Groundnut improvement: Drought stress and water use efficiency of some peanut genotypes grown under newly reclaimed soil

Water deficiency is one of the major environmental constraints, limiting agricultural productivity, and plays the major role in the distribution of plant species across different types of environments. Forty-seven peanut mutant lines were developed by _-radiation mutagenesis of two commercial genotypes (Giza-6 and NC). The yield performance and water use efficiency, of those forty-seven peanut mutant lines and their parents, were evaluated in a field experiment, using split plot arranged in a randomized complete block design, with two replications. Two irrigation treatments (full irrigation and 50% water requirement) were applied in the main plots, and the subplots were devoted for the peanut genotypes. Stress tolerance index (STI), Stress susceptibility index (SSI), Tolerance index (TOL), Mean productivity (MP), and Geometric mean productivity (GMP) have been measured to assess the tolerance of the genotypes toward water stress. Principal component analysis (PCA) of computed drought tolerance indices, of the tested genotypes, classified the groundnut into four distinct clusters ascendingly as follows: (I) below average (16 genotypes); (II) average (parents + 23 genotypes); (III) above average (6 genotypes); and (IV) excellent performing (2 genotypes) in respect to the two different tendencies of drought tolerance indices, where GMP, MP, STI precisely corresponded to same trend. Water use efficiency (WUE) is estimated to determine the finest genotypes performance regarding severe drought deficits. The water stress treatment assorted the WUE response of genotypes from 0.236 kg/m3 to 0.739 kg/m3. Nine genotypes (G37, G12, G36, G27, G49, G42, G25, G35 and G7) have shown superiority over the sophisticated parent (Giza-6) regarding to WUE means in stress and non-stress conditions. STI, GMP, and MP are high positively inter correlated. Although TOL is moderately correlated toward the whole indices, Whereas SSI is negatively correlated with the previous indices, except TOL reported highly correlation with SSI.