for this area. The variety Siete Cerros (or its sister lines
Mexipak and Kalyonsona) was included as a check in all ISWYN trials. Over the
years, all widely grown commercial varieties from Pakistan, both tall and semidwarf,
have also been included in the ISWYN, either as advanced lines or as released
The second data set consists of the results of a variety by date of planting trial
conducted annually at the Khanewal Seed Farm since 1979/80. This replicated trial
uses relatively large plot sizes and has included all major commercial varieties
released since 1970. Sonalika is a common check variety over all years. Furthermore,
each variety is grown at four dates of planting, typically ranging from 1 November to
31 December or early January. The performance of varieties over planting dates
enables yield gains to be estimated under conditions more representative of farmers'
conditions, since late planting has become increasingly more common in the Punjab
as cropping intensity has increased. Nonetheless, the trials are planted with higher
levels of inputs, especially fertilizer, than farmers use, so yields are considerably
above farmers' levels.
Results-Results of some of the vintage regression models are reported in Tables
2.11 and 2.12. The F-ratio for the group of dummy variables for year of experiment is
generally highly significant and the coefficient for V, the year of varietal release, is
also significant and positive in most cases.
Estimates of the rate of yield gain due to new varieties are summarized in Tables
2.13 and 2.14 for various subsets of years, varieties, and dates of planting. The
ISWYN data allow the estimation of yield gains to include the effect of the release of
the first semidwarf varieties in the 1960s. However, it is also interesting to know the
yield gains achieved in successive generations of semidwarf varieties. The results of
Table 2.11. Regression results for vintage model for ISWYN data, Faisalabad,
All varieties released since 1965
since 1957,b Excluding
all years All years rust years
1965-86b 1965-86 1973,76,78
Year variety 0.0187 0.0125 0.0102
released (6.07) (3.72) (2.73)
Dummy variables for
year D66-D86c F=8.63" F=8.54' F=3.06'
Constant 7.068 7.564 7.715
n 78 61 50
R2 0.81 0.83 0.68
a Dependent variable is the natural log of yield.
b Includes tall variety C273 released in 1957.
c The number given is the F-ratio to enter the set of dummy variables for year.
both the vintage model and the yield relative to the check (Siete Cerros) indicate that
yield gains for all varieties, including the change to semidwarf from tall varieties,
has been nearly 2% per year, but for the semidwarfs alone, the yield gains have
averaged about 1% per year.
The ISWYN data set includes several varieties, especially Siete Cerros, which have
become susceptible to rust over time. Hence, the estimated yield increase to new
varieties includes both the effect of increasing yield potential of new varieties as well
as the decline in yield of some older varieties caused by a breakdown in rust
resistance. In fact the yield of Mexipak does show fairly high variability compared to
other varieties, probably because of rust attack. An attempt was made to account for
this effect by removing the years 1973, 1976, and 1978, when rust was severe and
Mexipak (Siete Cerros) was given a leaf rust rating of 60S or higher." The estimated
rate of yield increase for "non-rust" years falls from 1.25% to 1.0% using the vintage
model, suggesting an average rate of decay of 0.25% per year caused by a
deterioration in rust resistance. This estimate is only a rough guide and is probably
Table 2.12. Regression results for vintage model for normal season wheat
varieties, Khanewal Seed farm variety x planting date trial, 1980-86
All dates Optimum Late
20 Nov, 10 Dec, date planting
1 Jan 20 Nov 10 Dec, 1 Jan
Year of release .0094 .0083 .0099
(2.52) (1.89) (2.03)
Days planted after 1 Nov -.0128 -.0144
Dummy variables for
year D81-D86 b F=2.35 F=4.08 F=1.86
Constant 8.03 7.80 8.10
n 123 41 82
R2 0.79 0.56 0.70
Note: *,, ** *** significant at the 10%, 5%, and 1% levels, respectively; t-values in
a Dependent variable is the natural log of yield.
b Number given in the F-ratio to enter the set of dummy variables for year.
5 The ISWYN data include rust scores for each variety and often provide an overall
disease rating for the nursery of slight, moderate, or severe rust response.
an underestimate since natural rust infestations in small yield plots, surrounded by
resistant varieties, might be expected to be lower than in large fields of the same
The Khanewal Seed Farm data include 284 observations of variety by planting date
by year. Only popular commercial varieties were included in the experiment but they
can be divided into varieties for normal planting, varieties for late planting, and
varieties for rainfed areas. Table 2.14 summarizes estimated yield gains for various
groups of varieties and dates of planting. In the irrigated Punjab most wheat is
planted between 15 November and 15 December, so the best estimate of yield gains
under farmers' conditions is the average of D2 and D3 or the average of D2, D3, and
D4 (D2 = 20 November, D3 = 10 December, D4 = end of December or early January).
To account for these effects, date of planting was also included as an independent
variable in the vintage equation.
Table 2.13. Estimates of annual wheat yield gains (%/yr) due to varietal im-
provement, ISWYN, Faisalabad, 1965-86
Vintage model Relative to check
Varieties released since 1965
All years 1.25*** 0.75
Excluding rust yearst 1.02** na
since 1957 (all years) 1.87** 1.90*:
a Mexipak or Siete Cerros.
b 1973, 1976, 1978.
** Significant at 1%; **significant at 5(7.
Table 2.14. Estimates of annual wheat yield gains (%/yr) due to varietal
improvement, Khanewal Seed Farm, Pakistan, 1980-86
Normal varieties Early maturing varieties
Over three planting dates .94** -.57*
Optimum planting .83** -.14
Late planting .99** -.78**
Relative to check
Over three planting dates .88** na
a 20 Nov., 10 Dec., 3 Jan..
b 20 Nov.
c 10 Dec., 3 Jan.
d Blue Silver.
* Significant at 5%.
The estimates for normal season varieties again suggest yield gains from 0.75-1.25%
per year. However, for early maturing varieties for late planting and varieties for
rainfed areas, there is no evidence of any yield gains. The evaluation of rainfed
varieties should be conducted in rainfed conditions so the latter result is not
surprising. For late planting, significant yield gains have been made for "normal"
season varieties. These gains largely reflect the relatively good performance of
Pak-81 and WL-711 under late planting (Byerlee, Akhter, and Hobbs 1987). The
overall yield gains estimated relative to the check, Sonalika, also give a similar
estimate of 0.88%, per year.
In synthesis, the results of the analysis of two comprehensive data sets by two
methods give quite comparable results of yield gains to new varieties of about 1% per
year or a little less since semidwarfs were first released, and nearly 2% per year if
the introduction of semidwarfs is also included. These figures are quite comparable
to estimates for Mexico by Evans (1981) and Waddington et al.(1986) and for the UK
and Australia by Godden and Brennan (1987).
There remains the question of whether these results can be applied to yield gains in
farmers' fields under farmers' management. For some varieties, especially Pak-81,
farmer surveys and on-farm experiments show that yield gains under farmers'
conditions are comparable (Byerlee et al. 1986), and we are willing to extrapolate
these results to the farm level. However, to allow for the effect of a breakdown in
rust resistance, a conservative overall estimate of yield gains of 0.75% per year due
to new varieties may be more appropriate.
Implications for Varietal Replacement
This estimate of yield gains can be fed into the model of varietal replacement at the
farmer level described above and by Heisey and Brennan (1989). Given the present
seed-to-grain price ratio of about 1.5, and assuming yield gains of 0.75% per year and
annual deterioration in the performance of varieties of 0.25%, farmers would be
willing to change varieties every four years. If annual yield gains from breeding were
1% and annual deterioration were 0.5%, individual varietal replacement time would
be three years. These desired replacement times, coupled with an aggregate mean
age of varieties of about nine years, imply that seed of new varieties reaches farmers
an average of about seven years after release. Even if the price of seed were raised to
a 2:1 ratio with grain, under the other assumptions specified above, the desired
replacement times would be eight and five years. To maintain an aggregate mean
age of nine years would require that seed reach farmers in four-and-a-half to six
years. Aggregate mean age of varieties would be reduced if the increase in seed price
stimulated seed production and sales.
Several measures of varietal diversity applied to wheat in the Punjab indicate that
varietal replacement has been slow and that exposure to disease risk has been high.
Because of the large area sown to susceptible varieties, losses to rust have been
considerable. However, wheat breeding has continued to provide potential benefits
by increasing yield potential and changing the sources of disease resistance in
available varieties. Although the rate of varietal release per million hectares of
wheat has been somewhat low, the number and quality of the varieties released in
the Punjab have been great enough to allow acceptable varietal diversification over
space and time, had they been more rapidly adopted by farmers. Reasons for the slow
rate of adoption will be among the major topics of following chapters.
i''t.'"' _r_ _
[ Identifying Wheat Varieties
Grown in Pakistan
Paul W. Heisey, M. Ramzan Akhter, Khaleel A. Tetlay,
Zulfiqar Ahmed, Munir Ahmad, Abdus Sattar,
Aslam Khan Khattak, and Muhammad Sharif
This chapter discusses the difficulties of monitoring the varieties grown in farmers'
fields, focusing on the major problems of identification and sampling. It compares
several current estimates of varietal coverage, both to illustrate the problems
involved in estimating the proportion of total wheat area planted to different
varieties and also to expand the analysis of varietal diffusion.'
Current Varietal Monitoring
Wheat varieties planted by farmers in Pakistan are not regularly monitored or
reported. Agricultural statistics published by the Ministry of Agriculture
differentiate between high yielding and other wheat varieties, but those data do not
permit inferences about the rate of varietal replacement or the degree of disease
The most thorough varietal monitoring is presently conducted for the Punjab by the
Crop Reporting Service (CRS) in Lahore, who collect information on wheat varieties
as part of their annual estimation of area and yield. Their estimates of varietal
coverage are not published, however, and wheat scientists are either unaware of
their existence or uncertain of the methodology used to produce them. Although the
CRS hesitates to claim accuracy for its estimates below the provincial level (reasons
for this will become apparent later), their data remain the single most useful source
for any analysis of varietal change in Pakistan, especially since equivalent data for
other provinces are not available.
Wheat varieties grown by farmers are also monitored occasionally by specialized
institutions, such as agricultural extension or the Federal Seed Certification
Department (FSCD). In addition to being occasional, these surveys tend to
overrepresent large-scale farmers and thus to overestimate the area planted to new
In 1985/86 social scientists from the Pakistan Agricultural Research Council (PARC)
conducted a major study of the constraints to rapid diffusion of new, disease-
resistant wheats in three major cropping systems.2 Ferozewala, Gujranwala, and
1 More detailed information on the research reported in this chapter can be found in
Akhter et al. (1986b); Akhter et al. (1987); Sharif et al. (1988); Khushk et al. (1987);
Heisey et al. (1986 and 1987); and Ahmad et al. (1988). Heisey et al. (1986 and 1987)
also describe the methodology used in estimating the relative areas covered by
different wheat varieties.
2 Much of the analysis in Chapters 5 and 6 is based on this study.
Daska tehsils subdistrictss) were selected to represent the rice-wheat system of the
northeastern Punjab; Lodhran, Mailsi, and Bahawalpur tehsils to represent the
cotton-wheat system of the southern Punjab; and the irrigated part of Mardan
District to represent the irrigated Peshawar plain, North West Frontier Province
(NWFP)." (Survey areas are shown in Figure 1.1, page 2.) Thirty villages were
randomly selected in each of the rice-wheat and cotton-wheat survey areas, and 20
villages were randomly chosen in irrigated Mardan. Over 1,200 farmers in the 80
villages were interviewed about the wheat varieties they were growing. Social
scientists returned to the same villages later with wheat breeders from provincial
wheat research institutes to identify the varieties grown in over 3,000 village wheat
fields. In subsequent years, the social scientists have returned to the same villages
to conduct similar surveys of farmers, though there have been no more breeders'
surveys. In addition, farmer and breeders' surveys were conducted in two cotton-
wheat talukas subdistrictss) and two sugarcane-wheat talukas in Sind in 1986/87.
These surveys provide the basis of some of the estimates reported below.
