Title: Research highlights
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00071929/00008
 Material Information
Title: Research highlights
Uniform Title: Research highlights (East Lansing, Mich.)
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Bean/Cowpea Collaborative Research Support Program
Publisher: Michigan State University Bean/Cowpea CRSP
Place of Publication: East Lansing
Publication Date: 1984-
Subject: Beans -- Research -- Periodicals -- Africa   ( lcsh )
Beans -- Research -- Periodicals -- Latin America   ( lcsh )
Cowpea -- Research -- Periodicals -- Africa   ( lcsh )
Cowpea -- Research -- Periodicals -- Latin America   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
periodical   ( marcgt )
Statement of Responsibility: Michigan State University Bean/Cowpea CRSP.
Dates or Sequential Designation: Vol. 1, no. 1 (1984)-
General Note: Title from caption.
Funding: Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
 Record Information
Bibliographic ID: UF00071929
Volume ID: VID00008
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 - 13864898

Full Text

Michigan State University Bean/Cowpea CRSP

Vol. 2 No. 3 1985

Kenya/University of California-Davis /Webster

Tepary Beans:
A Resource for Improvement of Common Beans

Barbara D. Webster
Department of Agronomy and Range Science anm
University of California, Davis
Davis, CA 95616

Water management, availability and con-
servation has been called the global en-
vironmental issue of the 1980s, and the rising
energy cost of pumping water has brought
about a resurgence of interest in crops
which grow well on rain, runoff or minimal
irrigation. Among these is the tepary bean
(Phaseolus acutifolius A. Gray), a desert-
adapted plant often classified as "drought
escaping," since it is capable of completing
its life cycle prior to most late season
droughts. The tepary is routinely grown in
the American Southwest and adjacent
Mexico where it sets pods and matures
seeds at temperatures too high and under
conditions too dry for common beans
(Phaseolus vulgaris L.) to tolerate. The Na-
tional Academy of Sciences in 1979 recom-
mended continued study of the tepary as a
subsistence crop in arid areas of Africa,
South America, Asia and the arid Pacific and
Caribbean islands. With support from the
Bean/Cowpea Collaborative Research Sup-
port Program (CRSP), investigators at the
University of California at Davis and River-
side and at the University of Nairobi in
Kenya have been working together to
characterize teparies, common beans and
common bean/tepary hybrids which are
adapted to the semiarid, drought-prone
regions of Kenya.
Teparies exhibit many traits which could
be of value if transferred to the cultivars of
common beans which are presently grown
in Kenya or which are not now adapted to

J. Giles Waines
d Department of Botany and Plant Sciences
University of California, Riverside
Riverside, CA 92521

semiarid environments. In addition to their
widely touted drought and heat tolerance,
teparies tolerate high concentrations of salt
and boron in the soil. They also exhibit resis-
tance to charcoal rot (caused by Mac-
rophomina phaseolina [Tassi] Goid) and to
Xanthomonas phaseoli (E.F. Sm.) Dows, the
bacterium which causes common blight of
The adaptation of common beans to
semiarid regions is comparatively poor, al-
though they are widely grown in such areas
in Kenya and in other parts of the world. If
the potential cross compatibility between
tepary and common beans were exploited, it
is possible that a combination of characters
might result which would transform the
biological efficiency of common beans in
semiarid areas. This is a tall order, however,
because there is not inherently a substantial
degree of reproductive affinity among
species of Phaseolus.
At the University of California at Riverside,
Drs. Claire Thomas and Giles Waines have
made considerable progress in their pro-
gram to develop bean/tepary interspecific
hybrids and progeny from them. The first
difficulty to be overcome was that of produc-
ing hybrid seed on the plant, since hybrid
embryos typically abort before seed is fully
developed unless embryos are cultured.
One exception occurred in their crosses of a
wild common bean, PI 325676, with several
wild tepary lines. Pods from such crosses
developed normally and yielded mature

Funded through USAID/BIFAD Grant No. AID/DSAN-XII-G-0261

seed. Some of this seed germinated and
hybrid plants were obtained. These could be
distinguished from the parents by embryo
size and shape, leaf shape, growth habit,
flower color and bract position and size. All
other hybrid genotypes required embryo
culture to salvage abortive embryos. Con-
siderable success has now been achieved by
Thomas and Waines in rearing vigorous
adult interspecific hybrid plants, using either
P. vulgaris or P. acutifolius as female parent,
by use of embryo culture. The techniques
involve excision of the embryos 14-24 days
after pollination and culture on a medium
containing 30-40 g/l sucrose plus salts, min-
erals and vitamins. Of the large number of
lines of both species used in their crosses, it
is noteworthy that either the tepary P1321638
or the common bean 'Masterpiece,' or both,
were parents of 29 of 39 mature F1 hybrid
plants. In addition, all fertile progeny had
one or both of these parents.
Field trials have been underway for the
past four years at UC Davis and Riverside

and at the University of Nairobi to assess the
degree of drought and/or heat tolerance
which may have been transferred from tep-
ary beans into common beans. At UC Davis
and at the University of Nairobi, CRSP inves-
tigators have been using a line-source
sprinkler system designed to deliver mea-
sured amounts of water to plants growing at
increasingly greater distance from the
source. They have collected data on a range
of morphological and physiological charac-
teristics exhibited by teparies, common
beans and hybrids throughout the growing
season, and they have assessed the potential
for adaptation to the semiarid regions of
Kenya. Since drought tolerance is exceed-
ingly complex, both morphological and
physiological components of the system are
being evaluated in the hope that these will
integrate to achieve a high degree of
drought tolerance. As some of the many
components are pinpointed to be of major
importance, some success in drought toler-





