Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2006
Publication Date: 8/15/2006
Citation: Rowland, D., Lamb, M.C. 2006. The effect of irrigation and genotype on carbon and nitrogen isotope composition in peanut (arachis hypogaea l.) leaf tissue . Peanut Science.
Interpretive Summary: : Water-use efficiency in agriculture is becoming more important for both environmental and economic reasons. Peanut producers rely on irrigation to increase yields, but by growing water-use efficient varieties, they can increase yields in drier environments. This study quantified the amount of variation in water-use efficiency and other related leaf traits among different peanut varieties grown under different levels of irrigation. There was significant variation among peanut varieties in water-use efficiency but it was not affected by the irrigation environment. That means that there is a sufficient amount of variation in peanut water-use efficiency that can be used in breeding programs aimed at developing new varieties that have high water-use efficiency. Without a significant response to irrigation, it appears that the water-use efficiency trait is strongly genetically controlled and is not greatly affected by the amount of irrigation received by the crop. Overall, the variety AT201 appeared to perform the best under water limitation, while the variety Georgia Green was lowest in water-use efficiency.
Technical Abstract: Water scarcity is a significant problem faced by producers worldwide and is becoming an increasing problem to growers in the U.S. peanut (Arachis hypogaea L.) producing areas due to years of drought and increasing urban demands on water resources. Because of this, high water-use efficiency (WUE) has now become a priority in many peanut breeding programs. To support this effort, the variation in WUE, as measured by carbon isotope composition ('13C), of three commonly grown peanut cultivars was evaluated under differing irrigation environments during 2001 and 2002 at a research farm in Shellman, GA, U.S.A. The specific experimental objectives were: 1) to determine if genetic variability existed in '13C, and '15N SLA, SPAD among three commonly grown U.S. peanut genotypes; 2) to determine if differing irrigation levels affected the pattern of variability; and 3) to quantify the relationship between '13C and the measured leaf phenotypic characteristics. During both 2001 and 2002, cv. Georgia Green had significantly higher yields and lower '13C and SPAD chlorophyll content than the other two genotypes, and lower %N than the cultivar C99R. Specific leaf area and %C for Georgia Green were significantly greater than for the cultivar AT201. In addition, irrigation treatment significantly affected yield such that the NI treatment yields were significantly lower than any of the irrigated treatments (33%, 66%, or 100%). However, the irrigation effects on leaf phenotypic characteristics were less apparent with differences existing only for '15N, SPAD chlorophyll, and SLA. The correlation of '13C and yield was significant for C99R in 2001 and AT201 in 2002, while correlations with '13C and the other leaf phenotypic characteristics were scarce. This makes the utility of the traits as easily measured surrogates for WUE very limited.