Problems in Varietal Monitoring
The first problem in monitoring varieties is to identify them correctly. Identification
can be done through physical identification or farmer interviews. Large surveys
relying on physical identification are too costly for widespread use because only a few
individuals have the specialized skills to identify with accuracy all varieties grown
by farmers, even when the crop has reached maturity. On the other hand, relying on
farmer interviews can also be problematic. Interviews with farmers in the Punjab
and Sind revealed that 5-20% of the surveyed area was planted to wheat varieties
that farmers could not name. In Mardan, the proportion was much higher: in three
years of surveys, one-third to one-half of the wheat area was planted to varieties that
farmers either could not name or referred to as "Mexipak," which in addition to being
a true varietal name is also the local name for any semidwarf wheat. Another
complicating factor is that farmers identify their wheat varieties by the name given
by the person who initially supplied the seed or on the basis of their own knowledge
of a variety's characteristics. The present system of assigning varieties similar
names makes it easy to confuse varieties (Punjab-81 and Punjab-85, for example, or
Pak-81 and Punjab-81).
3 The major rotation in Mardan is maize-wheat. However, sugarcane-wheat is also
important. The number of crops grown makes it somewhat more difficult to describe
the farming systems of Mardan than the systems in the two other survey areas (see
Hussain et al. 1985).
4 Nonspecialists are likely to rely on gross attributes of plant character such as height,
which results in problems like the overidentification of the particularly short variety
Yecora in relation to its sister lines Pari-73 and Sandal (Chapter 2). Specialists
working in seed certification might be best suited for physical identification of
varieties (N.I. Hashmi, personal communication).
Despite some drawbacks, farmer interviews are likely to remain the major
instrument in varietal monitoring. Even at present, interviews produce useful
information; judicious questioning about the length of time a variety has been
planted can lead to a decision about whether or not it is a recent release, even though
the specific name of the variety is not obtained.
In the surveys reported here, "don't know" responses were divided into "new, don't
know" and "old, don't know" categories. Varieties were labeled "new, don't know" if
the farmer did not know the variety's name but said it was new. Supplementary
questioning about the length of time the farmer had been growing the variety and
the length of time other farmers in the same village had been growing it were used to
confirm the farmer's opinion. This process required a certain amount of subjective
judgment on the part of the enumerator and probably resulted in slight
overestimation of the "new, don't know" category at the expense of the "old, don't
The other major constraint to estimating varietal coverage accurately is sampling.
Most large-scale varietal surveys, such as that of the CRS in the Punjab, are
byproducts of other research efforts and not designed primarily to record varietal
information. Thus, sampling design is unlikely to maximize the efficiency of
estimates of area planted to given varieties. This problem is complicated by the fact
that, to the authors' knowledge, all the surveys described earlier used a cluster
sampling design. Cluster sampling reduces survey costs through the selection of
first-stage sampling units defined by location ("clusters"); second-stage sampling
units are chosen from within the cluster. In the special studies in the rice-wheat,
cotton-wheat, and Mardan areas, the first-stage unit was the village.
Cluster sampling can produce efficient estimators if individual clusters are relatively
heterogeneous with respect to the parameters in question and if there is relatively
high homogeneity between clusters. Unfortunately this is not likely to be the case
with respect to wheat variety. Researchers' experience in conducting specialized
varietal identification studies has shown that varieties tend to be concentrated in
particular villages. A farmer is more likely to grow the same variety grown by
another randomly selected farmer in the same village than a variety grown by a
randomly selected farmer in a different village. Similarly, two wheat fields inspected
by a breeder in the same village are more likely to be planted to the same variety
than a random pair of wheat fields from two different villages. Estimates of varietal
coverage from cluster sampling designs are therefore likely to have relatively high
sampling error. In the short run, this method can be improved by choosing a
relatively high number of clusters (villages) and a relatively low number of farmers
(or fields) within each village.:
5 In the long run, as the CRS moves towards area frame sampling designs, better
estimates of varietal coverage are likely to result as a by-product.
Finally, if a survey is to provide estimates of varieties that cover relatively little
area, it is in effect sampling from a rare population. Unless a relatively expensive
survey is designed, it is unlikely that the estimates will be very accurate.
Survey of Farmers and Breeders' Survey, 1985/86
The special surveys conducted in 1985/86 exemplify some of the difficulties in
accurately estimating varietal coverage. Varieties were identified by farmers and by
wheat breeders in the same villages. Because of the sampling problem and the
Table 3.1. Estimates of percentage area
planted to major wheat varieties in
three zones of Pakistan. survey of
farmers and breed
a Estimate from br
outside the 95% c
estimate from far
identification problem discussed
earlier, there were large discrepancies
in some of the estimates (Table 3.1).
ers' survey, 1985/86 These discrepancies can be evaluated
by survey area as well as by variety.
Farmer Breeders' It is clear that a major reason for the
survey survey differences in estimates in Mardan is
farmers' more limited knowledge of
26 16 varietal names. Although very little
17 13 Mexipak is grown now in any area of
10 41 Pakistan, farmers in Mardan said
6 165 they were growing "Mexipak" on one-
2 13" quarter of the surveyed area.
Breeders also identified a good deal
more WL-711 than farmers did; on
37 46 the other hand, estimates for the new
12 10 variety Pak-81, which is spreading
rapidly in Mardan, and the old variety
SA-42, which has a distinctive
26 <1~ appearance at maturity and a
20 24 distinctive local name, were relatively
10 34a close in the two surveys. Nonetheless,
it is likely that percentages from
feeders' survey lies farmer surveys in areas like Mardan
confidence interval of underestimate the coverage of major
mer survey, varieties."
The discrepancies for Yecora and Sandal in the rice-wheat zone might be related to
the fact that they are sister lines. Yecora was introduced in 1974 and large amounts
of seed were imported; in 1981 it was banned. Yecora's sister lines Pari-73 and
Sandal were released in Pakistan in 1973 and are still approved but recommended
for replacement. Although it is clear that Yecora was the dominant variety in the
6 For example, in the next two years (1986/87 and 1987/88), area under "new, don't
know" varieties, as well as Pak-81, increased substantially in Mardan. Most of this
"new, don't know" area can be presumed to be under Pak-81.
Punjab in the late 1970s and early 1980s, there has probably been some tendency for
farmers and the CRS to overestimate Yecora and underestimate Pari-73 and Sandal.
In all three areas, estimates for WL-711 were higher in the breeders' survey and
lower in the survey of farmers. For Blue Silver the situation was exactly the reverse.
In the 1985/86 surveys, the discrepancy for Blue Silver was particularly apparent in
the cotton-wheat zone. WL-711 is a variety of intermediate maturity and Blue Silver
is early maturing. Though their physical characteristics are somewhat similar, they
can be distinguished near maturity with only moderate difficulty.
The discrepancy between farmers' and breeders' identification of WL-711 in Mardan
is partially accounted for by farmers' tendency to be unaware of varietal names.7 The
discrepancy for the cotton zone is more problematic. Subsequent surveys of farmers
in the same area of the cotton zone, confirmed by unpublished CRS estimates, show
a large, even increasing, proportion of wheat area under Blue Silver. Perhaps the
cluster sampling problem is even more severe for the breeders' survey than the
survey of farmers; and, as in Mardan, both WL-711 and Blue Silver may be referred
to as "India" by farmers, although the name more commonly applies to WL-711.
Current Estimates of Varietal Coverage
Estimates from the Crop Reporting Services and special studies-Though
some wheat varieties are more widely adapted than others, different varieties are
often more popular within different cropping systems. An obvious example is the use
of certain varieties in irrigated agriculture and others in rainfed agriculture.
Different requirements for maturity and disease resistance also account for varietal
diversity over widely dispersed areas. For those reasons, and also because of
differences in recording methodology, the Punjab-wide varietal estimates from the
CRS cannot be compared directly with those from the special studies, which covered
a much smaller area. Nonetheless, examining the different estimates for some of the
major varieties together helps identify regional differences in varietal use (Tables
3.2 to 3.4).
The estimates from the special studies for 1985/86 and 1986/87 are broadly
consistent with the CRS estimates for the same years. In particular, both indicate
that Pak-81 is undergoing rapid adoption and Yecora is nearly phased out. Two other
results from the special studies might be predictors of province-wide trends: namely,
that WL-711 and Punjab-81 probably reached their peak coverage in the years of the
studies and are likely to have entered the disadoption phase.
7 In fact, in Mardan "India" might refer to either WL-711 or Blue Silver, as both
WL-711 and Blue Silver's sister line, Sonalika, were imported from India. Here,
"India" has been recorded under WL-711; otherwise the discrepancy for WL-711 in
Mardan would be even greater.
Besides indicating general trends in varietal use and disuse, the special studies
provide specific evidence of preference for particular varieties in the three crop
production zones. Pak-81, Punjab-81, and Yecora are clearly important in the rice-
wheat area, whereas WL-711 and Bahawalpur-79 are much more significant in the
cotton-wheat area. Blue Silver is important in both zones, but particularly in the
cotton-wheat area. WL-711 performs well when planted late, and Blue Silver has
traditionally been recommended for late planting. Although WL-711 has been
Table 3.2. Percentage area planted to major wheat varieties in the Punjab,
1985/86 and 1986/87
Variety 1985/86 1986/87
Pak-81 9 17
Punjab-81 14 15
Blue Silver 14 12
Bahawalpur-79 2 2
WL-711 18 20
Yecora 12 8
Source: Crop Reporting Service, Lahore
Table 3.3. Percentage area planted to major wheat varieties in the rice-
wheat survey area, 1985-89
Variety 1985/86 1986/87 1987/88 1988/89
Punjab-85 -- -- 5
Pak-81 26 38 50 55
Punjab-81 17 7 7 6
Blue Silver 10 11 5 6
WL-711 2 -- 1
Yecora 10 8 2 3
Source: Agricultural Economics Research Unit, Faisalabad
Table 3.4. Percentage area planted to major wheat varieties in the cotton-
wheat survey area, 1985-89
Variety 1985/86 1986/87 1987/88 1988/89
Pak-81 6 11 11 17
Punjab-81 9 5 14 7
Blue Silver 21 22 27 35
Bahawalpur-79 12 9 12 9
WL-711 37 29 24 14
Yecora 1 1 -- 2
Source: Agricultural Economics Research Unit, Faisalabad
banned since 1982, and although the Varietal Evaluation Committee has
recommended that Blue Silver be phased out, the actual choice of varieties in the
cotton zone has been determined by the constraints of the cropping system rather
than by recommendations based largely on disease resistance.
Recent trends in varietal use in the special study areas-Data from three
years of farmer surveys in the rice-wheat zone, cotton-wheat zone, and Mardan
illustrate patterns in varietal use and identify trends among varieties in each zone.
Some distinctions will be made in those data. First, "new varieties" in any year are
defined as those released no more than five years ago. Second, in any year, varieties
are classified as "recommended" or "banned" according to the list issued after the annual
meeting of the wheat Varietal Evaluation Committee." On the basis of those two
definitions, varieties are classified as "new recommended," "old recommended," or
"banned." A third category, "all varieties released in 1979 or more recently," is the
basis of the study of the diffusion of new wheat seed and new wheat varieties,
presented in Chapters 5 and 6.
In the rice zone the wide diffusion of post-1978 releases (Table 3.5) is the result of
farmers' adoption of Pak-81. The "new, don't know" category has also increased in
area, implying that one or more recent releases are being adopted fairly rapidly. The
area under Punjab-81 appears to be declining and Yecora can be considered nearly
phased out. Although the large variability in the estimates makes it difficult to
speculate about varieties that cover smaller proportions of the area, figures for
1987/88 suggest that the area planted to Blue Silver may also be declining.
Table 3.5. Changes in the percentage area of recommended and other wheat
varieties, rice zone, Pakistan, 1985-89
Varietal group 1985/86 1986/87 1987/88 1988/89
New recommended 31 48 3 8
Old recommendeda 26 23 79 78
Banned/mixed 43 29 18 14
Post-1978 releases 49 55 76 80
a New varieties are those released no more than five years before the survey.
Recommended varieties are those recommended by the Varietal Evaluation
Committee. "Don't know" responses divided into "new, don't know" and "old, don't
know" on the basis of subsidiary questioning.
8 The Varietal Evaluation Committee is made up of wheat scientists from PARC as well
as from provincial wheat research networks.
In the cotton zone, the adoption of post-1978 releases has been much slower. Pak-81,
Punjab-81, and Bahawalpur-79 appear to make up nearly equal proportions of that
category. On the other hand, there has been a significant shift out of banned
varieties into recommended varieties in the most recent year (Table 3.6).
