Evaluation of Grain Yield-Based Drought Tolerance Indices for Screening Durum Wheat Genotypes = تقييم محصول الحبوب بالنسبة لمؤشرات تحمل الجفاف لفحص الأصناف الوراثية في القمح القاسي

Abstract

Among the different environmental stresses, drought is the main constraint that has negative effect on crop production. The objective of this study was to evaluate seven drought tolerance indices, namely the stress susceptibility index (SSI), tolerance index (TOL), yield stability index (YSI), yield index (YI), mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI), to be used in screening drought tolerant durum wheat (Triticum durum) genotypes. For this purpose, 50 genotypes were studied in a randomized complete block design with three replications under irrigated and rainfed conditions during 2013–2014 growing season. The drought tolerance indices were calculated based on grain yield under irrigated (Yp) and rainfed (Ys) conditions. Results of combined analysis of variance showed the significant influences of drought stress on all studied traits except number of total and productive tillers per plant, as well as significant differences among genotypes for all studied traits. Results of correlation analysis showed that GMP, MP and STI indices were able to discriminate between drought-sensitive and drought-tolerant durum wheat genotypes. Based on Principal Component Analysis (PCA) and biplot analysis, genotypes G1, G10, G29 and G41 were identified as drought tolerant while, G13, G21, G23 and G25 were identified as drought sensitive genotypes. Cluster analysis using grain yield under irrigated (Yp) and rainfed (Ys) conditions and drought-tolerance indices divided the 50 genotypes into five groups, therefore this result was consistence with results of biplot analysis.