FIGURE 2: Field-grown common beans and tepary 10 days atter
germination at minimum irrigation at UC Davis. 'Blan' is the locally
grown bean control. 'Mwezi moja' and 'GLP2' are widely grown beans
in Kenya. Note the extensive root and shoot system of the vigorous,
rapidly growing tepary.

FIGURE 1: Dr. Barbara D. Webster, Professor of
Agronomy, University of California, Davis and
Principal Investigator of the Bean/Cowpea CRSP
Kenya project; and Dr. J. Giles Waines, Professor of
Botany and Plant Sciences, University of California,
Riverside and Co-Investigator of the project.

FIGURE 4: Common bean-tepa
agronomy fields at UC Davis.

: : 1 -


ance enhancement is being realized.
The UC Davis field data have shown, for
example, that it is not only the widely rec-
ognized depth of the tepary root system
which is important in relation to drought
tolerance, but also the rapidity of establish-
ment of the root system and the concomi-
tant rapid production of leaves. In the ear-
liest stages of its development, the extent of
growth of the root and the shoot system of
the tepary dramatically exceeded that of the
common beans tested, including the widely
grown Kenyan cultivar 'Mwezi moja.' This
early, vigorous growth of tepary sustained
the plants in the field during the growing
season at water levels lower than those re-
quired for the continued growth of the
common beans tested. The teparies also
flowered and matured earlier than the com-
mon beans. Additional measurements to as-
sess drought tolerance have included, e.g.,
fresh and dry weights, leaf water potential,
cuticle deposition, leaf angle, time to 50



percent flowering, pods set and matured,
seed size and weight, nitrogen fixation,
starch deposition and stomatal resistance.
The extent to which these characteristics are
differentially expressed in teparies, common
beans and bean/tepary hybrids under differ-
ing water regimes suggests the relative im-
portance of individual traits in relation to
drought tolerance.
The semiarid Eastern Province of Kenya is
now in its third rainless "rainy season." Evi-
dences of the drought are readily apparent:
farm fields are parched and gray and a hot,
dry wind blows dust clouds across the land.
The need to enhance the drought tolerance
of the crops grown regularly by the subsis-
tence farmers, especially the beans which
are a major protein source, is patently evi-
dent. This CRSP-sponsored research on the
potential of common beans and teparies for
semiarid areas holds promise for crop im-
provement, increasing the range of adapta-
tion and drought tolerance of common
beans, teparies and their hybrids.


242-46 i

FIGURE 3: Dr. Waines making common
bean-tepary crosses in the greenhouse at
UC Riverside.

segregates growing in the

Selected References

Al-Yasiri, S.A. and D. P. Coyne. 1966. Interspecific
hybridization in the genus Phaseolus. Crop Sci.

Cory, Cynthia L. and Barbara D. Webster. 1983.
Screening of Phaseolus vulgaris and Phaseolus
acutifolius for drought tolerance. In: Improve-
ment of drought and heat tolerance of disease re-
sistant beans in semiarid regions of Kenya. Annual
Report, Bean/Cowpea CRSP 1983. pp. 2-25.

Cory, Cynthia L. and Barbara D. Webster. 1984. As-
sessment of drought tolerance in cultivars of
Phaseolus vulgaris and P. acutifolius. HortScience

Coyne, D. P. and M. L. Schuster. 1972. Genetics of tol-
erance to halo blight, common blight and bacte-
rial wilt in beans. Eucarpia 120-130.

National Academy of Sciences, National Research
Council. 1979. Tropical legumes: resources for the
future. National Academy of Sciences, Washing-
ton, D. C.

Pratt, R. C. 1983. Gene transfer between tepary and
common beans. Desert Plants 5:57-63.

Thomas, Claire V., R. M. Manschardt and J. Giles
Waines. 1983. Teparies as a source of useful traits
for improving common beans. Desert Plants

Thomas, Claire V. and J. Giles Waines. 1984. Fertile
backcross and allotetraploid plants from crosses
between tepary beans and common beans. J.
Heredity 75:93-98.

For further information contact:
Bean/Cowpea CRSP
200 Center for International Programs
Michigan State University
East Lansing, Michigan 48824-1035
Telephone: (517) 355-4693
Telex: 810-251-0737

An international community of persons, institutions,
agencies and governments committed to collectively
strengthening health and nutrition in developing
countries by improving the availability
and utilization of beans and cowpeas

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