In Mardan, the relative area planted to old varieties is particularly high compared to
the other two study areas. Mardan has relatively little area planted to varieties
released in the 1970s and still recommended (Table 3.7). The increase of
recommended varieties in Mardan has been overwhelmingly the result of the
diffusion of Pak-81. The area under "new, don't know" varieties has been particularly
high in the last two years, implying that, although the estimated area under Pak-81
Table 3.6. Changes in the percentage area of recommended and other wheat
varieties, cotton zone, Pakistan, 1985-89
Varietal group 1985/86 1986/87 1987/88 1988/89
New recommendeda 19 27 3 1
Old recommended 35 32 71 81
Banned/mixed 46 41 26 18
Post-1978 releases 31 36 43 44
a New varieties are those released no more than five years before the survey.
Recommended varieties are those recommended by the Varietal Evaluation
Committee. "Don't know" responses divided into "new, don't know" and "old, don't
know" on the basis of subsidiary questioning.
Table 3.7. Changes in the percentage area of recommended and other wheat
varieties, Mardan, Pakistan, 1985-88
Varietal group 1985-86 1986-87 1987-88
New recommendeda 24 40 3
Old recommendeda 17 5 51
Banned/mixed 59 55 46
Post-1978 releases 24 40 47
a New varieties are those released no more than five years before the survey.
Recommended varieties are those recommended by the Varietal Evaluation
Committee. "Don't know" responses divided into "new, don't know" and "old, don't
know" on the basis of subsidiary questioning.
in Mardan is about 30%, the true proportion may be closer to 45%. The latter
percentage would make the diffusion of Pak-81 in Mardan comparable to its spread
in the rice-wheat area.
Recommendations for Monitoring
Several measures could improve identification of varieties in farmer surveys in
Pakistan and elsewhere. First, more distinctive varietal names could be chosen.
Second, enumerators should be trained to record "don't know" responses and local
names; farmers should not be prompted with the name of a variety that the
enumerator knows. Sampling designs could also improve. If cluster sampling is used,
more clusters with fewer farmers per cluster would improve sampling efficiency, as
varietal use tends to be correlated over short distances." However, large-scale
varietal monitoring is likely to remain a byproduct of other surveys, notably those
intended to estimate wheat production and yield. Agencies that monitor varieties,
such as Pakistan's Crop Reporting Services, should be consulted to determine if their
current sampling designs could, with minimal modifications, produce useful
estimates for major cropping systems within large areas.
Estimates of wheat varietal coverage should be circulated rapidly and widely to
policy makers, wheat breeders, and pathologists. In Pakistan, disseminating these
data in February or March would allow more in-depth assessment of the current crop
and assist the Varietal Evaluation Committee and the Federal Committee on
Agriculture to recommend varieties and set seed production targets. Furthermore,
CRSs in provinces other than the Punjab should be encouraged to collect and report
varietal data; varieties should be identified following guidelines suggested above.
Finally, special studies may occasionally need to be done in areas of interest to
pathologists or epidemiologists. The special studies reported here, if they are
continued, will allow longitudinal analysis of varietal change within particular
cropping systems. They will prove particularly useful if they are integrated with
analyses of other changes, both in wheat technology and within the cropping
9 For example, data from the studies reported in this chapter show that planting of
new varieties tended to be concentrated in some villages rather than to be spread
evenly over most of the villages.
10 For example, studies conducted by the Agricultural Economics Research Unit,
Faisalabad, and the PARC/CIMMYT collaborative program, have looked at the rapid
spread of an earlier maturing basmati rice variety, and the use of combine
harvesters by larger farmers, in the rice-wheat zone (Sharif et al. 1989; and Smale
1987, respectively). These changes may affect the choice of wheat varieties as they
imply somewhat earlier planting dates for wheat.
Wheat Seed Production and
Marketing in the Punjab and NWFP
M. Aslam Chaudhry, Paul W. Heisey, and Munir Ahmad
Recommendations on priorities for varietal development are not likely to succeed
unless the goals of the research program are integrated with those of the seed
production and marketing system. Without sufficient seed of recommended resistant
varieties, farmers simply cannot reduce their losses from rust diseases. This chapter
describes seed production in Pakistan, focusing again on the Punjab and also briefly
on NWFP, to see how the system has improved in the past and determine how it can
be made more effective in the future.'
The Wheat Seed Industry in Historical Context
Increased government involvement in procuring and distributing seed in Pakistan
began with the establishment in 1961 of the Agricultural Development Corporation
(ADC). The quantities of wheat seed sold during the ADC period are shown in Table
4.1. On average, that seed was enough to cover 2-4(/ of the total wheat area in
Punjab Province, although substantial amounts of seed were sold in the late 1960s
when seed of high-yielding varieties was first imported from Mexico.
Under the ADC, pre-basic seed produced at government research institutes was
multiplied into basic seed at ADC farms. Basic seed was multiplied into certified
seed at registered growers' farms
and then offered for sale to
Table 4.1. Wheat seed sold in the Punjab farmers. However, coordination
Province during the Agricultural between the research institutes
Development Corporation period, 1965-73 .
and the ADC was limited. The pre-
Wheat Certified seed basic seed provided to ADC was
seed sold as percent of total often insufficient and substandard;
Year (000 t) seed requirements the contract multiplication system
1965/66 12.2 3.3 existed in name only.
1965/66 12.2 3.3
1966/67 15.5 4.0
1967/68 38.9 9.1 Because of alleged malpractices
1968/69 24.2 5.3 and seed mixing during its first few
1969/70 8.8 2.0 years, the ADC was not permitted
1970/71 6.7 1.5 to commission agents for
1971/72 9.7 2.3 marketing seed and had to set up
1972/73 17.0 3.9 its own network of 47 bulk centers
and 212 retail points throughout
1 A fuller treatment of this subject can be found in Chaudhry and Heisey (1987). The
cooperation of Chemonics International Consulting Division in supporting this
research is gratefully acknowledged.
the country. Staffing problems led the ADC to recruit employees from the military,
but they lacked agricultural experience. Seed targets were established arbitrarily
with little reference to market demand.
These inadequacies combined to make the quantity and quality of seed offered for
sale to farmers unacceptable. The ADC was dissolved in 1972 and its functions
relating to seed production and marketing were assumed by the provincial
governments. In Punjab Province, Punjab Agricultural Development and Supplies
Corporation (PAD&SC) took over most of ADC's assets and staff and continued
Unfortunately the new organizational structure did not rectify the problems that
brought about ADC's failure. To replace the seed production system with a modern
seed industry that would release new varieties and multiply, process, certify, store,
and market seed, the government initiated a Seed Industry Project in 1976 with the
financial and technical assistance of the World Bank. The main benefit anticipated
from the project was the higher crop yields to be obtained by users of improved
quality seed. To implement the project, provincial seed corporations were established
in the Punjab and Sind. One of them, the Punjab Seed Corporation (PSC), now
markets seed for 12 crops, although cotton and wheat seed are by far its dominant
The Present Seed Production System in the Punjab
The PSC produces pre-basic wheat seed at the research institutes or at the
Foundation Seed Cell, Khanewal. Pre-basic seed is multiplied into basic seed at the
PSC farms and supplied to registered growers contracted by the PSC to produce
certified seed. At all stages of seed multiplication, standing crops are inspected by an
independent agency, the Federal Seed Certification Department (FSCD). Seed is
procured only from fields approved by the FSCD. That agency also tests the purity
and quality of seed during processing and distribution. In addition to the routine
seed certification tests of the FSCD, the PSC has established its own Internal
Quality Control Cell at each plant site. This system also tests seed at the fields of
registered growers, in their stores, and at PSC plant sites or stores.
Pre-basic seed production-Pre-basic seed of impeccable quality is essential to a
successful seed program. In Pakistan, pre-basic seed is produced at the research
institutes two years ahead of the certified seed crop, under the direct supervision of
plant breeders. To handle pre-basic seed production adequately, the research
institutes have been provided with sophisticated laboratory equipment under the
Seed Industry Project.
Because pre-basic seed is produced two years before the certified seed crop,
production in year t depends upon certified seed requirements in year t+3. Certified
seed requirements depend upon anticipated seed demand and rate of seed
replacement.2 In the early years of the Seed Industry Project, breeders lacked
resources to produce the quantities of pre-basic seed that were required. To meet the
anticipated demand for certified seed, it was decided to produce two generations of
basic seed at the PSC farms (2,370 ha in three farms at Khanewal and 70 ha at
Sahiwal). This increased the certified seed production cycle from three years to four.
To shorten the cycle, a "Foundation Seed Cell" was established in 1980/81 at the PSC
seed farm in Khanewal to produce pre-basic seed under breeders' supervision. In the
first three years of the Foundation Seed Cell program, the PSC share in pre-basic
seed production increased from 20-4017 to over 90% from 1983/84 onward.
Basic seed production-Basic seed is the progeny of pre-basic seed. To ensure the
closest possible control over production and handling, basic seed is produced on PSC
farms. The PSC, after taking over the farms, levelled the fields and provided such
resources as tubewell irrigation, tractors, agricultural machinery, and management
and technical guidance for the tenants.
Area sown to pre-basic seed and total basic seed production are shown in Table 4.2.
Each variety's share in the total basic seed production plan has changed over the
years as new varieties have been introduced." Sandal, Lyallpur-73, LU-26, and Pari-
Table 4.2. Production of basic wheat seed at Punjab Seed Corporation farms
Pre-basic Area sown Basic seed
seed for basic seed production Yield
Year (t) (ha) (t) (t/ha)
1976/77 2.8 52 183 3.51
1977/78 5.9 79 291 3.68
1978/79 19.6 273 991 3.63
1979/80 6.8 128 456 3.58
1980/81 8.3 86 313 3.63
1981/82 15.2 155 610 3.93
1982/83 7.2 46 202 4.42
1983/84 31.5 132 436 3.31
1984/85 114.2 685 2,569 3.75
1985/86 153.6 617 1,834 2.96
2 See Chaudhry and Heisey (1987) or the project documents (World Bank 1976; PSC
1977) for assumptions used in planning the Seed Industry Project. They imply, very
roughly, a certified seed requirement of 70,000 t/yr for the Punjab. Using fairly
conservative assumptions about seed multiplication ratios, this implies production of
25-40 t of pre-basic seed each year.
3 Details of pre-basic and basic seed production for each year by variety can be found in
Chaudhry and Heisey (1987).
73 dominated the PSC seed multiplication program during its early years when total
output was lower than at present. More recently, Pak-81, Punjab-81, and Blue Silver
have been the leading varieties featured in the seed production plan.
Certified seed production-To improve reliability of seed supplies and minimize
managerial problems, farmers selected by the PSC to produce certified seed must
meet certain standards. The criteria for selection are:
* The grower should be cooperative, reliable, financially sound, and prepared to
adopt recommended farm development and crop production practices;
* The farm unit of the grower/family should be at least 40 ha and preferably directly
* Farms should be near the seed processing plants. (Progressive growers with large
mechanized farms located farther from processing plants are chosen occasionally.)
There are currently 572 PSC-registered growers, 310 in category "A" and 262 in
category "B." The PSC enters into contracts with category "B" growers only if the
total production target is beyond the capacity of its category "A" growers. During
recent years, certified wheat seed was produced on an average of 19,000 ha of
category "A" farmers' land and 13,000 ha belonging to category "B" farmers.
The quantities of wheat seed procured from registered growers are shown in Table
4.3, along with annual targets fixed by the government and targets planned in the
original PC-I (Seed Industry Project) scheme. Production of certified seed for four
individual varieties widely grown by farmers is also shown.' The total amount of
wheat seed procured by the PSC rose from 4,000 t in 1979/80 to 43,000 t in 1986/87.
Most of this increase in certified seed procurement occurred in the PSC's first five
years; it has levelled off since 1983/84. The total amount of "improved wheat seed"
reported as distributed in the Punjab doubled from 1979/80 to 1986/97, from 22,000 t
to the current figure (Government of Pakistan 1983). It appears that in the early
years of PSC operation PAD&SC was distributing seed that was not produced by the
The PSC fell short of procurement targets every year except for 1979/80 and 1982/83,
when it sold all the seed it procured. In 1979/80 the procurement target was very low
compared to following years. It was PSC's first year in the market and marketing
4 Further details of certified seed production by variety can be found in Chaudhry and
5 It is unlikely that much of the non-PSC seed distributed was certified by the FSCD. as
this agency was established by the Seed Act of 1976 and was probably not fully
operational until the 1980s.
efforts were substantial in relation to the amount of seed procured. The year 1982/83
was good because seed of WL-711 and Punjab-81 was in great demand, and PSC
stocks consisted mainly of those varieties.
