Front Cover
 Title Page
 Table of Contents
 New wheats for a secure, sustainable...
 Agriculture : an agent for...
 Prerequisites for sustainable...
 Breeding wheats for lasting food...
 Options for increasing yield...
 Protecting yield potential
 Moving beyond yields in marginal...
 Improvements in wheat quality
 Biotechnology and wheat improv...
 Crop and natural resource management...
 Information management tools for...
 Back Cover

Title: New wheats for a secure, sustainable future
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00077507/00001
 Material Information
Title: New wheats for a secure, sustainable future
Physical Description: iv, 28 p. : ill. ; 26 cm.
Language: English
Creator: Reeves, Timothy G
International Maize and Wheat Improvement Center
Publisher: CIMMYT
Place of Publication: Mexico D.F
Publication Date: c1999
Subject: Wheat -- Varieties -- Research   ( lcsh )
Wheat -- Breeding -- Research   ( lcsh )
Sustainable agriculture   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 27-28).
Statement of Responsibility: Timothy G. Reeves ... et al..
Funding: Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
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Bibliographic ID: UF00077507
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 43931387
isbn - 9706480404


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Table of Contents
    Front Cover
        Front cover
        Inside front cover
    Title Page
        Page i
        Page ii
    Table of Contents
        Page iii
        Page iv
    New wheats for a secure, sustainable future
        Page 1
    Agriculture : an agent for change
        Page 2
    Prerequisites for sustainable agriculture
        Page 3
    Breeding wheats for lasting food security
        Page 4
    Options for increasing yield potential
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Protecting yield potential
        Page 9
        Page 10
    Moving beyond yields in marginal environments
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
    Improvements in wheat quality
        Page 16
    Biotechnology and wheat improvement
        Page 17
    Crop and natural resource management research
        Page 18
        Page 19
        Page 20
    Information management tools for sustainable systems
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    Back Cover
        Page 29
Full Text


New Wheats

for a Secure,

Sustainable Future

Timothy G. Reeves, Sanjaya Rajaram,
Maarten van Ginkel, Richard Trethowan,
Hans-Joachim Braun, and Kelly Cassaday

Maarten van Ginkel, head of bread wheat
breeding at CIMMYT, holds one of the
large-spiked wheats (right) that promise
to raise yields in wheats. On the left he
holds a normal wheat spike. (See page 7.)



New Wheats for

a Secure, Sustainable


Timothy G. Reeves, Sanjaya Rajaram, Maarten van Ginkel,
Richard Trethowan, Hans Joachim Braun, and Kelly Cassaday*

* All authors are staff of CIMMYT. T.G. Reeves is Director General; S. Rajaram is Director
of the Wheat Program; M. van Ginkel is Head, Bread Wheat Breeding; Richard
Trethowan is a Wheat Breeder; H.-J. Braun is a Wheat Breeder (based in Turkey); and
Kelly Cassaday is a Writer/Editor. An earlier version of this paper was presented at the
9h Wheat Breeding Assembly, 27 September 1 October, 1999, University of Southern
Queensland, Toowoomba, Queensland, Australia.

CIMMYT (www.cimmyt.mx or www.cimmyt.cgiar.org) is an internationally funded, nonprofit
scientific research and training organization. Headquartered in Mexico, the Center works with
agricultural research institutions worldwide to improve the productivity, profitability and
sustainability of maize and wheat systems for poor farmers in developing countries. It is one of 16
similar centers supported by the Consultative Group on International Agricultural Research
(CGIAR). The CGIAR comprises about 60 partner countries, international and regional
organizations, and private foundations. It is co-sponsored by the Food and Agriculture
Organization (FAO) of the United Nations, the International Bank for Reconstruction and
Development (World Bank), the United Nations Development Programme (UNDP), and the United
Nations Environment Programme (UNEP). Financial support for CIMMYT's research agenda also
comes from many other sources, including foundations, development banks, and public and private

F U T U R E CIMMYT supports Future Harvest, a public awareness campaign that builds
HAR EST understanding about the importance of agricultural issues and international
agricultural research. Future Harvest links respected research institutions, influential public figures,
and leading agricultural scientists to underscore the wider social benefits of improved agriculture
peace, prosperity, environmental renewal, health, and the alleviation of human suffering
(www. futureharvest.org).

o International Maize and Wheat Improvement Center (CIMMYT) 1999. Responsibility for this
publication rests solely with CIMMYT. The designations employed in the presentation of material
in this publication do not imply the expressions of any opinion whatsoever on the part of CIMMYT
or contributory organizations concerning the legal status of any country territory city, or area, or of
its authorities, or concerning the delimitation of its frontiers or boundaries.

Printed in Mexico.

Correct citation: Reeves, T.G., S. Rajaram, M. van Ginkel, R. Trethowan, H-J. Braun, and K.
Cassaday. 1999. New Wheats for a Secure, Sustainable Future. Mexico, D.E: CIMMYT.

Abstract: This paper reviews strategies used by CIMMYT and its partners to develop sustainable
wheat production systems for favored and marginal areas. These strategies aim to achieve an
optimal combination of the best genotypes (G), in the right environments (E), under appropriate
crop management (M), and appropriate to the needs of the people (P) who must implement and
manage them. The first section of the paper presents new options for raising wheat yield potential
and discusses research on disease and stress tolerance, which is aimed at protecting yield potential
in farmers' fields (with special emphasis on drought tolerance). Next, advances in durum wheat
yield potential are reviewed; these advances may prove particularly valuable in marginal
environments. Other wheat research initiatives for marginal environments are described as well.
This is followed by a review of the role of biotechnology in wheat improvement, research on wheat
quality, and initiatives in crop and natural resource management research. The paper concludes
with a summary of the latest data on the global impacts of wheat research and a discussion of
trends that could affect whether and how this impact is maintained.

ISBN: 970-648-040-4

AGROVOC descriptors: Wheats; Triticum; Hard wheat; Winter crops; Spring crops; High yielding
varieties; Hybrids; Plant production; Production policies; Food production; Food security; Plant
breeding; Plant biotechnology; Nutrient improvement; Drought resistance; Pest resistance; Disease
resistance; Crop management; Resource management; Sustainability; Innovation adoption; Yield
increases; On farm research

Additional keywords: CIMMYT; Participatory research
AGRIS category codes: E14 Development Economics and Policies; F30 Plant Genetics and Breeding

Dewey decimal classification: 338.162


iv Acknowledgments
1 New Wheats for a Secure, Sustainable Future
2 Agriculture: An Agent of Change
3 Prerequisites for Sustainable Agriculture
4 Breeding Wheats for Lasting Food Security
4 Options for Increasing Yield Potential
6 Gene pools of winter and spring hexaploid wheats
6 Introgressing spring and winter wheat gene pools
6 Chinese wheats: A wellspring of diversity
6 Hybrid wheats
7 Landraces
7 Improved plant ideotype
7 Phenological traits
7 Physiological traits
8 Synthetic wheats: Delivering diversity to plant breeders
8 Alien substitutions and translocations
9 Protecting Yield Potential: The Role of Resistance to
Pathogens and Pests
11 Moving beyond Marginal Yields in Marginal Environments
11 Breeding for drought tolerance
14 Higher yielding durum wheats
15 Regional research on wheat for marginal environments
16 Improvements in Wheat Quality
17 Biotechnology and Wheat Improvement: An Example of
18 Crop and Natural Resource Management Research
19 Improved input use efficiency
19 Bed planting systems
20 Farmer participatory research
21 Information Management Tools for Sustainable Systems
22 Conclusions
24 A new research paradigm for new research impacts
24 The shape of things to come
27 References


The authors are grateful to many colleagues within CIMMYT who
contributed information for this paper. Special thanks go to staff of
the Wheat Program, as much of their research is described here,
including A. Mujeeb-Kazi, I. Ortiz-Monasterio, J. Pena, W. Pfeiffer,
M.P Reynolds, R.P Singh, K.D. Sayre, and P. Wall. L. Harrington
and J. White of the Natural Resources Group, and A. McNab and
D. Poland of Information Services, also generously provided
information for this paper. We thank the CIMMYT design section
for layout and production of the publication.
None of the work reported here would have been possible
without the continuining support of CIMMYT's investors, the
members of the CGIAR. Amongst those we particularly thank our
core investors.

New Wheats for a Secure,

Sustainable Future

Timothy G. Reeves, Sanjaya Rajaram, Maarten van Ginkel,
Richard Trethowan, Hans-Joachim Braun, and Kelly Cassaday

At the same time that we are
witnessing a proliferation of
agricultural innovations unlike any
seen previously, hunger and poverty
remain the defining conditions of life
for hundreds of millions of people.

New agricultural knowledge and
technologies are announced almost
daily. The shifting alliances and the
achievements of transnational seed
chemical-pharmaceutical companies
are minutely analyzed in the media. It
is easy to forget that this frenetic
activity occurs in a sobering context-a
world of persisting hunger.
Even a small number of facts are
sufficient to demonstrate the gravity of
the world food situation. More than
800 million people in developing
countries-20% of the population
cannot be certain that they will get
enough to eat, because they lack the
resources to grow or purchase
sufficient food. The downward spiral
of hunger and poverty remains serious
in many regions and countries. An
estimated 1.3 billion people live in
households earning US$ 1 per day or
less per person. Asia has 73% of the
world's poor people (World Bank
1997), and as we move into the new
millennium South Asia will continue to
be the home of half of the world's poor.

Though Asia will have the highest
absolute number of poor people, the
number of poor people in Sub
Saharan Africa (which currently has
17% of the world's poor) will grow by
40% between 1990 and 2000, and the
number of undernourished people
will rise by 70% between 1988-90 and
2010 (World Bank 1997; Reeves,
Pinstrup-Anderson, and Pandya
Lorch 1997).

Developing countries are projected
to increase their demand for cereals
by about 80% between 1999 and 2020
(Pinstrup-Andersen and Pandya
Lorch 1997). Rosegrant et al. (1997)
report that over the next two decades
global demand for wheat and maize
could rise by 40% and 47%,
respectively. By 2020, it is expected
that 67% of the world's wheat
consumption and 57% of the world's
maize consumption will occur in
developing countries.

