Variability for drought resistance related traits in the mini core collection of peanut

Peanut (Arachis hypogaea L.) productivity is low in the semiarid tropics mainly because of drought caused by low and erratic rainfall. Identification of genotypes that have a greater ability to use limited available water is important to enhance productivity of the crop. Water-use efficiency (WUE) is correlated with specific leaf area (SLA) and soil plant analysis development (SPAD) chlorophyll meter reading (SCMR) and both have been suggested as surrogate traits for selecting for WUE in peanut. The present study was conducted to: (i) identify genotypes with high WUE using SLA or SCMR and (ii) evaluate relationship between and relative stability of SCMR and SLA in these genotypes. The 184 mini core entries, consisting of 37 fastigiata, 58 vulgaris, 85 hypogaea, two peruviana, and one each of aequitoriana and hirsuta and four control cultivars, M 13, Gangapuri, ICGS 44 and ICGS 76 were evaluated for SLA, SCMR, and 19 vegetative, reproductive, and quality traits in the 2001 rainy and 2001-2002 postrainy seasons at ICRISAT Center. Data were analyzed by REML analysis. Seasons were significant for all traits. Variances due to genotypes were significant for SCMR and SLA at 60 and 80 d after sowing (DAS) and other traits except pods per plant, yield per plant, haulm yield per plot, and protein and oil contents. The genotype x season interactions were significant for both SCMR and SLA at 80 DAS only and for all other quantitative traits except number of primary branches, and pod width. The SCMR values at different stages and seasons were more positively correlated with each other than the correlation of SLA values together. SCMR and SLA were negatively correlated. SCMR values were more strongly correlated with pod yield and other economic traits such as 100-seed weight at both 60 and 80 DAS than SLA. On the basis of higher heritability and lower proportion of genotype x season interaction variance to phenotypic variance, SCMR appeared to be more stable than SLA. On the basis of SLA and SCMR values compared with the control cultivar, five vulgaris and 13 hypogaea accessions were selected. These accessions and control cultivars were grouped by scores of the first 15 principal components (PCs). The clustering by UPGMA method indicated that the selected accessions were diverse from the control cultivars and can be used in the peanut improvement programs to develop cultivars with a broad genetic base.