The procurement targets from 1979/80 to 1981/82 were very much in line with those
planned in the Seed Industry Project appraisal report (PC-I). But in 1983/84 and
thereafter, targets fixed by the government and quantities actually procured were
significantly below the targets planned in the PC-I scheme.
The relationship between amounts of certified seed procured for the four varieties
listed in Table 4.3 and the area covered by those varieties is shown in Figure 4.1.
The same scales are used in each part of the figure. The figure indicates that seed of
those four varieties continues to spread although certified seed production has
diminished or stopped. For the older varieties Blue Silver and WL-711, it is difficult
to establish the amount of time between seed production and significant area
coverage, especially since some seed of those varieties was probably first distributed
outside of the PSC network. For the more recent releases Pak-81 and Punjab-81,
area seems to have increased rapidly about two years after the first large increases
in seed production.
Multiplication Capacity and Initial Multiplication Decisions
In many seed multiplication schemes, particularly in the earlier stages of production
of basic and pre-basic seed, seed rates are lower than those usually chosen by
farmers (Hanson et al. 1982). The aim is not to maximize biological yield (or
economic profit) but rather the ratio of seed output to seed input. Though greater-
than-normal quantities of other inputs may maintain yields (Brennan and Appleyard
1982), some yield reduction is also a possibility.
Table 4.3. Certified wheat seed production (tons), Punjab, Pakistan
1979/ 1980/ 1981/ 1982/ 1983/ 1984/ 1985/ 1986/
80 81 82 83 84 85 86 87
Total 4,100 11,500 19.800 33,300 44,200 48,500 44,500 43,300
target 4,100 14,900 22,400 29,900 44,800 52,300 52,300 48,500
target 4,100 14,900 22,400 26,100 62,200 62,200 62,200 62,200
Pak-81 -- 356 8,790 25,200 24,100 20,100
Punjab-81 80 562 964 8,530 18,700 10,600 8,290 8,940
Blue Silver 87 1,520 3,910 7,440 10,400 8,920 8,940 11,900
WL-711 394 1,750 7,070 8,200
5 / unde
79/80 81/82 83/84 85/86
79-80 81-82 83-84 85-86
79-80 81-82 83-84 85-86
79-80 81-82 83-84 85-86
Figure 4.1. Certified seed production and varietal diffusion for
four varieties, 1979-87.
The data in Tables 4.2 and 4.3, as well as data for individual varieties, indicate that
implied multiplication ratios from pre-basic to basic seed and from basic to certified
seed vary greatly from year to year. Furthermore, multiplication ratios from pre-
basic to basic seed are often rather low. The fairly good yields in Table 4.2 indicate
that some aspects of production were carefully managed on the PSC seed farms. On
the other hand, seed rates implied by the second and third columns of the table are
often high, even higher than "normal" seed rates for irrigated wheat in Pakistan.
One explanation is that some of the pre-basic seed does not meet standards for basic
seed production. Another possibility is that some pre-basic seed is diverted from
basic seed production, either because production plans for varietal mix change or for
other reasons. Data for some popular varieties, notably Pak-81 and Punjab-81, also
show rather low multiplication ratios, implying that diversions are not the result of
changes in production plans.
It seems that the main cause of fluctuating multiplication ratios from basic to
certified seed is that the amount of certified seed procured is mainly determined by
the government's procurement target and PSC's perception of how much seed it can
sell, rather than by the amount of basic seed available from the previous production
cycle. In years when the ratio of certified to basic seed is low, either some basic seed
does not go into certified seed production, some seed produced by registered growers
does not meet certification standards, or seed produced by registered growers is
simply not procured by the PSC. On the other hand, in years when the apparent
ratio of certified to basic seed is high, the PSC may have procured certified seed
indirectly from farmers who were not issued basic seed for multiplication under
contract, if the seed they produced met certification standards.
Given the area PSC now has available for basic seed production and the number of
its contract growers, the corporation clearly has the capacity to meet total wheat
seed production targets. But the PSC generally follows a conservative approach and
procures only as much seed as its managers feel can be sold, with some reference to
the annual seed production targets fixed by the Federal Committee on Agriculture.
The targets are generally based on the amount of seed sold and on targets assigned
in the previous year. The PSC is not a member of the Federal Committee on
Agriculture, and constraints faced by the PSC in procuring and selling seed are not
taken into account when targets are set. Too high a procurement target can lead to
procurement of seed that does not meet seed certification standards or is of
The PSC can now make 8,000-9,000 t of seed of individual varieties available to
farmers three years after release (as it did with Pak-81) or even two years after
release when release seems to have been anticipated (Punjab-81). There may be
several ways to increase seed production capacity, but doing so requires early
decisions about which varieties to multiply. Past coordination of varietal choice
between the government and the PSC has not been encouraging; procedures for
selecting, retaining, and withdrawing varieties for seed multiplication and
distribution have not been understood clearly by all parties. Although the seed
production cycle takes three to four years, decisions to retain or reject a variety are
For example, in 1981/82 the Ministry of Food and Agriculture (MINFA) and PARC
recommended that Blue Silver, Bahawalpur-79, Sandal, Pari-73, and Indus-79 be
grown for only one year, and only in specified limited zones.' But the next year PSC
was asked to multiply those varieties again, because replacements for them were not
forthcoming. In another instance, during 1981/82 the variety WL-711 was not
allowed to be distributed because it had been banned, but PSC had to procure it
because it was already planted with contract growers.
One reason for the PSC's conservatism in multiplying recently released varieties is
that breeders and the seed corporation have limited knowledge of a variety's
acceptability to farmers. Breeders attempt to evaluate promising materials by
planting them in microplots in farmers' fields. After that, lines proposed for release
are tested for two years in the National Uniform Wheat Yield Trials (NUWYTs). Plot
sizes in the microplot trials and the NUWYTs are too small for farmer evaluation.
Also, for breeders to evaluate the materials properly, the level of management must
be somewhat more intensive than the management farmers usually provide. Since
farmers' reactions are not recorded, breeders and the PSC have little information
about a variety's commercial possibilities over a wide area.
Seed Processing and Quality Control
Seed processing includes drying, cleaning, grading, and packing. Under the Seed
Industry Project, three seed processing plants are to be installed, one each at
Khanewal, Sahiwal, and R.Y. Khan. Each plant will have the capacity to process
about 27,600 t of wheat seed. The plant at Khanewal has been in operation since
1985, but the other two are not yet functional. In the meantime, the PSC uses other
processing methods, such as cleaning wheat seed with locally made sieves.
Total planned storage capacity in open storage and silos will be about 43,000 t.
Currently the PSC stores about 22,000 t of wheat seed annually in its own facilities
and hires warehouses, some of which cannot be fumigated properly, for storing the
The Industry Council for Development (ICD) report on Pakistan's seed industry
(1987) notes that the assumption that a seed certification law addresses all
consumer protection issues is not justified. The apparent lack of consumer protection
laws at the retail level provides merchants with the opportunity to mix noncertified
seed with high-quality certified seed. However, despite current problems with seed
6 Indus-79 never achieved commercial success.
processing and quality control, two recent studies conducted by the Punjab Economic
Research Institute (PERI) and the PSC (Sharif et al. 1986; PSC 1986) indicate that
80% or more of farmers sampled throughout the Punjab were satisfied with the
quality of seed supplied by the PSC. The PERI study referred specifically to wheat
seed. The PSC results might be biased positively both because the quality of cotton
seed produced by the PSC is exceptionally good and because the survey was done by
PSC field staff, who were also responsible for procuring and distributing seed. Even
though few consumers appear to complain about the quality of PSC wheat seed,
consumer protection measures should be strengthened.
The distribution network-The PSC sells its seed through public and private
organizations. At first the PSC used the retail outlets of PAD&SC, but as it
expanded it began selling seed through private dealers, its own outlets, and branches
of the Provincial Cooperative Bank. The PAD&SC also markets seed through private
dealers who are primarily agents for PAD&SC fertilizers.
Between 1981 and 1986 the number of PSC outlets increased from under 400 to over
900. These may be viewed as potential outlets, as the amount of seed handled per
outlet varies widely. The largest market share in 1985/86 was held by PAD&SC,
which handled 59% of PSC wheat seed sold in the Punjab. These sales were made
through 186 PAD&SC sale depots as well as some of the 581 private dealers carrying
PSC seed. The rest of the private dealers, who receive seed directly from the PSC,
accounted for 27% of the Punjab market. Most of the remaining seed, approximately
14%, was sold by 11 PSC sale depots located either at seed processing plant sites or
divisional headquarters. Although 140 Cooperative Bank branches supposedly
handle PSC seed, less than 1% of the seed sold was marketed through the bank.
A geographic breakdown of sale points shows that private dealers and PSC depots
are concentrated in the cotton zone, suggesting that PSC depots are more likely to be
located in areas where a more profitable product, cotton seed, can be marketed. The
concentration of PSC depots (6 out of 11) in the cotton zone is also influenced by the
fact that PSC farms and seed processing plants are located there.
The PAD&SC has had difficulty establishing itself as an effective institution for
marketing agricultural inputs. Its market shares for its two major products,
fertilizer and seed, have declined with time because of the private sector's increased
involvement in marketing inputs. That trend has led the PAD&SC to reduce its sale
points by about half in recent years and has diminished the PSC's enthusiasm for
selling its seed through the PAD&SC network. But it is awkward for PSC to decline
to use PAD&SC as its distributing agent: the two organizations share the same
Chairman and Board of Directors and the PSC has not developed an alternative
marketing arrangement although it has been in business for almost eight years.
Some of these problems are reflected in the dealings of the two public sector
organizations with the network of private dealers. A majority of the private dealers
selling seed are PAD&SC agents. When they come to PAD&SC stores to get
fertilizer, they are sometimes required to take seed as well. Private dealers who deal
directly with the PSC received a commission of Rs 12 per 90-kg bag in 1985/86, but
those selling seed for the PAD&SC received Rs 8 per 90-kg bag. The PAD&SC
retains the balance of the PSC commission to support its own operations.
Furthermore, these commissions, even after a 100% increase between 1985/86 and
1986/87, are still less than 5( of final product price. Commissions on fertilizer are
nearly 20%. The PAD&SC dealers are particularly unhappy with the situation.
Management of seed distribution-Before the selling season begins, the PSC
asks its dealers, private and public, about their anticipated demand and later
transports the seed to dealers' stores at its own expense in accordance with a
mutually agreed upon supply schedule. As the season proceeds, supplies are adjusted
depending on the market.
Seed is supplied to public sector agencies and private dealers on a "cash and carry"
basis as a matter of policy, but in practice the requirement is usually relaxed for
public sector agencies. Some private dealers who have established their
creditworthiness with the PSC also receive seed on credit against guarantees.
The PSC pays the same rate of commission to all distributing agents with whom it
deals directly. If some of the stocks supplied to distributors are not sold, PSC takes
them back at its own expense and refunds the dealers. The PSC is considering
ending this policy to avoid transportation costs, but such a change would discourage
PSC agents from requesting more seed. Already some dealers state that the PSC is
reluctant to take back unsold stocks.
Most dealers handling PSC seed are dissatisfied with the corporation's seed
distribution. Poor planning and coordination between the marketing staff and stores
staff mean that seed supplies are often delayed, quantities dispatched sometimes
exceed quantities requested, or seed is sent to a geographic zone for which it is
inappropriate. The quality of packing material is reportedly very poor. All of these
factors negatively affect the total sales volume at the retail level, compounding the
problem of unsold stocks.
All marketing activities of the PSC are supervised by the staff of the Marketing
Division, where one assistant manager is presently responsible for monitoring seed
sales in three districts. If sales are to be supervised effectively, the number of
marketing field staff must be increased, as this area is too large for one person to
Total sales-Presently, the PSC produces approximately 44,000 t of wheat
seed-about 70% of the demand for certified seed planned in the original project and
about 9% of the total annual provincial demand (Table 4.4).' Ten percent of annual
demand might not be too different from wheat seed production in other parts of the
world (J. Longmire, personal communication).
In the early years of the PSC, almost all of the corporation's wheat seed was sold in
the cotton-wheat zone, particularly in Multan Division. The proportion of seed sold
in that zone has fallen steadily but, even in 1985/86, Multan and Bahawalpur
Divisions, with 30% of the total Punjab wheat area, accounted for 43% of PSC wheat
seed sales. The concentration of both seed production and retail outlets in this area
is certainly responsible for the zone's large share of sales.