Even if food crop productivity
in developing countries remains at
current levels, by 2020 developing
countries will be importing 138
million tons of wheat and 62
million tons of maize every year. In
these circumstances, how will we
ensure food security for the poorest
of the poor?

Agriculture: An

Agent of Change

The role of more productive, profitable
maize and wheat systems in fostering
food security, generating local
employment, raising local incomes,
and thus alleviating poverty must not
be underestimated. A recent report
(UNDP 1997) emphasizes that
agricultural research is the central
means of achieving those goals:
"About three-quarters of the world's
poorest people live in rural areas,
dependent on agricultural activities
for their livelihoods. For these people,
pro-poor growth means raising
agricultural productivity, efficiency,
and incomes." The report points out
why agriculture can succeed where
other initiatives might fail: "Raising
the productivity of small-scale
agriculture does more than benefit
farmers. It also creates employment on
the farm and off-and reduces food
prices. The poor benefit most, because
about 70% of their consumption is
food, mostly staples, and regular
supplies and stable prices can greatly
reduce the vulnerability of the poor.
Strong support to small-scale
agriculture was at the core of the most
successful cases of poverty
reduction-such as China in 1978-85,
Malaysia since 1971, and India in the
early 1980s."

In these circumstances, the
challenges for research-and the
opportunities to alleviate much
human suffering-are clear. We will
have to develop the innovations that
make it possible for people to benefit
from more efficient, low-cost systems
for food production. These systems

must function without mining the
natural resources on which agriculture
depends. They are needed urgently in
favored as well as less favored
agricultural areas.

In this paper, we review strategies
used by the International Maize and
Wheat Improvement Center
(CIMMYT) and its partners to develop
sustainable wheat1 production
systems for favored and marginal
areas. These strategies aim to achieve
an optimal combination of the best
genotypes (G), in the right
environments (E), under appropriate
crop management (M), and
appropriate to the needs of the people
(P) who must implement and manage
them (Reeves 1998, 1999). Each
variable in this GxExMxP
"sustainability equation" is addressed
in the sections that follow. After further
defining what we mean by
"sustainable technology," we:

* Review new options for raising wheat
yield potential.
* Discuss research on disease and stress
tolerance, which is aimed at
protecting yield potential in farmers
fields. We give special emphasis to
drought tolerance.
* Describe advances in durum wheat
yield potential which may prove
particularly valuable in marginal

1 In this paper we focus on strategies
related to wheat, although CIMMYT's
research mandate encompasses maize as
well. We also give greater attention to
wheat genetic improvement than to
crop and natural resource management
research, but readers should be advised
that CIMMYT engages in a great deal of
crop and resource management
research, for wheat as well as maize. For
a general overview, see our annual
report, CIMMYT in 1998-99: Science to
Sustain People and the Environment.

* Provide an overview of other wheat
research initiatives for marginal
* Review the role of biotechnology in
wheat improvement.
* Describe recent research on wheat
quality. For many poor farmers, an
increase in wheat quality means a
corresponding increase in income.
* Briefly review recent initiatives in
crop and natural resource
management research in wheat.

We conclude by summarizing the
latest data on the global impacts of
our wheat research and by discussing
trends that could affect whether and
how this impact is maintained into
the future.


for Sustainable


To be sustainable, farming systems
must be biologically sensible,
economically viable, environmentally
sound, socially acceptable, and
politically supportable (Reeves 1998,

* Sustainable farming systems must be
biologically sensible. For example,
the choice of crop(s), their
management, and the level of
intensification must be consistent
with the biophysical realities of the
farming system.
* Sustainable farming systems must be
economically viable at the farm and
national levels. Poor farmers cannot

invest in systems that will not
produce reasonable yields and (even
better) cash income, now and in the
future. At the national level, the
reality in most developing countries
is that economic well-being and
development are almost invariably
based on productive and profitable
agriculture, the "engine room" of
subsequent industrialization.
* Sustainable farming systems must
be environmentally sound.
Economic success in agriculture
cannot come at the expense of our
soils, air, water, landscapes, and
indigenous flora and fauna.
* Sustainable farming systems must
be socially acceptable. They must be
appropriate to the people who,
relying on their own meager
resources, are responsible for
implementing and managing them.
The need for socially acceptable
systems implies the need for a better
understanding of farmer and
community needs and values, as
well as better targeting of
technology to meet local conditions.
* Finally, sustainable farming systems
must be politically supportable.
Political support depends largely on
successfully meeting the first three
requirements of sustainability. If
economic growth is catalyzed by
agriculture within an
environmentally sound, socially
acceptable framework, politicians
will continue to view agriculture as
justifying support.

All of these components combine
to form the whole: sustainable
agriculture. If one is neglected, it can
seriously reduce the rate and extent of
progress towards sustainability and
food security.

Breeding Wheats

for Lasting Food


CIMMYT's wheat breeding
methodology is tailored to develop
widely adapted, disease resistant
germplasm with high and stable
yield across a wide range of
environments-favorable as well as
marginal. To focus this work, we
have grouped wheat production
areas in developing countries into 12
"mega-environments." A mega
environment is a broad but not
necessarily contiguous geographical
area, usually international and
frequently transcontinental. Mega
environments are defined in terms of
the type of wheat cultivated (spring,
facultative, or winter wheat), the
amount of water available to the
crop, temperature regime, mineral
toxicity in the soil, and the major
diseases and pests that limit food
CIMMYT wheat breeders, through
collaboration with national wheat
research programs and genebanks,
scour the world for new and different
sources of yield potential and other
traits of interest. We give the utmost
attention to genetic diversity within
CIMMYT germplasm to minimize the
risk of genetic vulnerability, since our
breeding materials are used in research
programs worldwide, and the
numerous varieties developed from
those breeding materials are grown by
hundreds of millions of farmers. We
also believe that the use of genetically
diverse material is mandatory for
future increases in yield potential and
yield stability. At CIMMYT, parental

groups of lines for crossing in any
year consist of 500-800 lines. Twice a
year around 30% of parental stocks
are replaced with outstanding
introductions. In addition, commercial
cultivars from national agricultural
research systems (NARSs) and non
conventional sources (e.g., durum
wheat and alien species) are used to
incorporate desired traits by
recombination or translocation. The
introductions are mostly used as the
female parent to preserve cytoplasmic

Options for

Increasing Yield


Like most wheat improvement
programs, the CIMMYT wheat
improvement program has many
reasons for seeking to raise-and
protect-genetic yield potential. High
yield potential, assessed in breeders'
trials, is positively associated with
superior crop performance in farmers
fields, even in stressed environments.
Another consideration is that most
farmers readily adopt and share
improved wheat seed, even in areas
where problems with infrastructure
and lack of farmer support services
frustrate the adoption of other
agricultural inputs and practices.
Those may be regarded as the
"humanitarian" reasons for seeking
higher yields, but it is important to
remember that there are also
compelling environmental reasons to
break yield barriers. We must be
realistic about changing land use

Breeding Wheats

for Lasting Food


CIMMYT's wheat breeding
methodology is tailored to develop
widely adapted, disease resistant
germplasm with high and stable
yield across a wide range of
environments-favorable as well as
marginal. To focus this work, we
have grouped wheat production
areas in developing countries into 12
"mega-environments." A mega
environment is a broad but not
necessarily contiguous geographical
area, usually international and
frequently transcontinental. Mega
environments are defined in terms of
the type of wheat cultivated (spring,
facultative, or winter wheat), the
amount of water available to the
crop, temperature regime, mineral
toxicity in the soil, and the major
diseases and pests that limit food
CIMMYT wheat breeders, through
collaboration with national wheat
research programs and genebanks,
scour the world for new and different
sources of yield potential and other
traits of interest. We give the utmost
attention to genetic diversity within
CIMMYT germplasm to minimize the
risk of genetic vulnerability, since our
breeding materials are used in research
programs worldwide, and the
numerous varieties developed from
those breeding materials are grown by
hundreds of millions of farmers. We
also believe that the use of genetically
diverse material is mandatory for
future increases in yield potential and
yield stability. At CIMMYT, parental

groups of lines for crossing in any
year consist of 500-800 lines. Twice a
year around 30% of parental stocks
are replaced with outstanding
introductions. In addition, commercial
cultivars from national agricultural
research systems (NARSs) and non
conventional sources (e.g., durum
wheat and alien species) are used to
incorporate desired traits by
recombination or translocation. The
introductions are mostly used as the
female parent to preserve cytoplasmic

Options for

Increasing Yield


Like most wheat improvement
programs, the CIMMYT wheat
improvement program has many
reasons for seeking to raise-and
protect-genetic yield potential. High
yield potential, assessed in breeders'
trials, is positively associated with
superior crop performance in farmers
fields, even in stressed environments.
Another consideration is that most
farmers readily adopt and share
improved wheat seed, even in areas
where problems with infrastructure
and lack of farmer support services
frustrate the adoption of other
agricultural inputs and practices.
Those may be regarded as the
"humanitarian" reasons for seeking
higher yields, but it is important to
remember that there are also
compelling environmental reasons to
break yield barriers. We must be
realistic about changing land use

patterns and their implications for
agriculture. There is limited scope to
open new land for crop production, and
there is an even more urgent need to
protect land (in particular, marginal
land) from inappropriate uses. In recent
decades developing countries have
fortunately relied more on increased
yields than on an expansion of cropped
area to feed their populations. Between
1961 and 1990, yield increases accounted
for 92% of the additional cereal
production in the developing world
(Reeves, Pinstrup-Anderson, and
Pandya-Lorch 1997). When farmers in
stable, high production environments
obtain better yields, the need to intensify
production in fragile agricultural
systems is reduced, offering a much
more sustainable approach to meeting
long-term demand for cereal production
in developing countries.2 Because
higher yielding lines are frequently bred
to use inputs such as nutrients and
water more efficiently, higher yields are
not obtained at a higher cost to the
environment. As our CIMMYT
colleague, Nobel Laureate Norman
Borlaug, has said, "The only way for
agriculture to keep pace with population
and alleviate world hunger is to increase
the intensity of production in those
ecosystems that lend themselves to
sustainable intensification, while
decreasing intensity of production in the
more fragile ecologies" (Borlaug and
Dowswell 1997).

