ABIOTIC
STRESS
Significance
Efficiency in water usage and ability to grow under heat stress are
important for the long-term viability of peanut production in Texas. In
West Texas, peanut is grown under irrigation, necessitated by the low rainfall
(18 inches per annum in the Lubbock area). Energy costs for irrigation
are a significant cost in peanut production, and availability of underground
water limits where peanut can be cultivated. In the long term, it is estimated
that at the current rate of agricultural and urban use of water, the High
Plains Aquifer extending from South Dakota through West Texas could be
depleted within 30 to 40 years. In South and Central Texas, peanut is frequently
grown as a rainfed crop, and is subjected to periodic droughts and associated
aflatoxin contamination. Peanuts have also been observed to suffer from
high (100°+) temperatures even when irrigated sufficiently. Furthermore,
there is evidence that the new high-oleic:linoleic cultivars are particularly
susceptible to heat stress. The related effects of water and temperature
stress have hurt peanut production in certain years, especially in the
2000 growing season, when heat, drought, and an early freeze resulted in
one-third of the acres planted in Texas not being harvested.
Goals
Our long-term goal is the development of improved varieties that can be
grown even under stress conditions. Our hypothesis is that it is
possible to identify peanut germplasm with some heat and drought tolerance,
and that it is possible to use this as parents in varietal development.
Towards this end, we are working on three complementary approaches.
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Drought tolerance. Our short-term objective is to study
cultivated accessions and germplasm identified by other as having some
drought-tolerance traits. We will determine whether any of this material
may be of use in West Texas; data may also be of use to collaborators from
other states. Once promising germplasm is identified, we hope to
use it in an improvement program. This collaboration involves Drs.
Mike Schubert and Dana Porter (Texas A&M University), Diane Rowland
(USDA- NPRL, Georgia), and Corley Holbrook (USDA- Georgia).
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Heat tolerance. We will study additional germplasm
to classify major cultivars according to degree of heat tolerance, then
determine the genetics of the heat tolerance trait. Of particular
importance is determining whether it is possible to develop heat-tolerant
high O/L lines. We are cooperating with Dr.
John J. Burke in determining heat tolerance.
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Maturity. As mentioned under Seed Quality, we are working
on development of an early-maturing peanut. This has the potential
to reduce irrigation requirements and costs by thousands of dollars annually
per farmer.
Research Program and Results
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Drought tolerance. We are growing 30 runner and 4 Spanish/Valencia
lines at the West Texas Peanut Growers Research Farm under standard and
reduced irrigation. Irrigation requirements for drought stress have
been esablished by Drs.
A. Michael Schubert and Dana Porter. In the summer of 2002,
we have seen large differences in flowering and canopy temperature due
to drought stress. We are also determining changes in osmotic potential
and will have measurements of carbon isotope discrimination, specific leaf
area, harvest index, yield, and transpiration efficiency later this year.
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