@article{icrisat3129,
            year = {1994},
           title = {Water-use efficiency and carbon isotope discrimination in peanut under water deficit conditions},
          volume = {34},
          number = {1},
           pages = {92--97},
          author = {G C Wright and R C Nageswara Rao and G D Farquhar},
       publisher = {Crop Science Society of America},
         journal = {Crop Science},
             url = {http://oar.icrisat.org/3129/},
        abstract = {Because of its relationship with water-use efficiency (W), carbon isotope discrimination in leaves ({\ensuremath{\Delta}}) was proposed to be useful for identifying genotypes with greater water-use efficiency. In this study we examined the relationship between W and {\ensuremath{\Delta}} in four peanut (Arachis hypogaea L.) genotypes. The genotypes were grown in and around mini-lysimeters embedded in soil and were subjected to two drought regimes, intermittent and prolonged water deficit conditions, by varying the irrigation timing and amount. Automated rain-out shelters prevented any rain from reaching the experimental plots during the treatment period. The mini-lysimeters allowed accurate measurement of water use and total dry matter (including roots) in a canopy environment. Water-use efficiency, which ranged from 1.81 to 3.15 g kg?1, was negatively correlated with {\ensuremath{\Delta}}, which ranged from 19.1 to 21.8\%. Tifton-8 had the highest W (3.15 g kg?1) and Chico the lowest (1.81 g kg?1, representing a variation in W of 74\% among genotypes. Variation in W arose mainly from genotypic differences in total dry matter production rather than from differences in water use. It is concluded that {\ensuremath{\delta}} is a useful trait for selecting genotypes of peanut with improved W under drought conditions in the field. A strong negative relationship existed between W and specific leaf area (SLA, cm3 g?1) and between {\ensuremath{\Delta}} and SLA, indicating that genotypes with thicker leaves had greater W. SLA could therefore be used as a rapid and inexpensive selection index for high W in peanut where mass spectrometry facilities are not available.

}
}