2 For example, if India were suddenly
required to produce its current wheat
harvest using the technologies of 30
years ago, Indian farmers would have to
bring more than 40 million hectares of
additional land into production. The
wheat varieties developed in the past
three decades were instrumental in
preventing damage to areas that are not
well suited to agriculture.

( .I'1il ] %m 'i kum I ll "11 12".. 11
11111 111

1965 i0 75i 80 85 C91 95l
\a letN \eai of release

Figure 1. Grain yield trend for semidwarf bread
wheat lines developed at CIMMYT since 1966,
under conventional planting, average for 1997,
1998, and 1999 crop cycles at CIANO, Cd.
Obreg6n, Mexico.
Source: K.D. Sayre, CIMMYT.

The selection of segregating
populations and consequent yield
testing of advanced lines is paramount
for identifying high yielding, input
responsive wheat genotypes. The
increase in yield potential of CIMMYT
cultivars developed since the 1960s is
shown in Figure 1 (K. Sayre, pers.
comm.). The data do not indicate that
we are approaching a yield plateau,
and the performance of recently
released lines such as Attila and
Baviacora, and of Lrl9-derived Veery,
indicates that yield potential has been
further enhanced.

With yield, a complex trait still
not well understood genetically or
physiologically, the use of proven,
high yielding sources, as well as
genetically diverse germplasm, will
continue to be paramount for
increasing yield potential. Genetic
diversity and the opportunity for its
recombination through crossing will
be important to break undesired
linkages and increase the frequency

of desirable alleles. Future
breakthroughs in yield potential are
likely to come from such genetically
diverse crosses. Examples are given
below, along with a description of
other efforts to raise both spring and
winter wheat yield potential.

Gene Pools of Winter and
Spring Hexaploid Wheats
The variability currently available
among spring and winter hexaploid
wheats is still extensive. New high
yielding sources from within the
CIMMYT Bread Wheat Program and
from around the world are identified
and intercrossed. For example, high
yielding spring wheat lines from South
Asia and China are regularly
intercrossed with the highest yielding
lines identified in Mexico, followed by
selection for types superior to either
parent, carrying all desirable genes.
Likewise elite winter wheats are
intercrossed. Considerable progress
can still be made in this way as yield is
controlled by many genes and the
optimal combinations of these genes
for any particular environment may
not yet have been realized.

Introgressing Spring and
Winter Wheat Gene Pools
By introgressing genetic variability
from winter wheats, breeders have
considerably augmented the yield
potential of spring wheats. The Veery
wheats, developed from crosses of
CIMMYT spring wheats and Russian
winter wheat, represented a quantum
leap in spring wheat yield and wide
adaptation during the 1970s and 1980s
(CIMMYT 1986) (their contribution to
drought tolerance is discussed later).
More recently, the spring bread wheat

Attila, developed from crosses with
western European and US winter
wheats, has rapidly gained ground on
the Indian subcontinent. New evidence
indicates that yield potential in winter
wheat may also benefit from crosses
with high yielding spring wheats.

Chinese Wheats: A
Wellspring of Diversity
Before the mid-1980s, only a limited
amount of wheat germplasm from
outside China was available to
Chinese breeders. Since the mid
1980s, CIMMYT and Chinese
scientists have worked together to
benefit from the diversity in each
others' wheat germplasm. More
than 100 Chinese varieties contain
CIMMYT germplasm, and up to
20% of new CIMMYT spring wheats
have Chinese wheats in their
pedigrees. Apart from its resistance
to biotic pests such as scab and
Karnal bunt, modern Chinese
germplasm offers new alternatives
for raising the yield potential of
wheat; yields of elite Chinese
wheats in China can exceed 10 t/ha.

Hybrid Wheats
The expression of heterosis for yield in
wheat can be high. Although it has
been well documented, heterosis has
not been exploited commercially to
any great extent. Hybrids offer the
unique opportunity of combining
different gene pools in the production
of the Fl hybrid. Because heterosis is,
to some extent, a function of genetic
distance, CIMMYT is well positioned
to exploit this need for genetic
diversity. During the past three years,
CIMMYT hybrids have produced
yields that are 15-20% higher than
those of commercially grown cultivars

in Mexico, and levels of heterosis of
a similar maximum size have been
reported. The difficulty of producing
Fl seed in a cost-effective way
remains the greatest limitation to the
exploitation of such hybrids, but
CIMMYT breeders expect to resolve
this issue by introgressing
outcrossing traits.

Many high yielding CIMMYT
wheats have a considerable number
of landraces in their pedigrees. A
coefficient of parentage analysis
reveals that on average CIMMYT
advanced lines contain as many as
50 landraces in their genetic history.
Breeding programs have still not
exploited all of the yield-controlling
genes available in landraces.
Landraces may also provide novel
sources of adaptation, which will
allow breeders to select more stable,
high yielding lines. As yields
increase, consumer preferences will
also turn to increased quality and
taste. Here, locally preferred
landraces can play a very new and
exciting role.

Improved Plant Ideotype
CIMMYT breeders are using
increased knowledge of the
physiological bases of yield to define
a range of optimal wheat plant
ideotypes. We are examining plants
with large spikes, which contain
many grains per spikelet (see photo,
inside front cover). The optimization
of source-sink relationships is also
being examined with a view to
obtaining a better balance of grain
filling characters. The hexaploid
wheat and other gene pools are
being searched for examples of

extreme expression of these
characters. We believe advances of
yield potential on the order of at least
20% in optimum conditions can still
be realized by fine-tuning the source
sink relationships in wheat.

Phenological Traits
By manipulating photoperiod and
vernalization genes, we are
attempting to tailor genotypes to
specific environments. Photoperiod
and vernalization genes optimize the
timing and duration of flowering and
grain-filling, thereby influencing the
wheat plant's eventual yield. New
and different sources of these genes
are being exploited through the use of
high-latitude germplasm from Central
Asia and Canada.

Physiological Traits
A strong body of evidence now
indicates that physiological traits may
complement early-generation
phenotypic selection in wheat. Genetic
progress in increasing yield potential
is closely associated with increased
photosynthetic activity (Rees et al.
1993). Photosynthetic activity as well
as yield potential have increased over
the past 30 years by some 25%. These
findings may have major implications
for CIMMYT's future selection
strategy, since there is evidence that
wheat genotypes with higher
photosynthesis rates have lower
canopy temperatures, a characteristic
that can be measured easily, quickly,
and cheaply. Canopy temperature
depression (CTD) is the cooling effect
exhibited by a leaf as transpiration
occurs. Canopy temperature
depression and stomatal conductance,
measured on sunny days during grain
filling, have shown a strong

association with yields of semidwarf
wheats grown under irrigation, in both
temperate (Fischer et al. 1998) and
subtropical environments (Reynolds et
al. 1994). In addition, CTD measured
on large numbers of advanced
breeding lines in irrigated yield trials
was a powerful predictor of
performance, not only at the selection
site but also for yield averaged across
15 international sites. Canopy
temperature depression has been
shown to be associated with yield
differences between homozygous lines
in warm environments, indicating a
potential for genetic yield gains under
conditions of heat in response to
selection for CTD (Reynolds at al.
1998). Breeders have found CTD to be
highly correlated with yield under
heat conditions among elite lines (van
Ginkel and Trethowan, unpublished),
and the technique may be particularly
useful for more efficiently selecting
wheat genotypes adapted to
environments where heat is a
production constraint.

Synthetic Wheats:
Delivering Diversity to
Plant Breeders
Synthetic wheats are the result of a
cross between two relatives of putative
progenitors of wheat, Triticum
turgidum and T. tauschii, with
subsequent chromosome doubling.
Historically (10,000 to 8,000 years ago),
this cross has probably occurred on
only a few occasions. As a result, the
genetic resources of these two species
have been sampled in only a limited
way in the development of bread
wheat. CIMMYT holds a large number
of T. tauschii accessions from which

many new synthetic hexaploid
wheats have been made (about 650 to
date). These synthetics possess a
range of positive traits, including
resistance to such diseases as Karnal
bunt, fusarium head scab, and
helminthosporium leaf blotch, and
tolerance to heat, drought,
waterlogging, and late frost at
flowering. They are spring types that
are highly crossable to advanced
bread wheats, which means that they
may be used easily in breeding
programs. Through this approach,
CIMMYT breeders have not only
been able to take advantage of the
new variation from T. tauschii, but
have also found a new way to
introgress traits from elite durum
wheats into bread wheat. Synthetics
or their derivatives may also prove
useful in the production of hybrid
wheat and the improvement of bread
wheat quality.

Alien Substitutions
and Translocations
The 1B/lR translocation (discussed
also in the section on drought
tolerance) led to a revolution in the
broad adaptation of wheat. This
translocation from rye increased
wheat biomass, harvest index, and
especially-wide adaptation, which
spurred improvements in wheat yield
in most spring wheat environments.
More recently, a translocated segment
from Agropyron sp. containing the leaf
rust resistance gene Lrl9 has been
linked with a 5-10% increase in yield
in adapted backgrounds. Other alien
sources of higher yield are also
currently under evaluation.


Yield Potential:

The Role of

Resistance to

Pathogens and Pests

Over the past few decades, the gains
from breeding for disease resistance
are likely to have been at least as
important as the gains from breeding
for increased yield potential (Byerlee
and Moya 1993). A recent survey of
wheat breeders in developing
countries indicated that among the
types of materials used in crossing
(including the breeder's own advanced
lines, advanced lines obtained from
other countries, wild relatives, and
landraces), materials from CIMMYT
international nurseries are the most
frequently crossed in pursuit of disease
resistance goals (Rejesus, van Ginkel,
and Smale 1996).