Even though it obtains quantities of seed smaller than the targets assigned by the
government, the PSC in some years does not sell all the seed it procures and offers
the remainder for sale as grain in the open market. The PSC has been unsuccessful
in selling all its seed stocks for several reasons. First, procurement targets are set
arbitrarily. Second, the seed marketing system is inefficient. Improved marketing
requires greater coordination between units within the PSC and better planning of
which varieties to produce and where to market them. Finally, neither the seed
project planners nor PSC management have resolved the aims and principles of seed
pricing in the marketing process. The implications of this last problem are discussed
Table 4.4. Procurement and sale of Punjab Seed Corporation wheat seed
Year Target Procured Sold Balance
1979/80 4,100 4,100 4,100 0
1980/81 14,900 11,500 10,000 1,500
1981/82 22,400 19,800 19,600 200
1982/83 29,900 33,300 33,300 0
1983/84 44,800 44,200 41,100 3,100
1984/85 52,300 48,500 48,500 0
1985/86 52,300 44,500 41,000 3,500
7 Total sales figures include seed sold to other provinces and exported to other
countries. However, the quantities sold to other provinces and countries have been
small relative to total sales.
8 A breakdown of sales by districts within the Punjab can be found in Chaudhry and
Current pricing and subsidies-The PSC, like many other quasi-public
organizations dealing in seed, tends to base pricing decisions on costs. Before the
selling season, the PSC Marketing Division proposes the sale rate of seed, which is
usually approved by the Board of Directors. The sale rate is fixed to recover the
actual expenditure incurred in procuring, storing, and handling seed. To ensure the
PSC's financial viability, a corporation margin is added to the end price of seed.
Various cost items that enter into the calculation of the retail price of seed are
shown in Table 4.5. Although the procurement price of wheat has increased by 60%
since 1980/81 and the premium paid to contract growers has stayed constant during
the last five years, it is difficult to interpret changes over time in other costs. The
PSC distributes most of seed handling and other operating costs over wheat and
cotton seed, so one reason for irregular changes in the cost structure may be the
variation in total volume of wheat and cotton seed that is procured and sold.
Nonetheless, it is hard to understand why the corporation margin is charged in one
year and not in another; how it differs from corporation overheads; or how
distribution costs can stay constant over time when total quantities handled,
transportation costs, and wage rates are all increasing. Also, it is important to note
that the commission paid to dealers was Rs 12 per 90-kg bag instead of Rs 8, the
figure used in calculating the 1986/87 sale rate. This discrepancy may result from
inconsistencies noted earlier in the actual commission that is paid to the final
The price of wheat seed was subsidized for the first six years of the Seed Industry
Project. The government subsidy was gradually reduced after 1983/84 and ended
completely in 1986/87. There may still be a small element of cross-subsidization
within the PSC, which assigns a smaller share of corporation overheads to wheat
seed than to cotton seed because farmers are relatively more willing to pay for cotton
seed. Furthermore, the initial fixed costs of establishing seed farms and processing
plants are not reflected in the price of seed.
When farmers change wheat varieties, their willingness to pay for seed is fairly high.
However, for a given variety, incremental benefits associated with the use of certified
wheat seed may not always be enough to support a high seed-to-grain price ratio if a
farmer has only been planting a variety for a few years or can purchase fairly good
seed from a neighboring farmer. The PSC should recognize that, although it enjoys a
monopoly in the certified wheat seed market, it cannot increase the price of wheat
seed without adopting a more aggressive marketing strategy that emphasizes
The PSC does not have a marketing research unit and bases its seed production and
distribution plans on historical trends. Furthermore, no regular information is
collected about why one variety is preferred over another in a particular cropping
Table 4.5. Prices and costs of wheat seed (Rs/90-kg bag), Punjab, Pakistan,
1980/ 1981/ 1982/ 1983/ 1984/ 1985/ 1986/
Description 81 82 83 84 85 86 87
Procurement price 112.50 130.50 130.50 144.00 144.00 157.50 180.00
Premium to growers 9.67 11.25 11.25 11.25 11.25 11.25 11.25
Procurement cost" 16.57 15.36 14.11 15.12 15.75 15.14 13.86
Cost of jute bag 14.00 11.75 12.40 13.25 14.27 15.40 15.73
Sieving losses" 0.00 0.00 4.68 3.40 3.42 3.66 4.10
Distribution cost 7.10 7.10 7.10 7.10 9.48 10.99 8.30
Commission to dealer 5.00 5.00 5.00 5.00 6.00 6.00 8.00
Interest on capital 9.02 8.16 10.13 11.92 11.97 12.87 14.36
Corporation overheads 6.94 5.49 7.79 7.48 15.04 14.58 13.20
Corporation margin' 4.83 0.00 0.00 5.36 5.40 5.82 0.00
Total cost 185.63 195.03 202.96 223.88 236.58 253.21 268.80
Subsidy 15.63 18.03 18.03 18.03 11.56 6.21 0.00
Sale rate 170.00 175.00 185.00 205.00 225.00 247.00 269.00
a Includes filling, weighing, stitching, stacking, loading, unloading, transportation from
grower's field to plant site, storage, sieving, fumigation, transportation from plant to
stores, workcharge staff, taxes, and market fee.
b About 2% of "total procurement price" (procurement price + premium + procurement
c Transportation from PSC stores to dealers' store, loading, unloading, stacking, and
d Charged on "total procurement price" for six months. Interest rate used was 13% in
1980/81 and 1982/83; 10.5% in 1982/83; and 14% from 1983-84 onwards.
e About 3-5% of "total procurement price."
zone.9 Sales promotion is weak. The PSC has been in the business for nine years, yet
the brand name of its product has not been established. All of these factors suggest
the need to establish a strong marketing research unit capable of regularly
generating information and analyzing marketing problems. If such a unit is
established, a reorganization of existing procurement and marketing field staff
would be appropriate.
The Wheat Seed System in NWFP: Production and Distribution
The Agricultural Development Authority (ADA) of North West Frontier Province
(NWFP), which is also responsible for the supply of other agricultural inputs in
NWFP, organizes the production of certified wheat seed in the province. In theory,
the system works as follows. Pre-basic seed is provided by wheat breeders from the
research institutes, notably the Cereal Crops Research Institute (CCRI), Pirsabak.
Basic seed is grown on government farms run by agricultural extension. Certified
seed is produced by registered growers, who are private farmers. Both the Federal
Seed Certification Department and representatives of the ADA inspect the seed at
all stages of the process.
If growers clean seed, they receive a higher price premium. Both the growers and the
ADA primarily use hand sieves to clean seed. The ADA owns no storage facilities and
hires privately owned storage. Seed is fumigated, and though there are some losses
in storage, they have been minimal.
The ADA maintains some 25 to 30 sale points throughout NWFP. The amount of
wheat seed moving through these sale points varies widely. In recent years one-third
to one-half of the total wheat seed distributed by the ADA has passed through the
two distribution centers in Mardan District, the district covered in the surveys
reported in Chapters 3, 5, and 6.
The smooth flow of seed from pre-basic through certified production to the farmer is
often interrupted. Though the ADA sometimes cannot market a substantial portion
of the wheat seed it procures, in the recent past there has been a strong demand for
seed from various development projects in the province. This demand has led to seed
diversions before the certified stage, at times forcing the provincial research
institutes into the role of seed supplier."
9 During 1986 PSC did carry out a large-scale, farm-level survey to find out farmers'
preferences about seed varieties, packing sizes, and publicity media. Survey farmers,
who may have held somewhat more land than the average, were located throughout
the Punjab. Data were tabulated but no further analysis was made.
10 A fuller treatment of the NWFP wheat seed system can be found in Heisey et al.
11 This phenomenon has been more pronounced for maize seed than for wheat seed.
Total wheat seed procured by the ADA between 1982 and 1986 has been about 3,000
to 4,000 t (Table 4.6). Varietal procurement has concentrated on Pak-81; Blue Silver
and Lyallpur-73 are the other major varieties. Up until 1985/86, a substantial
proportion of this seed was bought from the Punjab Seed Corporation (PAC), but in
1986/87 the ADA was successful in obtaining its entire requirement from registered
growers in NWFP. The amount of seed procured has ranged between 4 and 57% of the
total annual wheat seed requirement of the province, comparable to the situation in
the Punjab in the late 1960s and early 1970s (Chapter 4).
Wheat seed targets for NWFP and the problems of unsold seed-Many
assumptions must be made in setting seed targets. Wheat seed is not replaced every
year because farmers maintain their own seed; a desirable target for seed turnover
might be every five years (Chapter 2). Farmers in rainfed areas are more likely to
grow older tall varieties for which seed is not supplied by the formal seed system.
Furthermore, the particular problems of marketing seed to small farmers make it
difficult to maintain much effective demand from the very smallest farmers. In
NWFP, a greater proportion of the wheat area is unirrigated than in any other
province; furthermore, farm size is much smaller than in the Punjab. These factors
suggest that a reasonable target for certified wheat seed procurement as a
proportion of total seed use might be lower in NWFP than in the Punjab.
There is no substitute for a thorough seed planning exercise. Nonetheless, applying
the same assumptions used in the PSC planning document (see Chaudhry and
Heisey, 1987)12 would imply an annual certified seed requirement for NWFP of
8,000 t. Reducing this amount by a further 25% to reflect the lower demand caused
by very small farm size and remote farm locations in NWFP suggests a target of
around 6,000 t per annum for wheat seed procurement by the ADA.
Table 4.6. Wheat seed (tons) procured and distributed in NWFP by the
Agricultural Development Authority
Variety 1982/83 1983/84 1984/85 1985/86 1986/87
Pak-81 54 2,138 2,170 2,450 2,041
Blue Silver 1,253 688 731 763 523
Lyallpur-73 454 543 270 344 464
Pirsabak-85 -- -- 116
Others 1,412 668 181 8 206
Total procured 3,173 4,037 3,352 3,565 3,350
Total distributed 3,069 3,402 2,959 2,254 2,945
Source: ADA, Peshawar
12 In particular, taking into account the high proportion of unirrigated land or the
lower percentage area planted to high yielding varieties in NWFP.
Seed production is, as noted, a somewhat greater constraint to the adequate supply
of wheat seed in NWFP than in the Punjab. Yet in NWFP, as in the Punjab, the
inability of the seed authority to market larger quantities of seed has also been a
major constraint to greater seed production. In 1985/86 one-third of the wheat seed
procured by the ADA remained unsold, leading to considerable concern among
provincial authorities, as unsold stocks are put on the open grain market. The losses
incurred are reflected in increases in the next year's seed price. In 1986/87, the gap
between procurement and distribution narrowed again, largely because of
substantial purchases by development projects. A single project alone took 30% of
the total provincial procurement. The provincial government also reinstituted the
practice of distributing some certified wheat seed through agricultural extension.
Seed Pricing in NWFP-Seed pricing is determined by adding storage and
distribution costs to the wheat grain price and the premium paid to the registered
growers. Despite this stated pricing
Table 4.7. Price of certified wheat seed, policy, seed prices in recent years
NWFP have been nearly identical to the seed
prices of the PSC (Tables 4.7 and
Rs/90-kg Seed-to-grain 4.5). This in effect must mean some
Year bag price ratio hidden subsidies, as the grain price is
generally higher in NWFP than it is
1984-85 243 1.44 in the Punjab. Furthermore, if the
1985-86 247 1.16 alternative to ADA seed is seed from
1986-87 266 1.24 the PSC, seed prices in NWFP should
tend to be higher because of
Sources: ADA, Peshawar; Agricultural tend to be higher because of
Economics Research Unit (PARC) at transportation costs. The higher
Tarnab, Peshawar grain price in NWFP also means the
seed-to-grain price ratio is lower in
a This figure is based on the price of grain NWFP than in the Punjab.
in Mardan District.
The system of multiplying and distributing improved wheat seed has changed for the
better in the Punjab under the PSC and in NWFP, but there is room for
improvement. Pakistan and other countries could benefit from long-term planning in
determining absent from seed production policy. Furthermore, coordination among
institutions that formulate policy and those that implement seed production
programs is essential. For example, since the seed production cycle in Pakistan
presently takes three to four years, seed production policy should be planned and
implemented accordingly. Possible changes in seed production planning include
streamlined varietal testing, multiplication of promising lines before they are
released as varieties, and greater coordination between the PSC, the Varietal
Evaluation Committee, and the Federal Committee on Agriculture.
