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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
2009 Annual Report


1a.Objectives (from AD-416)
Determine the interaction of conservation tillage, fungicide treatments, and peanut cultivars in sub-surface drip irrigation on oil amount and quality.


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 water-use 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 farm experiment to determine the level of drought resistance in different 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: 620 breeding progeny lines arranging from F2 to F7 are being been grown at Dawson, GA; and 320 and 286 breeding lines were planted at Headland, AL and Brownfield, Texas, respectively. Advanced line tests have been conducted at five locations in four states (TX, AL, GA, and MS) with 32 lines in southeastern region and 36 lines in TX. Fifty-four crosses were made in the greenhouse in 2009.


4.Accomplishments
1. Fifteen genotypes including advanced breeding lines and varieties have been evaluated for variability for water-use efficiency in the project “Heritability Estimates for Drought Resistance Related Traits in Cultivated Peanut (Arachis hypogaea L.)”. Two-year data showed that genetic variability of water-use efficiency existed among tested genotypes and heritability for drought resistance related traits ranges from moderate to high that will aim future breeding effort for genetic improvement for drought resistance in peanuts. In addition, one line (Exp13-9,10) with high yield potential and good drought resistance was identified and this line makes a genetic availability of drought resistance for further breeding movement. Information about whether or not genetic variation exists and identification of those genotypes with enhanced water-use efficiency must be made available before further progress can be made in breeding for enhanced water-use efficiency.

2. Peanut is challenged with disease such as spotted wilt caused by tomato spotted wilt virus as well as adverse environmental challenge such as drought. Molecular plant signals are communicated through gene expression such as increasing or decreasing RNA messages. A strategy to “capture” these messages is to produce cDNA libraries that categorize these signals and the genetic codes can be revealed by DNA sequence of these Expressed Sequence Tags (ESTs). A collaborative effort resulted in the sequencing of 17,376 peanut ESTs from leaf tissue. From this 6,888 unique sequences were identified and 856 simple sequence repeats (SSR, potential molecular markers) were discovered. The newly discovered leaf genes and potential markers will provide the peanut research community new tools to further research, to understand peanut biology, and to develop new DNA markers for development of new peanut varieties with disease and drought tolerance.


Review Publications
Guo, B., Chen, X., Hong, Y., Liang, X., Dang, P.M., Brenneman, T., Holbrook Jr, C.C., Culbreath, A. 2009. Analysis of gene expression profiles in leaf tissues of cultivated peanuts and development of EST-SSR markers and gene discovery.International Journal of Plant Genomics 2009:715605, 14 p. DOI:10.1155/2009/715605.

Last Modified: 10/30/2014
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