CIMMYT's global effort to breed
wheats with diverse and durable
resistance will protect global food
security by reducing the incidence of
disease epidemics. It will also protect
the environment and farmers' incomes,
by reducing dependence on pesticides
for disease and pest control. In
CIMMYT's target mega-environments,
important fungal diseases of wheat
caused by obligate parasites include
the rusts (one or more of which are the
most economically important diseases
in most wheat production
environments), powdery mildew, and
the bunts and smuts. Widespread

diseases caused by facultative fungal
parasites include septoria tritici blotch,
septoria nodorum blotch, spot blotch,
tan spot, head scab, and a suite of root

The obligate parasites are highly
specialized, and significant variation
exists in the pathogen population for
virulence to specific resistance genes.
The evolution of new virulence (races)
through migration, mutation, and
recombination of existing virulences
and their selection is more frequent in
rust and powdery mildew fungi. For
this reason, these diseases have
required constant vigilance and
attention from breeders. Physiological
races are also known to occur for most
bunts and smuts, although evolution
and selection of new races is less
frequent. Because most bunts and
smuts are easily controlled by chemical
seed treatment, little effort is currently
placed on breeding for resistance,
except for resistance to Karnal bunt.
Successful changes in pathogen races
are even less frequent in the facultative
parasites mentioned earlier.
Since wheat cultivars derived from
CIMMYT germplasm are grown over a
large area and are exposed to a variety
of pathogens under conditions that
may favor disease development, our
strategy has been to utilize resistance
sources that are as diverse as possible
and have shown durability. Genetic
diversity and durability of resistance
against diseases caused by pathogens
such as the rust pathogens are vital for
long-term food security. Resistances
caused by race-specific genes become
ineffective in a short time (in five years
on average at the global level and in
three years for leaf rust, Puccinia
recondita, in Mexico). In contrast,

cultivars with durable resistance have
shown stable resistance for over 50
years at the global level. Consider the
resistance to stem rust (P graminis).
McFadden in the US transferred the
Sr2 gene complex from a tetraploid
emmer wheat to hexaploid bread
wheat in the 1920s (McFadden 1930).
Borlaug in Mexico used this source of
resistance in his breeding program in
the 1940s, and since then this gene, in
concert with several known and
unknown major and minor genes, has
formed the basis of durable resistance
to stem rust in CIMMYT wheat

Following the lesson learnt from
stem rust research, CIMMYT's wheat
breeding in the last three decades has
focused on utilizing diverse sources of
slow rusting resistance to P. recondita
and yellow rust (P striiformis). Genetic
analyses of durable resistance indicate
that effective disease control can be
achieved by combining from three to
five minor, slow rusting genes in a
single cultivar. Such resistance is
expected to provide sufficient
protection to farmers' crop against all
biotypes over a long period. Currently
we are also attempting to identify
molecular markers for each of the slow
rusting genes present in CIMMYT
wheats. If this strategy is successful,
breeding programs will be able to
incorporate known combinations of
minor genes, develop a global strategy
for their deployment, and at the same
time enhance genetic diversity in
farmers' fields.

Recent analysis of trials conducted
in northwestern Mexico confirms that
progress in protecting yield potential
through genetic resistance to leaf rust
is about three times as great as
advances in yield potential itself (R.P.
Singh and K.D. Sayre, pers. comm.).
The economic benefits of CIMMYT's
strategy of incorporating non-specific,
durable resistance to leaf rust into
modern bread wheats have been
estimated using data on resistance
genes identified in cultivars, trial data,
and area sown to cultivars in
northwestern Mexico. Even under the
most conservative scenario, the gross
benefits generated in this region on
about 120,000 ha of wheat from 1970 to
1990 were US$ 17 million (in 1994 real
terms) (Smale et al. 1998). At the global
level, where a considerable area is
sown to cultivars carrying non-specific
resistance, the benefits must be
correspondingly large.

Resistance to the diseases caused
by facultative parasites, such as
Septoria tritici and Fusarium
graminearum, also involves genes that
have additive effects. Tremendous
progress has been made at CIMMYT in
developing semidwarf wheats that
have adequate resistance to Septoria
tritici. Sources contributing to
resistance include wheats from France,
Brazil, China, and Russia. More
recently we have identified synthetic
wheats (T turgidum x T tauschii)
possessing good resistance to septoria
tritici blotch. This new genetic
diversity is currently being transferred
to CIMMYT wheats.

Moving beyond

Marginal Yields in



Limited water availability is probably
the most common stress that affects
farmers in marginal environments, but
they also have to contend with factors
such as diseases, acid soils, extreme
cold and heat, waterlogging, and
mineral deficiencies and toxicities. A
region is defined as marginal when
wheat production drops to 70% of
optimal yield levels, as in, for example,
the highland areas from Turkey to
Afghanistan, the dryland areas of West
Asia and North Africa (WANA), much
of Ethiopia, and the dryland areas of
central and southern India (Table 1).3

Our discussion of CIMMYT's
research directed at marginal areas
begins with a review of the methods
used in breeding drought tolerant
wheats. Next, we describe
achievements in durum wheat
breeding, given the considerable
amount of durum wheat grown in
marginal areas. We conclude with an
overview of specific research
initiatives in regions where marginal
environments present a series of
challenges to wheat production. As the
following sections indicate, CIMMYT

3 Note that, although improved varieties
have a role to play in these areas,
considerable gains will also result from
improved crop and resource management,
especially measures to conserve and
utilize moisture more efficiently in rainfed
areas. Some of these practices are
discussed later in this publication.

Table I Poitions of \\ Ieat piodiuc.ing regions of
tie \\ol Ild that ame defined as iai .giinal

Total liiea Peni:eii
Reion lea I1. lli illu 1ii.al

h 11 .11.1 1, 1
T". 1 I .ll. III. I .'IIIII
.. l II. I I 1. I ll. 1 1 .l I '- III
il I i I I I.I ,,, I l l. II ill I I 11111

SI I I I I. I 1. I I II I
,,, llI,, 1 II I I ,, I ', l h ,,-O II, I Ill

I. h,, 1llhI llhI .11, I 'IIII
Total I 19.3a:I

researchers and their collaborators
are implementing a combination of
strategies to ensure that farmers in
marginal areas are no longer destined
to obtain marginal yields.

Breeding for Drought
The annual gain in genetic yield
potential in drought environments is
only about half (0.3-0.5%) of that
obtained in irrigated, optimum
conditions. Many investigators have
attempted to produce wheat adapted
to semiarid environments but with
limited success. The CIMMYT Wheat
Program follows a system of
breeding for drought tolerance in
which yield responsiveness is
combined with adaptation to drought
conditions. Because most semiarid
environments differ significantly in
annual precipitation distribution, and
because water availability also differs
across years in these environments, it
is prudent to construct a genetic
system in which plant responsiveness
provides a bonus whenever higher
rainfall improves the production
environment. With such a system,

improved moisture is immediately
translated into greater yield gains for

Why do we believe that this can be
done? One compelling piece of
evidence comes in the form of Veery S,
which combines high yield
performance in favorable environments
and adaptation to drought in more
marginal areas. When Veery S was
tested in 73 environments in the early
1980s, its performance differed from
that of other high yielding varieties. It
yielded better than other cultivars not
only in high yielding environments but
also under reduced irrigation (Table 2).
What made this line different was that
it carried the 1B/1R translocation from
rye. By 1990, 63% of the dryland wheat
area in developing countries was sown

to semidwarf wheats (Byerlee and Moya
1993). Many of these wheats possessed
the 1B/1R translocation, which had
been incorporated into hundreds of
genetically different backgrounds and
made available to breeders throughout
the world.

We have conducted several
experiments to compare the
performance of the newest and most
widely adapted wheat germplasm to the
performance of commercial cultivars
from countries in three marginal, low
rainfall mega-environments, under
conditions simulating those
environments (Calhoun et al. 1994; van
Ginkel et al. 1998; Tables 3 and 4). The
most widely adapted CIMMYT lines
yielded better than the commercial
cultivars in all of the simulated
environments. Recent adoption of

Table 2. Effect of the 1BL/1RS translocation on yield characteristics of 28 random F2-
derived F6 lines from the cross Nacozari/Seri 82 under reduced irrigation



Grain yield (kg/ha)
Above-ground biomass at maturity (t/ha)
1,000-grain weight (g)


Source: Villareal et al. (1995).
Note: NS = not significant; = significant at the 0.05 level.

Table 3. Wheat genotypes representing adaptation to different moisture environments

Mega-environment (ME)

ME1 (Irrigated environment)
ME4A (Mediterranean Region)
ME4B (Southern Cone, S. America)

ME4C (South Asian Subcontinent)


Super Kauz, Pavon 76, Genaro 81, Opata 85
Almansor, Nesser, Sitta, Siete Cerros
Cruz Alta, Prointa Don Alberto, LAP1376,
C306, Sonalika, Punjab 81, Barani

Source: Calhoun et al. (1994).

1B difference


152 NS
0.5 *

Table I Glaii \ fields lkg Iial of selected I\\ eat ge)iiot pes grouped bI\ adaptajuon anld
tested uiidei nioisitue ieginies ii1 the \aiqui \alle\ NMeico 1989 911 ai(d 19911 91

-Alaptatjion giotip

I [ i ilI -I I "i i i I. Ii ii- I ll I

I N ,li linIll n I i Iii, I, III.
I ., ,.I I I I ." i I l l .ill l.. II II 1. i i1

Full Late Eail Residutal
iii igation lioiiglit', dcouglitg ioiistue'ie


I I.-.

I.-, I '.



;II. '

1l ..- 1 1. 1 I I II 1- 111 I r 11 1[ k -1 1 '. Il II I I- 11. II. 11- '1 uI I I 11 .1
.1 11 I III I I ,' I I I II I I
SIi ', .1 kI '- 1i I 11i,. .1- 1
* i'.,,i'. I I i ii II ._ll l Ii .I. .Iilll Ii l .iI Il i Il I. ,I

CIMMYT germplasm in those
environments supports the model of
combining input efficiency and input

Another piece of evidence is
Nesser, an advanced line with
superior performance in drought
conditions. Nesser was bred at
CIMMYT-Mexico and identified by
the CIMMYT Mediterranean program
located at the International Center for
Agricultural Research in the Dry
Areas (ICARDA) in Syria. The cross
combines the high yielding CIMMYT
variety Jupateco 75 and the drought
tolerant Australian variety W3918A.
The performance of Nesser in the
dryland environments of WANA has
been widely publicized (ICARDA
1993), and the line is considered to
represent a uniquely drought-tolerant
genotype. This line was selected at
CIMMYT/Mexico under favorable
conditions, and it carries a
combination of input efficiency and
high yield responsiveness. In the
absence of rust, its performance is
quite similar to that of Veery S.