Actual physical capacity to multiply seed is the least binding constraint faced by the
PSC, although production and processing might be improved. For example,
multiplication ratios could be improved either through changing agronomic practices
or reviewing quality standards to ensure they are not overly stringent. The location
of seed production farms could be diversified and seed could be increased out of
season. Unfinished seed processing plants should be completed. Because improved
marketing will increase seed demand, these physical production changes may
become more urgent in the future.
In Pakistan some possibilities for developing a well-coordinated, integrated, and
expanded seed marketing system include:
* Offering higher, uniform commissions to final sales agents;
* Relying more on private sector seed marketing;
* Relaxing the "cash and carry" condition to some extent;
* Closer PSC monitoring of its production and marketing costs;
* Experimenting with smaller packages, more distinctive packaging, and greater
* Taking more realistic approaches to seed certification and consume
* Improving coordination between various sections of the PSC, especially stores and
Conducting more regular market research.
Expanding the seed distribution network and offering greater incentives to retailers
will necessitate increasing the final seed price. Marketing margins will have to
become consistent with those presently offered for fertilizer in Pakistan and for seed
in other countries. Seed prices in Pakistan are currently low relative to grain prices.
The ratio of seed price to grain price is 1.5, compared to around 1.7 for developing
countries worldwide. In many Asian countries, including India, the ratio is 2 or more
(Gregg 1983; Singh 1985; Katyal 1987; Tunwar 1987), yet wheat varietal replacement
is faster in the Punjab of India than in the Punjab of Pakistan.l' Experiences in other
countries suggest that private dealers generally require a margin of 20% to
encourage them to participate in seed marketing. This is at least double what
dealers currently receive from PAD&SC.
13 Contract growers in India also receive higher premiums than in Pakistan.
Even if the price ratio were raised to 2 (for example, by paying 15% commissions to
retail dealers and registered growers), for farmers the desired time period for
replacing the varieties they grow would not rise to more than six or eight years
under reasonable parameter assumptions (Chapter 2). If higher seed prices make
seed more widely available and allow greater promotion of seed, it is highly likely
that the aggregate weighted mean age of varieties will decrease. Even if the varietal
life span favored by farmers were as high as eight years, mean age of varieties would
decrease if time between a variety's release and availability to farmers were reduced
to four years or less, an entirely reasonable goal for the seed system.
Farmers' Seed Sou
Khaleel A. Tetlay, Paul W. Heisey, Zulfiqar Ahmed,
and Munir Ahmad
Efforts to improve the pace of varietal replacement will benefit from information
gathered at the farm level to determine where farmers get the wheat seed they use,
where they get seed when they decide to change varieties, and how they manage seed
retained from their own fields.' Data for the study described in this chapter were
collected in 1986 during the survey of constraints to the rapid diffusion of new,
disease-resistant wheats. Social scientists from the Pakistan Agricultural Research
Council (PARC) administered detailed interviews to 146 farmers in the 30 villages
selected in the rice-wheat zone; 149 farmers in the 30 villages in the cotton-wheat
zone; and 99 farmers in the 20 villages in irrigated Mardan. (Survey locations are
depicted in Figure 1.1.) Further details about the surveys can be found in Tetlay et
Data from the three survey areas are broadly similar but nevertheless reveal certain
contrasts. Some differences relate to the fact that the seed system in North West
Frontier Province (NWFP) is more rudimentary than in the Punjab. Others relate to
contrasts between the two cropping areas in the Punjab (recall that seed production
and distribution in the Punjab is particularly concentrated in the cotton zone Seed
Table 5.1. Seed depot density (retail
seed outlets per 100,000 ha of wheat)
Punjab Province 15.1
Rice zone (Shekhupura,
Sialkot Districts) 8.8
Cotton zone (Multan, Vehari,
and Bahawalpur Districts) 22.6
Mardan District 2.1
Note: Cooperative Bank Outlets are not
included in the Punjab, since they
handle very little wheat seed.
depot density cannot be calculated
exactly for the three survey areas
because data on depots are only
available at the district level. However,
if we calculate density of seed outlets
for the districts where the survey areas
were located, the results confirm high
density in the cotton zone and low
density in Mardan (Table 5.1). Another
difference among the areas is that
newer wheat releases were more widely
diffused in the rice zone than in the
cotton zone at the time of the surveys,
largely because WL-711, a high
yielding, well-adapted but rust
susceptible variety, was dominant in
the cotton zone.
1 A more comprehensive account of this research can be found in Tetlay et al. (1987a)
and Heisey et al. (n.d.).
In this chapter and the next, "new varieties" at the time of the 1986 surveys are
those released in 1979 or thereafter, since those varieties were in most cases in the
initial stages of adoption. When the survey was taken, Punjab-81 had already been
banned north of Faisalabad because of stripe rust susceptibility (i.e. in the rice zone,
where it is grown, and in Mardan, where it is not), but it is included as a new variety
because the factors influencing its adoption resemble those influencing the adoption
of other new varieties.2
Farmers' Sources of Wheat Seed
In all three areas, the most common source of wheat seed planted in 1985/86 was
seed retained from the previous year's crop (Figure 5.1). Roughly one-fifth to one-
quarter of the farmers got their seed from other farmers. Some 10% or fewer
purchased seed at a depot."
An examination of some of the more popular varieties in each zone clarifies patterns
of seed acquisition. Obviously, farmers planting older varieties were more likely to
have been planting them longer and to be using retained seed. On the other hand,
farmers planting new varieties were more likely to have obtained their seed from a
seed depot. Some evidence indicates that the source of seed of new varieties, notably
Pak-81, was more often other farmers, whereas seed of old varieties was less likely
to be obtained from other farmers (Tables 5.2 to 5.4).
Initial Seed Sources for New Wheat Varieties
Patterns of seed acquisition become more evident if we look at farmers' sources of
seed for new varieties the first time they plant them. As expected, seed depots were
the major initial seed source for farmers in the two zones in the Punjab but were
much less important in Mardan, where the seed system is less developed. Looking at
all three zones together, it is apparent that other farmers were the source of seed for
about half the farmers who started growing a new variety (Figure 5.2).
Some farmers in Mardan first got seed of new varieties from research or extension.
The "other" category in Mardan usually refers to cases in which farmers said they
got seed at a depot, but did not know the depot's correct location; it is likely that
some of that seed came from research or extension.
2 In recent years, Punjab-81 has been declining in area in the rice-wheat zone both
because the PSC no longer makes its seed available there and because it has proven to
be particularly susceptible to shattering (see Chapter 3 and Chaudhry et al. 1985).
3 The "other" category for the two Punjab zones refers to farmers who got seed from a
variety of sources. In Mardan, the analysis was done by fields, so sources did not
S10% Seed depot
rUsI '.' a tI -
8% Seed depot
< 9% Seed depot
Figure 5.1. Seed sources for varieties currently planted.
Table 5.2. Sources of wheat seed of new varieties and other popular varieties
currently planted, rice zone
Percentage of farmers
Pak-81 Punjab-81 Blue Silver Yecora Sandal
Total 100 100 100 100 100
Table 5.3. Sources of wheat seed of new varieties and other popular varieties
currently planted, cotton zone
Percentage of farmers
Source Pak-81 Punjab-81 Bahawalpur-79 Blue Silver WL-711
Own 37 52 48 67 70
Other farmers 26 19 39 12 20
Seed depot 32 24 4 8
grain merchant -- 4 2
Other 5 5 4 10 10
Total 100 100 100 100 100
Table 5.4. Sources of wheat seed of new varieties and other popular varieties
currently planted, Mardan
Percentage of fields
Total 100 100 100 100
a "Mexipak" is often used as a generic name for semidwarf wheat in Mardan; it
usually refers to an older high yielding variety that the farmer has been growing for
a considerable time (Chapter 3).
56% / l 37 Seed depot
5% I 2%
- Urmers' new
S14C% Seed depot
Figure 5.2. Initial seed sources for new varieties.
Farmers who first acquired seed of new varieties from the depot tended to be larger
farmers (Table 5.5), whereas smaller farmers more often got seed of new releases
from other farmers. In Mardan, because of the smaller numbers involved, research
and extension are grouped with the seed depot as an initial source of seed
because they represent a formal institution rather than the informal but powerful
mechanism of farmer-to-farmer seed
Table 5.5. Farm size and percentage transfer.4
farmers using new varieties who
initially got w
heat seed from seed Farmers who supplied seed of new
h/extension varieties to other farmers tended to have
Farm size Farmers larger than average farms. Still, half or
(ha) (%) more of the farmers who initially
obtained new varieties from other
< 10 ha 22 farmers said their source was a farmer
> 10 ha 6 with less than 10 ha (Table 5.6). Source
< 10 ha 43
> 10 ha 6 farmers were also close to the farmers
< 10 ha 19 they served; over half the farmers who
> 10 ha 71 got seed from other farmers contacted
someone in their own village and over
/extension applies only to 80% received seed from a farmer within a
5-km radius (Table 5.7).
Table 5.6. Type of farmer from whom seed of new wheat variety was obtained
Percentage of farmers
Landlord 2 7
< 10 ha 66 47 58
> 10ha 32 46 42
Table 5.7. Distance to farmers providing seed of new wheat varieties
Percentage of farmers
Distance Rice zone Cotton zone Mardan
Same village 52 54 69
<5km 32 29 15
5-10 km 3 13 8
> 10km 13 4 8
4 In Mardan, farms are quite small so the 10-ha division between "small farms" and
"large farms" is less appropriate than in the Punjab. Forty-six percent of all farmers
with over 4 ha initially got seed of new varieties from a seed depot, research, or
extension, whereas 24% of the farmers with under 4 ha got new wheat seed from
these sources. It seems likely that in Mardan it is primarily the very largest farmers
who have contact with formal seed sources.
In all three survey areas, over 90% of farmers planting new varieties said they had
no problems obtaining seed. Three-quarters or more financed the seed with their own
money; the other significant way of obtaining seed was to exchange grain for seed
with another farmer (one-sixth to one-fifth of the farmers got their new seed that
way). Yet in both the rice and cotton zones, around half of the farmers who knew
about new varieties but had not planted them said seed was unavailable. This was
the most common reason given for not planting new varieties. In Mardan, the same
explanation was given by 9 of the 24 farmers who knew about new varieties but were
not planting them.
Farmers' Contact with the Seed Industry
About half the farmers in all three zones knew the correct location of the nearest
seed depot. Some farmers in each zone said they knew the location but did not
identify it correctly, an occurrence much more common in Mardan than in the
Punjab (Table 5.8). Mardan District has only two Agricultural Development
Authority (ADA) depots, one in Mardan and one in Swabi, although there are other
ways in which seed can be distributed. Significantly more farmers in the Punjab who
were aware of new varieties (they were already planting them or had heard of them)
knew the correct location of the depot nearest them. In Mardan, there was no
relationship between varietal awareness and accurate knowledge of the seed depot.
Over one-third of the farmers surveyed in the rice and cotton zones had actually
visited a seed depot whereas only one-fifth of the farmers in Mardan had done so
(Table 5.8). As farmers who had visited a depot are a subset of those who knew the
depot location, factors related to visits are likely to resemble factors related to
knowledge of the depot. In the Punjab, farmers planting new varieties were more
likely to have visited a seed depot. In Mardan, there was no relationship between the
Many variables can influence whether or not a farmer knows the location of the
nearest seed depot or visits it: human capital variables such as literacy; farm size
and tenure variables; information sources, such as agricultural extension; or
Table 5.8. Percentage of farmers who knew seed depot location and had
visited a depot
Rice zone Cotton zone Mardan
Knew correct location 51 46 52
Stated other location 14 11 38
Did not know location 35 44 10
Visited depot" 38 36 21
a Includes only farmers with correct knowledge of depot location.
distance from the depot. Variables used in the analysis reported below are defined in
Table 5.9. Since these variables are unlikely to operate independently, a variable-by-
variable analysis of relationships with knowledge of seed depots or visits to them is
likely to be misleading (Feder, Just, and Zilberman 1985). Instead, probit analysis,
which uses a number of independent variables, has been used to predict the
probability of whether or not a given farmer knew the location of the seed depot, and
also to predict whether or not the farmer had visited a depot.
Several equations were estimated for each of the three zones. Results of one of the
better equations for each zone (better in terms of goodness of fit as determined by the
regression chi-squared statistic) are presented in Tables 5.10 and 5.11." This
approach is not entirely satisfactory because there are likely to be causal
relationships between some of the explanatory variables. However, the results help
determine which variables are more likely than others to predict farmers' contact
with the seed depot.
