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United States Department of Agriculture

Agricultural Research Service

Research Project: PHYSIOLOGICAL MECHANISMS THAT DETERMINE CROP RESPONSE TO IRRIGATION, DISEASE AND PRODUCTION PRACTICES
2012 Annual Report


1a.Objectives (from AD-416):
1. Identify physiological drought responses to quantify water-use efficiency and other physiological characteristics that influence peanut yield and quality(aflatoxin contamination, flavor, maturity) and how these traits may differ among resistant and susceptive cultivars.

2. Characterize the physiological processes and genetic expression changes that impact a level of disease tolerance to Tomato spotted wilt virus in peanuts.


1b.Approach (from AD-416):
The effectiveness of most production practices is evaluated at harvest by examining final yield. However, an understanding of the mechanisms that drive these final yield numbers is vital in determining the efficacy of production strategies and technologies. Most causal mechanisms are physiologically based; therefore, an examination of the physiological response to the production environment can help determine how production practices succeed or fail. Research will be conducted to investigate and improve the understanding of the physiological responses to environment, climate, and production practices that ultimately determine peanut yield and quality. Major emphasis will be directed towards examining the effects of irrigation type and amount on peanut physiological water use and evaluating wateruse efficiency under varying water environments. Emphasis will also be placed on plant and kernel susceptibility to aflatoxin contamination and tomato spotted wilt virus, and their effects on water use and other plant and kernel physical characteristics. A quality natural resource base is a vital factor in the viability of rural economies to sustain agricultural productivity. Available water supply is being stretched by rapidly growing demands for water by urban populations, irrigated agriculture, industry/energy sectors, and in-stream flow requirements. The dilemma for producers and local economies is finding solutions that help reduce irrigation and natural resource consumption while at the same time maintaining and or enhancing producer net returns.


3.Progress Report:
Research plots were established on controlled rainout shelters to determine the level of drought resistance in different newly introduced peanut germplasms. Plants were subjected to water deficit at various times during peanut development to determine critical stages of peanut growth that will affect peanut yield and quality. Ongoing evaluations of peanut breeding lines are being conducted. For the current crop year in 2012, 1,800 breeding progeny lines arranging from F2 to F7 are being grown in Dawson, GA and Headland, AL for selection of tomato spotted wilt virus (TSWV) resistance and drought tolerance. Thirty-eight advanced lines have been tested at four locations in GA, AL and MS for yield and disease trials. The F1 seeds from the cross between ‘C76-16’ and ‘Georgia Green’, two lines indentified as drought tolerant germplasms with different drought tolerant mechanisms, were grown in the field in 2012. F2 progenies will be used to prove our hypotheses and eventually to breed a new line with genes stacked. New crosses that relate to drought tolerance were also made in greenhouse in 2012. A set of high oleic peanut genotypes is grown in Headland, AL in 2012 for testing the effects of alleles in controlling oleic acids. A new trait of high oil content in peanut was also introduced into the breeding program in 2012.


4.Accomplishments
1. New variety of peanut released. New Virginia-type peanut ‘AU-1101’ (Reg. No. CV-xxx, PI 661498), was released in 2011. AU-1101 has an alternate branching pattern, a prostrate growth habit, and high percentage of fancy pods and large virginia-type seeds. It has high yield and medium maturity, uniform pod size and shape, high grade, superior shelling characters, low oil content, normal oleic acid content, and good flavor. AU-1101 was developed through pedigree selection in West Texas and it adapts to West Texas. Fifty acres of AU-1101 were planted as foundation seeds in 2012 and certified seeds will be available for farmers in 2013. The paper ‘Registration of ‘AU-1101’ peanut’ will be published in Journal of Plant Registrations in 2012.

2. Integrated genetic linkage map of cultivated peanut constructed. An integrated genetic linkage map of cultivated peanut was constructed from two recombinant inbred lines (RIL) populations and two quality trait loci (QTLs) underlying TSWV (tomato spotted wilt virus) resistance were identified. The map included a total of 324 markers in 21 linkage maps and it covered 1352 cM genetic distance. This map may serve as a reference map for peanut genome sequencing assembling. The markers underlying two TSWV QTLs could be used in peanut breeding for selection for TSWV resistance. This work will facilitate quantitative trait locus (QTL) analysis and the development of tools for marker assisted breeding in peanuts.

3. The affect of seed dormancy in agricultural production. Seed dormancy is a naturally important biological process which can affect planting, germinating and harvesting in agricultural production. Variability in seed dormancy within the U.S. peanut mini-core was determined. The botanical variety of hypogaea was more dormant than other three botanical varieties. However, significant variability was also identified within the botanical varieties. The accessions identified with more dormancy within the same botanical varieties will be good genetic materials to use in breeding programs for preventing preharvesting sprouts.


Review Publications
Wang, M.L., Chen, C.Y., Pinnow, D.L., Barkley, N.L., Pittman, R.N., Lamb, M.C., Pederson, G.A. 2012. Seed dormancy variability in the U.S. peanut mini-core collection. Research Journal of Seed Science. 5:84-95.

Last Modified: 11/21/2014
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