A breeding scheme to achieve the
combination of yield responsiveness
and drought tolerance in wheat is
presented in Table 5. This method is
supported by research on wheat as
well as other crops, in which testing
and selecting in a range of
environments, including well-irrigated
ones, has identified superior
genotypes for stressed conditions (see,
for example, Ehdaie, Waines, and Hall
1988; Duvick 1990, 1992; Bramel-Cox
et al. 1991; Uddin, Carver, and Clutter
1992; Zavala Garcia et al. 1992; and
Cooper, Byth, and Woodruff 1994). The
approach results in the selection of
germplasm that is adopted by farmers
because it translates improved
environmental conditions into yield
gains. The traditional methodology of
selecting only under drought
conditions and narrowly relying on
landrace genotypes does not move
yield levels significantly beyond those
usually obtained, and it does not
provide the farmer with a bonus in
years when rainfall is higher.

Table 5. Methodology for breeding drought-tolerant wheat that is also responsive to
favorable environmental conditions


Higher Yielding
Durum Wheats
Although durum wheat is not cultivated
as widely as bread wheat, it occupies a
special niche in the developing world.
Durum wheat is generally sown in
marginal environments subject to great
climatic fluctuations during the growing
season. The durum crop may experience
heat and drought at different times
during its growth cycle. Most of the
developing world durum area is
concentrated in the countries of WANA,
but durum is also grown in central and
south India,4 Ethiopia, Mexico,
Argentina, Peru, Kazakhstan,

Azerbaijan, and Ukraine. Often the
crop is grown by poor people who rely
on it for a high proportion of calories
in the diet or for income-as durum in
some areas fetches a premium in the
local market.

Short-cycle, semidwarf durum
wheat varieties recently tested in
northwestern Mexico produced a
remarkable 89 kg of grain per hectare
per day, for a final tally of 11.7 t/ha at
harvest (W. Pfeiffer, pers. comm.). This

4 In parts of India, durum production is
relegated to the hottest and driest

Crosses involving widely adapted germplasm, representing yield
potential, yield stability, and input responsiveness, with lines carrying
proven drought tolerance in the setting of the respective drought mega
environments (ME4A, ME4B, or ME4C), and input (water) use efficiency.
Winter wheat and synthetics are emphasized.
Individual plants are raised under irrigated and optimally fertilized
conditions, and inoculated with a wide spectrum of rust virulence. Only
robust and horizontally resistant plants are selected. These plants may
represent adaptation and responsiveness to favorable environmental
The selected F2 plants are evaluated as F3s in a modified pedigree/bulk
breeding system (Rajaram and van Ginkel 1995) under rainfed conditions
or very low water availability. The selection is based on such criteria as
spike density, biomass/vigor, and grains/m2, among others (van Ginkel
et al. 1998). This index helps identify lines that may adapt to conditions in
which water is limited (that is, lines that are input efficient).
Selected lines from F3 are further evaluated under optimum conditions,
as for the F2.
As F3.
As F4.
Simultaneous evaluations under low and intermediate (representing the
higher rainfall years in marginal drought environments) water regimes.
Selection of those lines showing outstanding performance under both
conditions. Further evaluation in international environments is carried
out for verification.

is an increase of more than 20% over
the previous generation of durum
wheats. Generally average yields of
durum wheat in farmers' fields in
northwestern Mexico are 6 t/ha, and
the world average is 2-3 t/ha. If these
recently tested wheats retain some of
their yield advantage in marginal
conditions, they may prove to be a
valuable asset for breeding programs.

Regional Research
on Wheat for Marginal
West Asia and North Africa. About
one-third of the area planted to wheat
in the developing world is located in
marginal environments plagued by
drought and soil problems. These
problems are frequently exacerbated
by a lack of infrastructure and farmer
support services. Most of the world's
drought-prone wheat area is
concentrated in the WANA region
(Table 1). Wheat is the principal food
source for people in WANA, who on
average consume more than 145 kg/
cap/yr, one of the highest levels of per
capital consumption in the world.

CIMMYT efforts aimed at
improving wheat production in
WANA are conducted in conjunction
ICARDA Joint Dryland Wheat
Program for West Asia and North
Africa seeks to increase wheat
productivity by developing spring
bread and durum wheats that are
better adapted to the WANA region.
Wheats developed or identified by the
program are widely adapted and
possess enhanced disease and insect
resistance, as well as better tolerance to
the prevalent abiotic stresses. This is
why our partners in the region
increasingly select them for use in their

own breeding programs. Farmer
adoption of CIMMYT and CIMMYT/
ICARDA-derived varieties in WANA
continues to increase, with more than
90 wheat varieties released in 21
countries in the region over the past 10

International Winter Wheat
Improvement Program (IWWIP) based
in Ankara, Turkey, came into existence
11 years ago with the purpose of
generating winter wheats for
developing countries, particularly in
the WANA region. Over the past two
years, IWWIP has expanded its
collaboration with winter wheat
programs in the developing world.
New research partnerships with
colleagues from Central Asia and the
Caucasus have greatly increased the
number of cooperators.

The program is devoting particular
attention to improving resistance to
yellow rust, which is the most serious
winter wheat disease in WANA. It
conducts trials using artificial
inoculation in Ankara, Konya, and
Eskisehir (Turkey), Aleppo (Syria), and
Iran. It is also conducting research on
micronutrients aimed at identifying
zinc-efficient wheats to be used in
crosses and alien materials that may be
potential sources of zinc efficiency. At
present, rye and triticale seem to be the
best sources, but other alien species are
also being tested at Turkey's Qukurova

Central Asia and the Caucasus. The
republics of Central Asia and the
Caucasus are relatively diverse in
climate, agricultural production, and
population. What these eight countries
(Armenia, Azerbaijan, Georgia,
Kazakhstan, Kyrgyzstan, Tadjikistan,
Turkmenistan, and Uzbekistan) have in

common is that they are all in transition
from being centrally planned economies
to becoming market-oriented ones.
Nearly 15 million hectares are planted
to wheat in the region, but with the
exception of Kazakhstan, all countries
have to import wheat to satisfy
domestic demand. A major objective of
their governments is to become self
sufficient in wheat.

In 1992, after the political situation
changed, CIMMYT re-established
contacts with research programs in the
region. In 1998, CIMMYT was
mandated by the CGIAR to address the
needs for wheat germplasm in this
region. Breeders and research
administrators from the region have
visited IWWIP in Ankara or CIMMYT
in Mexico, and CIMMYT scientists have
visited several of the newly
independent nations. In 1998 CIMMYT
opened a regional office in Kazakhstan.
There is now active exchange of
germplasm and information. In the
future, CIMMYT will initiate shuttle
breeding programs with the region. A
joint CIMMYT/Kazakhstan breeding
program to combine quality, drought
tolerance, and disease resistance in high
latitude spring wheat is in the planning
stages. If successful, it would contribute
to the food security not only of
Kazakhstan, but of the whole region.

Eastern Africa. Now in its fourth phase,
the CIMMYT/Canadian International
Development Agency Eastern Africa
Cereals Program (EACP) has as its main
objective to increase maize and wheat
production and productivity in eastern
Africa. During its third phase, the
wheat component of the program
focused heavily on developing
sustainable production systems for the
major wheat growing environments in
the region and on strengthening

national program commitment and
capacity for long-term experimentation.
During 1993-96, Kenya, Ethiopia, and
Uganda released 13 CIMMYT-related
bread wheat and durum wheat
varieties. Studies conducted by the
EACP in collaboration with Ethiopia
and Kenya found that reduced or zero
tillage produced either the same or
better yields than conventional tillage
systems. The EACP also developed
agronomic recommendations to
improve yields and nitrogen use
efficiency in areas that experience
waterlogging problems. An
encouraging fact brought to light in a
recent report by the EACP is that
several decades of breeding durum and
bread wheats from CIMMYT
semidwarf wheats in Ethiopia have
resulted in annual increases of 1.5-2.0%
in yield potential based on rainfed

Improvements in

Wheat Quality

Often wheat quality is perceived to be
important only to large-scale farmers
dedicated to commercial production. In
fact, traits related to quality in wheat
are even more important for many poor
farmers, whose incomes may increase if
they can produce wheat that receives a
price premium for its quality

Several studies have concluded that
wild diploid species carrying A and D
genomes have greater allelic variation
than cultivated wheat for gene loci
controlling glutenin subunits (Waines
and Payne 1987; Lagudah and Halloran

1988; Ciaffi et al. 1992; Lafiandra,
Ciaffi, and Benedetelli 1993; William,
Pena, and Mujeeb-Kazi et al. 1993).
These alien genes offer a potential
means of expanding the number of
allelic variants controlling proteins
with desirable quality effects in wheat.
Several of the synthetic hexaploids
developed from accessions of diploid
Triticeae species (T. tauschii, T.
boeoticum, T. monococcum, and T. urartu)
and durum wheat have been examined
in relation to grain characteristics
associated with end-use quality of
bread and durum wheats. The analyses
revealed that T. tauschii may be used
for substantially increasing the number
of high molecular weight glutenin
(HMWG) subunits present in bread
wheat (HMWG subunit composition is
implicated in the definition of gluten
strength in both bread wheat and
durum wheat) (Payne et al. 1981;
Pogna et al. 1990).
We have also examined variability
for quality (grain hardness, protein
content, and SDS-sedimentation) as
well as the relationship between
quality and HMWG and low molecular
weight glutenin (LMWG) subunit
composition (SDS-PAGE) in 137
accessions of T. dicoccon. Results
confirm previous findings that T.
dicoccon has more diverse genetic
variability for alleles involved in the
synthesis of gluten-type proteins than
cultivated wheat. T. dicoccon should be
considered a good potential source for
improving gluten strength in bread
and durum wheat.
In the past three years, the
frequency of high quality CIMMYT
bread wheats has increased
dramatically. A modification of the
crossing strategy, emphasizing high
quality parents, was implemented in

the early 1990s. Quality testing of
advanced generation breeding
materials was increased over the past
few years. Now these two strategies
have come to fruition. In the near
future, about 75% of CIMMYT's new
bread wheat germplasm will be
competitive for quality standards in
the marketplace.


and Wheat

Improvement: An

Example of


By drawing on the power of
biotechnology, CIMMYT seeks to make
plant breeding more efficient and, in
some cases, to improve wheat in ways
that have eluded conventional
breeding approaches. The comparative
genetic mapping of cereal genomes has
identified a vast amount of conserved
linearity of gene order (Devos and
Gale 1997). This observation is likely to
accelerate the application of
quantitative trait loci (QTL) in wheat,
as well as aid in the identification of
genes required for introgression from
alien species. Given the low number of
loci tagged at present in wheat, the
problems related to developing a high
density map for wheat (Snape 1998),
and the limited progress to identify
QTL for yield in wheat, we believe that
the impact from this linearity on wheat
improvement will be significant.