Table 5.9. Variables used in probit analysis of knowledge of seed depot location
and visits to seed depot
AGE Farmer's age in years
LIT Dummy variable = 1 if farmer was literate
LNSIZE Natural logarithm of farm size in hectares
OWN Dummy variable = 1 if farmer owned some or all of the land he farmed
STATUS Dummy variable = 1 if farmer was a village or union council official,
government employee, member of a religious committee, member of a
cooperative society, or shopkeeper
EXT Dummy variable = 1 if farmer met with agricultural extension person-
nel in year previous to the survey
RADIO Dummy variable = 1 if farmer listened to agricultural programming on
the radio in year previous to survey
DEMO Dummy variable = 1 if farmer hosted or visited a wheat demonstration
DIS Distance (km) from a farmer's village to seed depot
5 Results of the equations presented in Table 5.10 and 5.11 were also checked for
consistency with the other estimated equations.
The results are consistent with our expectations, except for several anomalous
relationships in the smaller Mardan sample. Literacy is the key human capital
variable, positively related to knowledge of and visits to the seed depot in the rice
zone and in Mardan. In the cotton zone, literacy is not significant at standard levels
but the coefficient does have asymptotic t-values significant at the .20 level. In
Mardan, a quadratic age specification is also significant, implying that as a farmer's
age increases up to the mid-forties, the farmer is more likely to know where the seed
depot is or to have actually visited it; after that increasing age reduces the
Table 5.10. Factors related to correct knowledge of seed depot location, probit
n = 142
X2(7) = 36.3
n = 141
Note: Asymptomatic t-values in parentheses; *** indicates significance at 1% level;
** at the 5% level; and at the 10% level.
a Dependent variable is KNOW; dummy = 1 if farmer knew the correct location of the
seed depot nearest his village.
X(7) = 25.3
Extension contact is the main information source related to contact with the seed
depot. In the rice and cotton zones, farmers who had seen extension personnel within
the last year were significantly more likely to know where the seed depot was. In the
rice zone and Mardan, extension contact was significantly related to visits to the
seed depot. There was an anomalous result regarding information sources in
Mardan, where farmers who had listened to agricultural programming on the radio
within the last month appeared less likely to have visited the seed depot.
Table 5.11. Factors related to visits to seed depot, probit analysis
n = 146
x(5) = 42.2
n = 141
X2(7) = 21.3
Note: Asymptomatic t-values in parentheses; *** indicates significance at 1% level;
** at the 5% level; and at the 10% level.
a Dependent variable is VISIT; dummy = 1 if farmer had visited a seed depot.
n = 87
Variables related to general status or resource base, such as farm size, tenure, or
social status, are mostly insignificant or anomalous. Increasing farm size did appear
to increase the likelihood of seed depot knowledge in the rice zone, but the effect in
Mardan was negative. All in all, farm size bore little relationship to seed depot
knowledge or contact. This finding does not necessarily contradict earlier indications
that larger farmers planting a new variety for the first time were more likely to
acquire seed of the variety at a seed depot. What the present results seem to indicate
is that larger farmers have significantly higher levels of literacy and extension
contacts and, once these other variables are taken into account, farm size does not
have much of an effect one way or the other on their contact with the seed depot.
The most anomalous result is the highly significant negative effect of social status in
Mardan." Social status also appeared to be negatively related to depot visits in
Mardan, but positively related in the cotton zone.
In the cotton zone, where retail seed outlets are most concentrated, farmers located
farther from the depot were less likely to know where it was or to visit it. The
relationships were also negative in the rice zone, but not significant at standard
levels. There were no relationships in Mardan, where the formal seed system is a
much less active agent of varietal diffusion.
Management of Retained Seed
From year to year, the most significant source of wheat seed is seed that farmers
retain themselves. Farmers in the three surveyed areas were asked if they managed
seed crops any differently from the rest of their grain: did they select a special field
for seed, or thresh and store seed separately from other grain?
Farmers in the rice zone and Mardan were somewhat more likely than cotton zone
farmers to choose a separate field for seed, either before or at harvest. Over all three
zones, 40-50% of surveyed farmers threshed and stored seed apart from the rest of
their grain (Table 5.12). Threshing seed separately was the criterion for
determining if the farmer made special efforts to preserve seed quality. The few
farmers who stored seed separately without threshing it separately were not
included in the "special seed management" group for further analysis.
6 In Mardan, only 17 farmers had positive social status, a rather crudely defined
variable referring to farmers who were village officials, ran shops, and so on. Nearly
all of these farmers were literate. However, literate farmers without "social status"
were significantly more likely to identify seed depot location correctly than literate
farmers with status. Perhaps farmers with status were more familiar with non-ADA
seed sources such as research farms or extension offices.
7 When the social status dummy is left out of the estimating equation in the cotton
zone, the coefficient for literacy becomes significant at the .05 level, suggesting that
the "social status"' variable may be picking up some of the same influence as the
literacy variable did in the other zones.
Very few other characteristics of farmers could be related to whether or not they
used special seed management practices. In both the rice zone and Mardan, seed
management practices of farmers planting new varieties did not differ from practices
of farmers who did not plant them. Farmers in the cotton zone who planted new
varieties were significantly more likely to manage their seed to maintain quality.
Since few farmer characteristics were related to seed management on a variable-by-
variable basis, no probit analysis was done to predict whether or not a farmer would
thresh seed separately from grain. A few variables did appear to affect seed
management when analyzed individually. With increasing farm size, the likelihood
increased that farmers in the rice and cotton zones threshed seed separately; in the
rice zone and Mardan, farmers who had contact with extension in the last year
appeared more likely to thresh seed separately.
The evidence presented in this chapter confirms that the major source of wheat seed
is seed retained from the previous year's crop. The next most frequent source of seed
is other farmers. Less than 10% of farmers surveyed obtained seed at a depot. Fewer
than half of the farmers who retained their own seed sought to ensure its purity by
selecting or threshing it separately.
When farmers change varieties, other farmers are the most important source of seed.
In the Punjab, where the seed system is better developed, seed depots are almost
equally important as a source of seed when farmers want to change varieties. In
Mardan seed depots are much less significant as an initial source of new seed. In the
Punjab farmers planting new varieties are significantly more likely to know where
the seed depot is and to have visited it; in Mardan there is no relationship between
planting new varieties and contact with the seed depot. Farmers with larger
Table 5.12. Farmers' seed management practices for retained wheat seed
Percentage farmers using retained seed
Practice Rice zone Cotton zone Mardan
Kept separate field, threshed and stored
separately 17 7 15
Selected field at harvest, threshed
and stored separately 20 4 36
Threshed and stored separately only 7 26
Attempted to maintain seed purity 44 37 51
Stored separately only 4 3 3
Did not store separately 51 60 47
holdings are more likely to use a seed depot as the initial source of seed for new
varieties. Dispersing seed distribution points more widely would probably hasten the
spread of new varieties.
A number of associated farmer characteristics appear to influence whether farmers
know about or have visited the seed depot and whether they manage seed and grain
crops differently. The most consistent explanatory variables are literacy and contact
with extension. Farm size does seem to make a difference in one case-initial source
of new seed. Larger farmers may also be more likely to manage seed differently than
grain. With regard to seed policy it should be noted that more often than not new
seed enters a village when a larger farmer obtains it from the formal seed system.
Seed then spreads from farmer to farmer within the village or spreads to an
adjoining village. Farmer-to-farmer seed diffusion is highly localized, as fewer than
10% of farmers obtain seed from a village more than 10 km away. Despite the
strengthening of the formal seed production and distribution system, informal,
farmer-to-farmer seed transfer clearly remains a major means of diffusing seed, as in
the early days of the Green Revolution (Lowdermilk 1972).
-- Farmer Characteristics, Varietal Choice,
and the Spread of New Wheat Releases
Paul W. Heisey, Khaleel A. Tetlay, Zulfiqar Ahmed,
and Munir Ahmad
This chapter seeks to explain factors related to farmers' awareness and adoption of
newer wheat releases. Certain traits of farmers and varieties explain a two-step
process in which a farmer first becomes aware of new varieties and later adopts
Griliches' (1957) classic study of the spread of hybrid maize in the USA has been
succeeded by a vast literature on the adoption of agricultural innovations.: Much of
the literature concerns itself with the adoption curve, an S-shaped cumulative
frequency curve, which can refer either to the aggregate level or to individual
farmers.4 In Pakistan, adoption of high yielding varieties (HYVs) followed the classic
S-shaped pattern. But the replacement of individual wheat varieties is more
completely represented as a process of adoption and disadoption (Brennan and Cullis
1987), a pattern visible in Figure 2.2 (page 14) where the area covered by major
wheat varieties in Punjab is shown. During the adoption phase, the curve is similar
to the monotonically increasing curve usually studied.
In 1985/86, at the time of the adoption survey discussed in this chapter, cross-
sectional differences in farmers' awareness and adoption of new varieties were
distributed as in Table 6.1. The data in Table 6.1 are consistent with the area
estimates of Chapter 3, where it was noted that the spread of new varieties in the
Table 6.1. Farmers' awareness and adoption of new wheat varieties
Percentage of farmers
Rice zone Cotton zone Mardan
Planting total area to new varieties 27 22 14
Planting partial area to new varieties 27 20 14
Aware of but not planting new varieties 13 16 29
Unaware of new varieties 33 42 42
1 This chapter is partially based on material in Tetlay et al. (1987b and 1987c).
2 For a technical description of the type of model used here, see Maddala (1983).
3 This literature is summarized in Feder, Just, and Zilberman (1985).
4 At the aggregate level for a given innovation, the height of this cumulative frequency
curve at a given time can be measured in different ways. For individual farmers,
adoption curves show the degree to which the farmer uses the input(s) of interest.
rice-wheat zone was greater than in the two other areas at the time of the survey.
Farmers in the rice zone who grew new varieties tended to have grown them for less
than the average length of time; farmers in Mardan, for more. In other words, new
varieties appear to have diffused faster in the rice zone than in the other two areas, a
conclusion further supported by the aggregate data of Chapter 3. Diffusion of new
wheat varieties has been somewhat slower in Mardan because the seed system is
less developed. Although seed outlets are more heavily concentrated in the cotton
zone than in the rice zone, diffusion in the rice zone has proceeded faster because the
older varieties in the cotton zone are particularly well adapted to the zone's
environment and crop rotations.
Farmers' Perceptions of Wheat Technology
Perceptions of technological components for increasing wheat
productivity-In the 1985/86 adoption survey, farmers were asked to identify
which technological components were most important, second most important, and
third most important for increasing wheat yields. They did not identify variety as a
major component. Any attempt to determine which factors were most important to
farmers is subject to ambiguity because individual choices can be weighted
differently, but it is clear that in all three zones better land preparation ranked
highest and more fertilizer second. In the three zones, variety ranked between third
In diagnostic surveys conducted in the same zones (Byerlee et al. 1986), variety was
found to be one factor strongly affecting farmers' yields. For direct technology
transfer, variety was among the highest priorities in each area. The difference
between the relative importance attached to variety by researchers and farmers may
be related to several factors. First, differences in yield due to variety might not be
immediately evident prior to harvest. Second, seed is a relatively small amount of
farmers' production cost and farmers might tend to weight the importance of an
input in proportion to its cost. Finally, the fact that the new varieties were, in
general, diffusing slowly at the time of the study meant that farmers had relatively
few opportunities to compare yields of old and new varieties.
Farmers' perceptions of the disease threat-During the survey, farmers were
asked about major diseases affecting wheat; 70-90% of them were aware of rust. (In
the rice and cotton zones, about 90% mentioned smut, noted by only 55% of the
farmers in Mardan.) Of the farmers who knew about rust, half to three-quarters
called it "a problem" (Table 6.2). But even though many farmers knew about rust
and some thought it a problem, relatively few farmers in Punjab thought it could
recur. The different results for Punjab and Mardan were probably caused by the way
5 Farmers in Punjab were asked whether or not they agreed with the statement, "Rust
used to be a problem but it is no longer a problem;" in Mardan, they were asked
whether or not they agreed with the statement, "Rust could be a problem again in the
the question was phrased in the survey areas." This question probably influenced the
answers to subsequent questions about differences in varietal rust resistance and
loss of resistance over time.
One-quarter of the respondents in Punjab thought some varieties were more resis-
tant than others; in Mardan the proportion was a little less than half. In all zones,
half or less of the farmers who thought some varieties were more resistant than
others thought that resistant varieties could lose their resistance. Since more far-
mers in Mardan agreed with the statement on differential rust resistance, a simil-
arly larger proportion there thought resistant varieties could break down (Table 6.2).
