PERFORMANCE AND ADAPTABILITY OF SOME BREAD WHEAT GENOTYPES FOR WATER STRESS UNDER HIGH TEMPERATURE AT UPPER EGYPT REGION

ABSTRACT Water and heat stress are the major constraints facing wheat improvement in Upper Egypt. High yielding genotypes under stress and non-stress conditions is the key factors for the improvement of wheat production. Thus, two field experiments were carried out in two seasons 2017/2018 and 2018/ 2019. Each experiment evaluates eight genotypes of bread wheat under two irrigation regimes (stress, and Normal). A Split–plot design in randomized complete block with three replications was used. The irrigation regimes were arranged in the main plots, while the eight genotypes were randomly arranged in the subplots. Results revealed that increasing irrigation water had significantly increased yield, and yield components. This increase estimated by 19.28% for grain yield, by 24.54% for number of spikes per square meter, by 14.04% for number of kernels per spike, and by 6.76% for kernels weight as a result of increasing in irrigation water from low to normal. Data showed reduction in grain yield for all genotypes under stress as compared to non-stress condition. This reduction ranged from 16.46% for Shandaweel 1 to 26.72% for line 5. The correlation matrix between grain yield under stress and non-stress conditions and stress tolerance indices revealed that stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), and harmonic mean (HM) could be detected as the most suitable indices for identifying high yielding genotypes in both conditions. Therefore, these indices could be used successfully as selection tools for screening genotypes. Screening water stress tolerant genotypes by using mean rank, standard deviation of ranks and rank sum (RS) distinguished genotypes, Results revealed that ranking of wheat genotypes for indices of class 2 (STI, MP, and GMP) indicated the superiority of Line 3, Line 2, and Line 4. Meanwhile, genotypes varied moderately between indices in class 1. Furthermore, the rank of stress susceptibility index (SSI), yield stability index (YSI), and reduction ratio (YR) obtained the superiority of Shandaweel 1 and Line 2.Cluster analysis showed the genotypes, based on indices tended to group into three groups: tolerant, semi-tolerant and sensitive genotypes. Tolerant group included two genotypes; Line 2 and Line 3 which had the highest values of tolerance indices under stress conditions. Principal component analysis (PCA), indicated that the first and second components justified 99.908% of variations among water stess tolerance indices. Biplot analysis showed significant positive correlation between grain yield in the stress condition (Ys) with indicators GMP, HM, YI, YSI and DI, Thus, they are separating water stress tolerant genotypes. According to all different statistical procedures: Among all genotypes, Giza 171, Shandaweel 1, Line 1, and Misr 2 were identified as the genotype with high and stable yield in stress and non-stress conditions. Thus, they can be considered as a moderate water stress-tolerant genotypes. Meanwhile, Line 3, Line 2, and Line 4 were identified as the most tolerant to water and heat stress. Hence, results indicated the possibility of released and expanding planting of these new advanced lines especially under heat and water stress conditions in Upper Egypt regio