An extremely positive development
in CIMMYT's efforts to apply
biotechnology to wheat improvement
is participation as a core partner in the
Cooperative Research Centre (CRC) for
Molecular Plant Breeding, established
and supported under the Australian
government's Cooperative Research
Centres Program. The CRC
collaboration features two main
projects. The first projects aims to
identify molecular markers for
resistance to leaf rust and yellow rust.
In line with the rust resistance breeding
strategy described previously,
researchers from CIMMYT and
Australia are looking for minor genes
to create durable resistance. For
CIMMYT's partners in the
international wheat improvement
system, the value of this project is clear.
For Australia, this work will prove
valuable in the event that rust
resistance in its wheat varieties (largely
based on major genes) breaks down, as
has occurred on occasions in the past.

The second project in the CRC
collaboration focuses on introducing,
via transgenics, resistances to some
fungal pathogens of wheat and then
characterizing their effects. An
important aspect of this work is to
increase transformation efficiencies,
which were low at the outset. Rates of
transformation have been significantly
increased (efficiency was 0.2-0.4%
before; now it averages about 1% and
may reach 5% in the near future), and
researchers are proceeding with the
other objectives.

By collaborating with the many
institutes involved with the CRC that
are leaders in molecular genetics in
wheat, CIMMYT can tap into their
expertise in ways that will greatly

benefit many of our partners in the
international wheat improvement
system. Australia will also see positive
results from the collaboration.
According to the last annual report of
the CRC for Molecular Plant Breeding,
"CIMMYT's global field program
provides CRC scientists with the
opportunity to evaluate germplasm
and populations in a wide range of
environments. This makes it much
easier for researchers to develop
molecular approaches to the isolation
of traits than if they were limited solely
to Australia's agro-ecological
environments" (CRC for Molecular
Plant Breeding 1998).

Crop and Natural




When combined with robust, highly
productive crop varieties, it is not
uncommon for improved management
practices to raise farmers' yields twice
and even three times. Strategic research
on crop and natural resource
management leads to improved
farming practices and more sustainable
maize and wheat production systems.
Such research involves a complex
iteration of field studies, crop and soil
modeling, the use of geographic
information systems, and remote
sensing. At CIMMYT, agronomists are
examining nutrient auditing and
strategic fertilizer use; appropriate
strategies for replenishing soil organic
matter (such as green manures and
crop residues); the development of

suitable crop rotations; reduced
tillage; and integrated pest and weed
management. Some of these strategies
are described in the sections that

Improved Input
Use Efficiency
Combining input efficiency with high
yield potential in new cultivars will
allow a farmer to benefit from these
cultivars over a wide range of input
levels. Selection for yield potential
under medium to high levels of
nitrogen has indirectly increased the
efficiency of N uptake in CIMMYT
wheats. Recently released CIMMYT
bread wheat cultivars require less N to
produce a unit of grain than cultivars
released in previous decades (Ortiz
Monasterio et al. 1997). The increase in
nitrogen use efficiency is shown in
Figure 2. Under low N levels in the
soil, N use efficiency increased mainly
due to a higher N uptake efficiency
the ability of plants to absorb N from
the soil-whereas under high N
levels, the N utilization efficiency
the capacity of plants to convert
absorbed N into grain yield

A study initiated in 1994 evaluated
changes in soil nutrients and gas
emission before and after fertilizer
applications and compared alternative
ways of applying nitrogen (Matson,
Naylor, and Ortiz-Monasterio 1998).
The experiment compared the
common practice of Yaqui Valley
farmers with alternatives that
included reducing the amount of
nitrogen applied and changing the
timing of its application. The
researchers found that with the
farmers' practice, relatively high levels
of nitrogen were lost into the

(iai % rIed itImi

I'JiO iSi 6 0 i) iS SO
G(ienoipe \ ea of eIlerase
Figure 2. Grain yield of the historical series
of bread wheats at Cd. Obreg6n, Mexico, at
0 and 300 kg/ha N application.

atmosphere when nitrogen came into
contact with irrigation water, even
before the wheat crop was in the
ground. The best practice reduced the
amount of nitrogen (from 250 to 180
kg/ha, one-third applied at planting
and two-thirds six weeks later) and
produced yields and grain quality
similar to those obtained under the
farmers' practice. The best alternative
practice also saved US$ 55-76/ha
(equivalent to saving 12-17% in after
tax profits). The study shows that it is
possible to reduce nitrogen gas
emissions and fertilizer losses through
appropriate agronomic practices and
at the same time maintain yields.

Bed Planting Systems
A reduced tillage system developed by
farmers and researchers in Mexico's
Yaqui Valley is showing its potential
there and in other irrigated wheat
production environments. In this
system, a crop is grown on raised beds
that are divided by furrows for
irrigation. No soil inversion tillage is
used on the beds. Crop residues are

chopped and left on the surface of the
beds. The system has several
advantages for farmers and the
environment, including:

* Nitrogen can be applied when and
where the wheat plants can use it
most efficiently. Yields improve, and
nitrogen losses into the environment
are significantly reduced.
* Water conservation improves. As
water for agriculture becomes more
scarce in the years to come, water
conservation practices will become
more important for farmers.
Researchers in South Asia and China
report a 30% savings in water use
from using bed planting and
improved weed control.
* Weeds can be controlled by
cultivating between the beds
reducing costs and the need for
* Residues are returned to the soil
without burning, which is beneficial
to the environment.
* The beds can be used cycle after
cycle. Farmers avoid the financial and
environmental costs of making
repeated passes with a conventional
plow during land preparation.

Prototype machinery for this bed
planting system has been designed
and tested in Mexico and in Asia. The
prototypes are modifications of
standard agricultural equipment and
are expected to be affordable for poor
farmers. Mexican farmers reportedly
save 30% on their production costs
when they use the bed planting
system. Some 10,000 farmers are
thought to use the system in Mexico,
and the number of farmers who are
using bed planting is growing in South
Asia and China as well. In fact, in
parts of China some farmers find the

technology so valuable that in the
absence of equipment they form the
beds by hand.

Farmer Participatory
Over the past few years, CIMMYT has
significantly increased its investment
in farmer participatory research for
natural resource management (that is,
in the development of productivity
enhancing, resource-conserving
practices for maize and wheat systems,
with beneficial impacts on soils, water,
and agroecosystem diversity). Farmer
participatory research is a tool for a
purpose: the development of
sustainable practices that improve
resource quality while raising system
productivity. CIMMYT is moving
aggressively to mainstream the use of
this tool for these important ends. For
example, in irrigated areas in northern
Mexico, CIMMYT has long
collaborated with farmers in the
development of the bed planting
systems described earlier.

In Asia, CIMMYT works with the
other members of the Rice-Wheat
Consortium for the Indo Gangetic
Plains to foster farmer experimentation
on reduced and zero tillage strategies
for establishing wheat after rice.
Farmer groups have assessed
alternative tillage and sowing
implements and wheat establishment
strategies, and they have been
encouraged to develop their own
innovations and adaptations.
Minimum tillage practices are
spreading in Bangladesh, and farmers
in the western part of the Indo
Gangetic Plains are beginning to use
zero tillage. Farmers report earlier
sowing, higher yields with lower levels
of inputs, and improved possibilities

for diversifying cropping patterns
away from a continuous rice-wheat
rotation-with numerous
agroecological benefits.

In Bolivia, we are collaborating
with farmer groups to develop zero
tillage/mulch systems suitable for
smallholders (2-5 ha) in the high inter
Andean valleys. These farmers
produce one crop of wheat each year
in monoculture or in rotation with
potatoes, faba beans, peas, and/or
barley. Research focuses on evaluation
of straw cover to increase rainfall use
efficiency. Results are extremely
encouraging: crop residue retention
generally increases yields and reduces
risk, two important objectives for
Bolivia's small-scale, subsistence
farmers. Researchers also participate
in a project to develop a small,
animal-drawn, no-till seed drill for
sowing cereals into surface residues,
and results are very positive
(CIMMYT 1999).


Management Tools

for Sustainable


Researchers have always believed in
the value of sharing information more
widely, but the limitations of
information technology have not
made this easy. CIMMYT now offers a
widening array of information
management tools to researchers in
many disciplines.

For example, the International
Wheat Information System (IWIS) is a
relational database available on CD
which gives each genotype a unique
identifier and provides extensive
pedigree and performance data. The
Genetic Resources Information
Package (GRIP), designed in
conjunction with Australian partners,
allows IWIS users to locate seed
samples in wheat germplasm stocks
in a number of collections around the
world and provides an abbreviated
version of the IWIS pedigrees. The
International Crop Information
System (ICIS) is a data management
tool that builds on IWIS. It contains
information on several crops in
addition to wheat. The core of ICIS is
a relational database structure that
stores data on plant genetic resources,
pedigrees, field and laboratory
evaluations (including molecular
information), and auxiliary data on
locations, institutions, and people.
Simple geographic information
functions are being incorporated into
ICIS, and a tool for exporting data to
crop simulation models is also under

One challenge to sharing
information more widely is to
provide access to cutting-edge
geographic information system (GIS)
tools for non-GIS users, especially
those in Africa. African researchers
need spatially referenced data on
climate, soils, infrastructure, crop
distribution, and the natural resource
base, in part to ascertain the extent to
which their site-specific research may
have relevance to larger areas. The
Africa Country Almanacs contain
such base data, along with the most
commonly requested maps, plus
search and viewing tools, on a single

compact disc. Almanacs have been
developed for 12 African countries,5
some of which have requested follow
on demonstrations and training for
their research staff. Now all researchers
can have access to these powerful GIS
tools, not just a few specialists in a
central office.