Regardless of problems with some of the questions about rust, it is clear that in all
surveyed areas farmers' knowledge of disease was rather limited. Relationships
linking farmers' characteristics to disease knowledge variables were generally not
significant." Farmers' awareness of rust as a major problem would probably be much
greater in a year immediately following an epidemic. Similarly, awareness would be
greater among farmers growing a particularly susceptible variety in a year
immediately after that variety suffered noticeable yield losses from rust. But in a
relatively normal year some years after farmers have experienced serious losses
from rust, the threat of disease by itself is unlikely to motivate farmers to change
varieties, given the current state of their knowledge about varietal rust resistance
and rust epidemics.
Table 6.2. Farmers' awareness of the rust problem
Percentage of farmers
Rice zone Cotton zone Mardan
Mentioned/knew about rust 71 89 82
Thought rust was a problem some
years or every year 54 65 73
Thought some varieties were more
resistant than others 25 26 47
Thought resistant varieties could
lose their resistance 6 12 25
6 Nonetheless, in the rice zone and Mardan, farmers who planted or knew about new
varieties did seem more likely to believe that some varieties are more resistant than
others. In Mardan, literacy and extension contact seemed to be positively related to a
belief in differential varietal resistance; extension contact, radio contact, and social
status seemed positively related in the rice zone; and in the cotton zone, younger
farmers and farm owners appeared more likely to believe some varieties had greater
resistance. Given the very limited numbers of farmers who thought resistant varieties
could break down, in only one case did a farmer characteristic appear to affect this
belief: extension contact in the cotton zone. It is likely that in a multivariate analysis
the apparent significance of some of these variables might disappear.
Reasons for varietal choice-Variety was not the first factor farmers thought of
when they were asked what was most important for increasing yield. But when
farmers growing new varieties were asked why they had changed from old to new
cultivars, they cited yield more than any other reason (Table 6.3). The other
frequent responses for changing variety were yield decline or disease susceptibility of
the old variety; they are also related to a difference in yields. Some farmers who
noted that new varieties yielded better also mentioned the yield decline of old
varieties; unfortunately, data from two of the survey areas do not permit all factors
to be separated out. Even though farmers' awareness of disease is rather low, it is
worth noting that losses from disease are sometimes part of the yield comparison
that motivates varietal change.
When farmers planting old and new varieties were asked why they planted both
types, the most common response across all three zones was that they wanted to
compare the performance of each type. In addition, 30-40%c of the farmers in each
zone planted both types for reasons related to diversification: they wanted one
variety for late planting or one for home consumption, or simply wanted to avoid risk
(Table 6.4). Farm size was a highly significant determinant of the number of
varieties planted. In all three zones, mean farm size for farmers planting more than
one wheat variety was much larger than for farmers planting only one variety.7
"Objective" varietal characteristics and farmer behavior-everal
characteristics besides superior grain yield are often thought to influence farmers to
plant new varieties: straw yields (Husain 1987), taste and baking quality, and
resistance to moisture stress (Byerlee et al. 1986). To see if particular varietal
Table 6.3. Farmers' reasons for adopting new wheat varieties
Percentage of farmers
Rice zone Cotton zone Mardan
Higher yields 72 83 78
Declining yield of old variety 9 5 --
Disease susceptibility of old variety 9 7 4
Other 10 5 18
a Farmers sometimes mentioned declining yield or disease losses of the old variety as
well as higher yields of the new variety. However, in some of the survey areas it is
not possible to recover how many farmers mentioned these factors in conjunction
with higher yields.
7 Diversification over old and new varieties was one of the few ways in which farm size
did appear to affect varietal diffusion, if other variables were taken into account. See
characteristics had induced farmers to adopt new varieties, some "objective"
measures of varietal characteristics were examined along with evidence of farmers'
behavior regarding each characteristic.
Yield-Data from the ISWYN and Khanewal seed farm trials, analyzed in Chapter 2,
can be used to compare grain yields of several popular wheat varieties. At "normal"
planting dates, the new variety Pak-81 yields better than all other varieties
considered here. The old variety WL-711 also yields more than other important
varieties, and the old variety Sandal may also yield somewhat better. Four other
varieties (Punjab-81, Blue Silver, Bahawalpur-79, and Yecora) yield about the same
under identical management conditions, although one trial ranks them in the order
in which they have just been listed (for our purposes, Punjab-81 and Bahawalpur-79
are considered new varieties).
Yield and planting date-In all three survey areas, farmers plant wheat at dates
which are later than optimal, a practice strongly related to the previous crop in the
rotation and seen most frequently in the cotton-wheat cropping system (Byerlee et
al. 1986). Thus, not only yield performance per se but also yield performance at late
planting dates may affect farmers' choice of varieties.
Plant breeders usually try to develop early maturing varieties for circumstances in
which the growing season is curtailed. Among the varieties listed earlier, Blue Silver
and Bahawalpur-79 are short season releases recommended for late planting. The
new variety Faisalabad-83, not widely grown, and the old rust susceptible variety
SA-42, common in Mardan, are also short season varieties.
Table 6.4. Farmers' reasons for planting both old and new wheat varieties
Percentage of farmers
Rice zone Cotton zone Mardanb
Compare performance 35 57 43
Different variety for late planting 14 17 43
Seed multiplication 19 7
Different variety for home consumption 14 3
Risk aversion 3 13
Other 16 3 14
a Some farmers offered more than one reason; the most prominent is recorded here.
b Only 14 farmers in Mardan planted both old and new varieties.
8 WL-711 is an intermediate maturity variety, one of the reasons it has fit so well into
the cropping system in the cotton-wheat zone, but for simplicity it will be analyzed
with the full season varieties.
A second approach taken by researchers to the constraint of late planting,
particularly in areas where heat stress is a problem, is to plant a variety late and
evaluate its performance regardless of whether it is supposed to be an early,
intermediate, or late maturing variety. Under this criterion, at late planting dates
Pak-81, a relatively long season variety, continues to perform very well with respect
to the short season varieties Blue Silver and Bahawalpur-79; WL-711 also may
perform somewhat better. Punjab-81 does well at late planting, but the yields of old
varieties Sandal and Yecora decline greatly when they are planted late (Hobbs 1985;
Crop rotation and variety-Crop rotation and varietal characteristics combine to
influence farmers' varietal choices in different ways in the three survey areas. In the
cotton zone, where late planting is common, both normal season and short season
varieties were planted late (Figure 6.1). Larger farmers in all three zones were
more likely to plant more than one variety. In the cotton zone, however, farm size did
not vary between farmers planting a short season variety and those who did not. All
varieties chosen, whether by the larger farmers who tended to plant more than one
variety or the smaller farmers who planted only one, had to perform relatively well
at late planting.
In the rice zone somewhat less wheat is planted late, although planting dates vary
more from year to year than they do in the cotton zone. Figure 6.1 shows that, in
contrast to the cotton zone, in the rice zone short season varieties were usually
planted later than full season varieties. Furthermore, farmers planting short season
varieties tended to have more land than farmers who did not. These factors suggest
that farmers in the rice zone often choose full season varieties for earlier planting
and early maturing varieties for later planting. (Their choice probably relates to the
fact that Yecora, once the dominant variety in the rice zone, suffers heavy yield
losses at late planting.) Also, larger farmers in the rice zone may have a wider range
of wheat planting dates than do smaller farmers, and thus be more likely to switch
to an early variety at the later dates.
Mardan presents a different picture of farmers' choices of variety and planting date.
In the sample analyzed here, late planting was less common than in either the cotton
or the rice zone (Figure 6.1). As in the rice zone, early maturing varieties were
usually planted after full season varieties. But compared with farmers in the rice
zone, farmers in Mardan who planted early maturing varieties (notably the old
variety SA-42) tended to have less land than farmers planting only full season
varieties. As in the other two zones, larger farmers in Mardan were more likely to
diversify across varieties, but they were more likely to diversify across two or more
full season varieties.
Straw yield-Another factor that may influence varietal choice, particularly for
small farmers, is straw yield. Straw yield (or perceived straw yield) was probably a
greater consideration when long strawed varieties were first replaced by shorter
strawed, HYVs at the start of the Green Revolution. In changing from one semidwarf
Oct Nov Dec Jan
Week of planting
Mardan 20 -
I I I I I I I I
4 1 2 3 4 1 2 3 4
Oct Nov Dec
Week of planting
1 2 3 4
3 4 1 2 3 4 1 2 3 4 1 2 3 4
Oct Nov Dec Jan
Week of planting
Figure 6.1. Cumulative dates of planting by wheat varietal group in
rice zone, cotton zone, and Mardan, Pakistan.
variety to another, straw yield is probably less significant, although it may be more
important in Mardan than in Punjab, as fodder prices tend to be higher in NWFP."
However, it is hypothesized that harvest indices between one HYV and another are
similar enough to imply that a strong positive correlation usually exists between
straw yield and grain yield.
Seed shrivelling-An independent assessment of shrivelling characteristics of wheat
varieties is not readily available. A variety's shrivelling characteristics are probably
related to its performance when it is planted late. There was not much evidence from
the survey, however, that farmers' evaluation of shrivelling characteristics was
significantly related to their judgement of how a variety performed when it was
Seed shattering-Data on important commercial varieties' susceptibility to
shattering are not readily available. However, Punjab-81 has been found to be
relatively susceptible, both in trials designed to evaluate this trait (Chaudhry et al.
1985) and in farmers' experience.
Baking quality-Although baking quality can be evaluated by such objective
measures as gluten strength, in this study it was treated essentially as a subjective
judgement and is discussed in the next section.
Subjective varietal characteristics-Farmers in the survey who were either
planting new varieties or knew about them were asked to compare characteristics of
a specific old variety that they had planted or were planting with those of a specific
new variety they were planting or knew about. For each characteristic, farmers were
asked whether they thought the new variety was better, the old variety was better,
or both varieties were the same. "Don't know" responses were also recorded.
In the rice zone, responses of farmers already planting new varieties differed
significantly from the responses of farmers who had only heard of new varieties, for
all characteristics. As expected, farmers with no direct experience of new varieties
were more likely not to have an opinion. Also as expected, a larger proportion of
farmers planting new varieties evaluated them favorably. Their positive opinions
were strongest for grain and straw yield, intermediate for late planting performance
and shrivelling, and weakest for shattering resistance and chapati (baking) quality.
9 In fact, though grain-to-straw ratios are higher for HYVs than for the varieties they
replaced, greater biomass production may still lead to higher straw production from
fields sown to semidwarfs. Nonetheless, perceptions are important: Husain (1987)
demonstrates that even today, in mountainous areas of northern Pakistan, farmers
believe the traditional varieties produce more straw than the HYVs although objective
yield cuts show per hectare straw production to be about equal. Straw quality may
also be an issue.
In fact, farmers planting new varieties, as well as farmers who were not, were more
likely to say that the old variety had more shattering resistance and made better
chapatis. This response was particularly striking for chapati quality (Table 6.5).
These evaluations are probably related to the relatively greater use of Punjab-81
(which is particularly subject to shattering) in the rice-wheat zone, and a preference
for Yecora for quality.
In the cotton zone, differences between nonadopters and adopters were also
significant for all characteristics. Even more than in the rice zone, farmers who had
only heard of new varieties were less likely than farmers who had adopted them to
voice an opinion about their characteristics. For all characteristics, adopters were
more likely to rate the new variety more favorably and nonadopters to rate the old
one more favorably. Adopters were most likely to give favorable ratings for late
planting performance and general yield performance; they gave the lowest ratings for
shattering and shrivelling characteristics (Table 6.6).
In Mardan, differences between adopters and nonadopters were significant only for
opinions on yield. Adopters overwhelmingly favored their new variety and
nonadopters were more likely to support the old one. Although the differences among
Table 6.5. Farmers' perceptions of wheat varietal characteristics, rice zone
Percentage of farmers
New Old Same Don't know
Which variety ...
Yields more? P" 74 12 12 2
Ka 33 17 28 22
Provides more straw? P 77 18 4 2
K 39 22 17 22
Makes better chapatis? P 21 72 7 0
K 11 50 11 28
Is better for late planting? P 51 23 18 9
K 11 39 17 33
Shatters less? P 35 40 21 4
K 6 33 11 50
Shrivels less? P 48 16 16 20
K 11 17 17 56
a Row "P" refers to farmers who plant new varieties. Row "K" refers to farmers who
know about new varieties but do not plant them.
______ lU :