Identifying Wheat Stress Tolerant Genotypes Among Some Bread Wheat Accessions Using Different Drought Tolerance Indices تحديد الطرز الوراثية المقاومة للإجهاد في بعض تراکيب قمح الخبز باستخدام مؤشرات تحمل الجفاف المختلفة

Abstract

Thirty-nine genotypes of bread wheat (Triticum aestivum L.) collected from different regions in Egypt and two commercial varieties were used in this study, to estimate the tolerance indices and to establish the drought tolerance in 41 genotypes. Significant genotypes mean squares were detected for all studied traits, except number of spikes per m2 and grain per spike under water stress. Using stress susceptibility index (SSI), genotypes 4, 6, 1, 31, 19, and 24 were classified as highly drought tolerant. According to stress tolerance index (STI), twelve genotypes were the top performer under stressed conditions. Twenty-nine genotypes showed lowest STI values (< 0.10) which implies that these genotypes were highly susceptible to drought. The greater values of yield stability index (YSI) were observed in genotypes 8,39,17,22,28,12,26 and 37. Based on sensitivity drought index (SDI) the six genotypes 4,6,1,31,19 and 24 revealed the highest values and were identified as tolerant under stress conditions. According to drought index (DI). Grain yield under stressed conditions (YS) was significantly and positively correlated with STI and DI. Yield in non-stress condition (YP) was significantly and positively correlated with YS, SSI, STI, SDI, and DI and negatively correlated with YSI. The total variation expressed between the two components was 99.70%. The variable that has the highest PCA1 value and the lowest PC2 was found excellent in screening genotypes under stress and non-stress conditions. Also, genotypes 17 and 37 are the most tolerant genotypes under water stress.