The Spatial Characterization Tool
(SCT) developed by CIMMYT and
Texas A & M University goes a long
way towards addressing the problem
of "site specificity" in natural resources
management research. Site researchers
can now quickly perform "site
similarity analysis," identifying areas
with environments resembling that of
their site. When applied to sites in
Bolivia, this analysis uncovered
environmentally similar areas within
Bolivia; in neighboring countries (e.g.,
Chile, Brazil); within the Americas
(e.g., Mexico); and even in other
regions of the world (Ethiopia,
Lesotho). Scientists in these diverse
locations find that they have much to
share about technology performance
and the consequences of technical
change for system productivity and

These information management
tools help encourage research
integration, explore the prospective
performance of new technologies, and
overcome site specificity. However, like
all information management tools, they
need data. A final challenge is how to
preserve, organize, and make available
to researchers the rich array of data
often generated by research,
particularly in natural resource
management research. CIMMYT is

5 Including three important wheat
producing nations: Ethiopia, Kenya,
and Zimbabwe.

developing an answer to this set of
challenges: the Sustainable Farming
Systems Database (SFSD). Non
governmental organizations are using
the SFSD prototype to organize
information on the global experience
with green manure cover crops. As the
SFSD matures, its uses will be
virtually infinite.


The strategies we have just outlined
could make the difference between a
sustainable future, with food and
economic opportunity available for
the majority, and a future of scarcity,
with survival seriously compromised
for most people. Successful,
sustainable agriculture can help create
the purchasing power and
employment that will ensure food
security and help eradicate poverty.
We believe that the risks of ignoring
agricultural development will be far
higher than the risks of deciding to
create a sustainable future for us all.

The world has faced a similar
choice before, when a decision was
made to sow the new semidwarf
wheats in India in the hope that their
higher yields would prevent a famine
as great as the devastating Bengal
famine of 1943. That decision
transformed agriculture and the way
that agricultural research was
conducted. Today CIMMYT and its
partners join forces in one of the
world's most ambitious endeavors:
we participate in a global wheat
improvement system that continues to
better the lives of millions of poor

farmers and consumers in
developing countries. The impact of
that system is well documented
(Byerlee and Moya 1993; Maredia
and Byerlee 1999; CIMMYT 1999). In
the most recent period, 1991-97,
almost 90% of the spring bread
wheat varieties released by national
agricultural research systems had
CIMMYT ancestry (Figure 3).
Virtually all (98%) of the spring
durum wheats released by national
programs in 1991-97 had CIMMYT
ancestry (Figure 4). Farmers now
plant almost 80% of the developing
world's spring bread wheat area to
CIMMYT-related wheats (Figure 5).

NARS crosses with
at least one CIMMYT
parent, 19% NARS crosses
with some
ancestry, 5%

r' Tall
varieties, 2%

Figure 4. Ancestry of spring
durum wheat varieties
released by national
programs, 1991-97.
Source: CIMMYT wheat
impacts database.

NARS crosses with at
least one CIMMYT
parent, 28%

CIMMYT crosses
(some re-selected by
NARSs), 56%

NARS crosses
with some
ancestry, 5%

L with other
S ancestry, 8%

varieties, 3%

Figure 3. Ancestry of spring bread wheat
varieties released by national programs,
Source: CIMMYT wheat impacts database.

Percentage of total spring
bread wheat area


Tall with pedigree
60 -
Other semidwarf
At least one
20 CIMMYT parent

n _cross

Figure 5. Area planted to spring bread
wheat in developing countries, 1997.
Source: CIMMYT wheat impacts

A New Research Paradigm
for New Research Impacts
These research impacts are reassuring,
but much remains to be done. When
our colleague Norman Borlaug
accepted the Nobel Peace Prize for his
achievements in bringing about the
Green Revolution in wheat, he
cautioned that the Green Revolution
"has not transformed the world into
Utopia. None are more keenly aware of
its limitations than those who started it
and fought for its success. ... Above
all, I cannot emphasize too strongly the
fact that further progress depends on
intelligent, integrated, and persistent
effort" (CIMMYT 1970).

Borlaug's observation remains true.
If we are to make progress toward
sustainable food security, we must take
his advice and change the way we
plan, conduct, and communicate about
research. We must blend very
specialized research disciplines in
teams of scientists seeking appropriate
outcomes that have an immediate
impact in farmers' fields. It is from
these fields that food supplies must
come for the foreseeable future. The
farmer is the ultimate systems-oriented
operator, juggling biological, economic,
environmental, and social factors. In
such circumstances, isolated
interventions are of limited value at
best; all too often, they make things

These interventions will be based
on a new, integrative research
paradigm that focuses on the elements
of the GxExMxP equation mentioned
earlier: the best genotypes (G), in the
right environments (E), under
appropriate crop management (M),
generating appropriate outcomes for
people (P). Everyone who seeks to

foster sustainable agriculture in
developing countries should recognize
the interdependence of these factors,
because most organizations by
themselves cannot contribute fully to
each aspect of GxExMxP. Partnerships
and consortia that assemble the best
possible teams to execute the GxExMxP
approach will underpin the timely and
successful achievement of sustainable
farming systems and future food

The Shape of Things
to Come
Given these requirements, what will
agricultural research look like in the
new millennium? Every member of the
international wheat improvement
system and the farmers and
consumers who depend on it-will be
affected by changes in international
research in the years to come. Which
forces are likely to shape the way that
research is done-either by
contributing to or detracting from the
integrative research paradigm we have
just described?

For decades, collaboration has been
the mainspring of the international
wheat improvement system. None of
the achievements described in this
paper could have been attained
without it. Gains from conventional
breeding will continue to be significant
in the next two decades or more
(Duvick 1996), but these are likely to
come at a higher cost than in the past.
Research managers and policy makers
are increasingly concerned that the
very open, collaborative networks that
have sustained the wheat improvement
system will become far more
circumscribed in coming years.

Rasmussen (1996) has stated that
nearly half of the progress made by
breeders in the past can be attributed to
germplasm exchange. In recent surveys
of wheat breeders (Braun et al. 1998;
Rejesus, van Ginkel, and Smale 1996),
more than 80% of respondents
expressed concern that plant variety
protection (PVP) and plant or gene
patents will restrict access to
germplasm, with deleterious
consequences for future breeding
achievements. Regional and
international nurseries are an efficient,
low-cost means of gathering data from
varied environments and exposing
germplasm to diverse pathogen
selection pressures, while providing
access to germplasm and promoting
germplasm exchanges. Breeders use
cooperative nurseries extensively in
their crossing programs, but the
number of such nurseries has been
greatly reduced during the past
decade, partly because of increasing
restrictions on germplasm exchange.

Recent developments in
biotechnology for plant improvement
have motivated much of the concern
over PVP and other forms of
intellectual property rights (IPR), as
well as concern over germplasm
exchange and developing nations'
access to novel agricultural
technologies. That debate promises to
pale in comparison to another
biotechnology-inspired debate,
however, that has been prominent in
the media.

The debate over the ethical uses of
biotechnology has shifted to the
agricultural sector. A furor over
genetically modified plants (focusing
on uncertainty over their potential
effects on human health and the

environment) has swept across
Europe, where "the public's
perception of risk far outweighs its
view of the possible benefits" (The
Economist, 19 June, 1999). Within
development circles, some argue that it
is too risky to use genetic engineering
to solve poor people's problems
because we may be unaware of future
side effects. Others question whether it
is ethical to withhold solutions to
problems that cause millions of
children to die from hunger and
malnutrition. Clearly we must seek
acceptable levels of biosafety before
releasing products from modern
science, but it is critical that the risks
associated with the solutions be
weighed against the ethics of not
making every effort to solve food and
nutrition problems.

These highly public-and highly
charged-debates make it easy to lose
sight of another trend in the research
environment that is almost more
worrying. For a host of reasons, many
national agricultural research systems
have become weaker over the past two
decades rather than stronger. At the
international level, public support for
broad research initiatives, such as
CIMMYT's improvement of wheat
germplasm for the major
environments in the developing
world, has diminished as public
research investments have increasingly
focused on more narrowly targeted
projects. Under these circumstances,
can we reasonably expect the public
sector to be an effective advocate on
behalf of the poorest constituents of
society? Will the declining resources
commanded by the public sector
interfere with germplasm testing and

exchange even more than the trends
described earlier? Given the vast
resources commanded by private
research organizations, what is the
future role of the public sector in crop
improvement research?

Despite these uncertainties in the
research environment, our ultimate
objective remains clear. We know that
to ensure food security in the 21st
century, the sustainable intensification
of agriculture in farmers' fields is
essential. With 200 people added each
minute to our population, and with all
of us, rich and poor alike, dependent
on a shrinking agricultural resource
base, sustainable intensification is the
only practical and appropriate choice
for the foreseeable future. The new

millennium holds out incredible
promise-superior technology,
unprecedented access to information,
economic growth-but if these serve
only to widen the gap between the
"haves" and "have-nots," between the
North and South, then what will we
have gained? Of the many issues
surrounding the future of international
agriculture, this is perhaps the most
important. It is the central issue that
motivates CIMMYT's research agenda,
and it will remain at the forefront of all
of our future efforts.


Borlaug, N.E., and C.R. Dowswell. 1997. The acid
lands: One of agriculture's last frontiers. In
A.C. Moniz et al. (eds.), Plant-Soil Interactions
at LowpH. Brazil: Brazilian Soil Science
Society. Pp. 5-15.
Bramel-Cox, PJ., T. Barker, F. Zavala-Garcia, and
J.D. Eastin. 1991. Selection and testing
environments for improved performance
under reduced-input conditions. In Plant
Breeding and Sustainable Agriculture:
Considerations for OCr. I and Methods.
CSSA Special Publication No. 18. Madison,
Wisconsin: CSSA and ASA. Pp. 29-56.
Braun, H.-J., H. Ekiz, V Eser, M. Keser, H. Ketata,
G. Marcucci, A.I. Morgounov, and N.
Zencirci. 1998. Breeding priorities of winter
wheat programs. In H.-J. Braun, F. Altay,
W.E. Kronstad, S.P.S. Beniwal, and A. McNab
(eds.), Wheat: Prospects for Global Improvement.
Dordrecht, the Netherlands: Kluwer
Academic Publishers. Pp. 553-560.
Byerlee, D., and P. Moya. 1993. Impacts of
International Wheat Breeding Research in the
Developing World, 1966-1990. Mexico, D.F.:
Calhoun, D.S., G. Gebeyehu, A. Miranda, S.
Rajaram, and M. van Ginkel. 1994. Choosing
evaluation environments to increase wheat
grain yield under drought conditions. Crop
Science 34: 673-678.
Ciaffi, M., L. Dominici, D. Lafiandra, and E.
Porceddu. 1992. Seed storage proteins of
wild wheat progenitors and their
relationships with technological properties.
Hereditas 116: 315-322.
CIMMYT. 1970. The Green Revolution: Peace and
Humanity. Norman E. Borlaug, 1970 Nobel
Peace Price. Mexico, D.F.: CIMMYT.
CIMMYT. 1986. Veery 'S': Bread Wheats for Many
Environments. Mexico, D.F.: CIMMYT.
CIMMYT. 1999. A Sampling of CIMMYT Impacts,
1999: New Global and Regional Studies.
Mexico, D.F.: CIMMYT.
Cooper, M., D.E. Byth, and D.R. Woodruff. 1994.
An investigation of the grain yield
adaptation of CIMMYT wheat lines to water
stress environments in Queensland. II.
Classification analysis. Agricultural Research
CRC (Cooperative Research Centre) for
Molecular Plant Breeding. 1998. Cooperative
Research Centre for Molecular Plant Breeding:
Annual Report 1997/98. Adelaide, Australia:
CRC for Molecular Plant Breeding.
Devos, K.M., and M.D. Gale. 1997. Comparative
genetics in the grasses. Plant Molecular
Biology 35: 315.

Duvick, D.N. 1990. Ideotype evolution of hybrid
maize in the USA, 1930-1990. In Vol. II of
ATTI Proceedings, National Maize Conference:
Research, Economy, Environment. Bologna,
Italy: Centro Regionale per la
Sperimentazione Agraria, Pozzuolo del
Friuli Edagrocole s.p.a. Pp. 557-570.
Duvick, D.N. 1992. Genetic contributions to
advances in yield of US maize. Maydica 37:
Duvick, D.N. 1996. Plant breeding, an
evolutionary concept. Crop Science 36: 539
Economist. 1999. "Genetically Modified Food:
Food for Thought," 19 June.
Ehdaie, B., J.G. Waines, and A.E. Hall. 1988.
Differential responses of landrace and
improved spring wheat genotypes to stress
environments. Crop Science 28: 838-842.
Fischer, R.A., D. Rees, K.D. Sayre, Z. Lu, A.G.
Condon, A. Larque-Saavedra, and E. Zeriger.
1998. Wheat yield progress is associated
with higher stomatal conductance, higher
photosynthetic rate, and cooler canopies.
Crop Science 38: 1467-1475.
ICARDA (International Center for Agricultural
Research in the Dry Areas). 1993. Cereal
Program. Annual Report for 1992. Aleppo,
Syria: ICARDA.
Lafiandra, D., M. Ciaffi, and S. Benedetelli. 1993.
Seed storage proteins of wild wheat
progenitors. In A.B. Damiana (ed.),
Biodiversity and Wheat Improvement. New
York: John Wiley Pp. 329-340.
Lagudah, E.S., and G.M. Halloran. 1988.
Pi, 1..-. I,. ,., relationships of Triticum
tauschii the D genome donor to hexaploid
wheat. I. Variations in HMW subunits of
glutenin and gliadins. Theoretical and Applied
Genetics 75: 592-598.
Maredia, M.K., and D. Byerlee (eds.) 1999.
CIMMYT Research Report No. 5. Mexico, D.F.:
CIMMYT I.., I ........ I
Matson, PA., R. Naylor, and I. Ortiz-Monasterio.
1998. Integration of environmental,
agronomic, and economic aspects of
fertilizer management. Science 280: 112-114.
McFadden, E.S. 1930. A successful transfer of
emmer characters to vulgare wheat. Journal of
the American Society of Agronomy 22: 1020
Ortiz-Monasterio, J.I., K.D. Sayre, S. Rajaram,
and M. McMahon. 1997. Genetic progress in
wheat yield and nitrogen use efficiency
under four nitrogen rates. Crop Science 37:
898 904.

Payne, P.I., K.G. Corfield, L.M. Holt, and J.A.
Blackman. 1981. Correlations of certain high
molecular-weight subunits of glutenin and
breadmaking quality in progenies of six
cross of bread wheat. Journal of the Science of
Food and Agriculture 32: 51-60.
Pinstrup-Andersen, P., and R. Pandya-Lorch.
1997. Can Everybody Be Well Fed by 2020
without Damaging Natural Resources? First
Distinguished Economist Lecture. Mexico,
Pogna, N.E., J.C. Autran, F. Mellini, D. Lafiandra,
and P. Feillet. 1990. Chromosome 1B
encoded gliadins and glutenin subunits in
durum wheat: Genetics and relationship to
gluten strength. Journal of Cereal Science 11:
Rajaram, S., and M. van Ginkel. 1995. Wheat
breeding methodology: International
perspectives. Paper presented at the 20h
Hard Red Winter Wheat Workers Workshop,
Oklahoma City, USA.
Rasmussen, D.C. 1996. Germplasm is paramount.
In M.P Reynolds, R. Rajaram, and A. McNab
(eds.), Increasing Yield Potential in Wheat:
Breaking the Barriers. Mexico, D.F.: CIMMYT.
Pp. 28-35.
Rees, D., K. Sayre, E. Acevedo, T.N. Sanchez, Z.
Lu, E. Zeiger, and L. Limon. 1993. Canopy
Temperatures of Wheat: Relationship with Yield
and Potential as a Technique for Early
Generation Selection. Wheat Special Report
No. 10. Mexico, D.F.: CIMMYT.
Reeves, T.G. 1998. Sustainable Intensification of
Agriculture. Mexico, D.F.: CIMMYT.
Reeves, T.G. 1999. Intensification for the nine
billion. Nature Biotechnology (supplement) 17:
Reeves, T.G., P. Pinstrup-Anderson, and R.
Pandya-Lorch. 1997. Food Security and the
Role of Agricultural Research. Mexico, D.F.:
Rejesus, R.M., M. van Ginkel, and M. Smale.
1996. Wheat Breeders'Perspectives on Genetic
Diversity and Germplasm Use. Wheat Special
Report No. 40. Mexico, D.F.: CIMMYT.
Reynolds, M.P, M. Balota, M.I.B. Delgado, I.
Amani, and R.A. Fischer. 1994. Physiological
and morphological traits associated with
spring wheat yield under hot, irrigated
conditions. Australian Journal of Plant
Physiology 21: 717-730.
Reynolds, M.P, R.P Singh, A. Ibrahim, O.A.A.
Ageeb, A. Larque Saavedra, and J.S. Quick.
1998. Evaluating physiological traits to
complement empirical selection for wheat in
warm environments. Euphytica 100: 85-94.

Rosegrant, M.W., M.A. Sombilla, R.V. Gerpacio,
and C. Ringler. 1997. Global food markets
and US exports in the twenty-first century.
Paper presented at the Illinois World Food
and Sustainable Agriculture Program
Conference, Meeting the Demand for Food
in the 21st Century: Challenges and
Opportunities, 28 May, University of
Illinois, Urbana-Champaign.
Smale, M., R.P Singh, K. Sayre, P. Pingali, S.
Rajaram, and H.J. Dubin. 1998. Estimating
the economic impact of breeding
nonspecific resistance to leaf rust in modern
bread wheats. Plant Disease 82(9): 1055-1061.
Snape, J.W. 1998. Golden calves or white
elephants? Biotechnology for wheat
improvement. Euphytica 100: 207-217.
Uddin, N., B.F. Carver, and A.C. Clutter. 1992.
Genetic analysis and selection for wheat
yield in drought-stressed and irrigated
environments. Euphytica 62: 89-96.
UNDP (United Nations Development
Programme). 1997. Human Development
Report 1997. [www.undp.org/hdro/
van Ginkel, M., D.S. Calhoun, G. Gebeyehu, A.
Miranda, C. Tian-you, R. Pargas Lara, R.M.
Trethowan, K. Sayre, J. Crossa, and S.
Rajaram. 1998. Plant traits related to yield of
wheat in early, late, or continuous drought
conditions. Euphytica 100: 109-21.
Villareal, R.L., E. del Toro, A. Mujeeb-Kazi, and
S. Rajaram. 1995. The 1BL/1RS chromosome
translocation effect on yield characterization
in a Triticum aestivum L. cross. Plant Breeding
Waines, J.G., and P.I. Payne. 1987.
Electrophoretic analysis of the high
molecular-weight glutenin subunits of
Triticum monococcum, T uartu, and the A
genome of bread wheat (T aestivum).
Theoretical and Applied Genetics 74: 71-76.
William, M.D.H.M., R.J. Pena, and A. Mujeeb
Kazi. 1993. Seed protein and isozyme
variations in Triticum tauschii (Aegilops
squarrosa). Theoretical and Applied Genetics 87:
World Bank. 1997. World Development Indicators
1997. New York: Oxford University Press.
Zavala-Garcia, F., PJ. Bramel-Cox, J.D. Eastin,
M.D. Witt, and D.J. Andrews. 1992.
Increasing the efficiency of crop selection
for unpredictable environments. Crop
Science 32: 51-57.


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