Evaluation of some Bread Wheat Mutants for Drought Tolerance Indices under Normal and Drought Conditions

Bread wheat, is the stable food in more than 40 countries including Egypt of the world. 22 mutants and 5 check bread wheat cultivars were evaluated in (M5) 2017/2018 and (M6) 2018/2019 generations, in two separate irrigation treatments experiments using flood irrigation methods. In the first irrigation treatment, irrigation was done every 10 days, while the second irrigation treatments, irrigation was followed every 20 days. Objectives of the present investigation were: 1- To determine of high yielding and drought tolerant bread wheat genotypes under non stress and stress conditions. 2 – To evaluate of drought tolerance bread wheat genotypes using drought tolerance indices. According to water stress, over two years genotypes traits for bread wheat were decreased 6.19% in number of days to heading, 6.25% in number of days to maturity, 11.60% in plant height, 8.79% in spike length, 23.27% in number of spikes per m2, 9.94% in number of grains per spike, 5.79% in 1000 kernel weight, 34.62% in grain yield (ardb/fed), 12.99% in biological yield (ton/fed), 24.50% in harvest index (%). The highest grain yield (ardb/fed under non-stress was obtained by mut.1, mut.59, mut.31, mut.11, mut.2, and mut.68. Whereas in stress conditions mut.132, mut.31, mut.11, mut.59, mut.68 and mut.65 gave the highest yield. Data indicated that mutants 31, 132, 11, 59, 58, and 1 had the largest values for MP, GMP, HM, YP, and YS indicating, they might be to the best promising tolerance. Whereas genotypes Yakora, Mut.44 and Gemmeiza11 had the smallest value of MP, GMP and HM were the most susceptible genotypes. Grain yield in stress condition (YS) was significantly and positively correlated with STI (r=0.916**), MP (r= 0.860**), GMP (r= 0.913**), HM (r=0.952**), YI (r=0.996**), YSI (r= 0.594**) and RDI (r= 0.596**) and negatively corrected with Tol (r= -0.236), SSI (r= -0.660**) and SDI (r=-0.594**). Grain yield in non-stress condition (YP) was significantly and positively corrected with STI (r=0.858**), MP (r=0.917**), GMP (r=0.864**), HM (r=0.804**), Tol (r=0.651**), YI (r=0.587**), SSI (r=0.296) and SDI (r=0.302) and negatively corrected with YSI (r=- 0.302) and RDI (r=-0.301). Results reveled that STI, MP, GMP, HM and YI indices were significantly and positively correlated with grain yield under two conditions. Results of cluster analysis for all of the drought tolerance indices showed that 27 bread wheat genotypes were classified into 4 classes. Cluster1 contained sensitivity genotypes (mutants 37, 64, 199, 166, 44, cultivars Sakha94, Sakha93 and Yakora) that had high values of stress susceptibility (SSI) and low values of tolerance indices (STI, MP, GMP, HM, and YI). Cluster 2 contained semi sensitive genotypes (Mut.2, Mut.3, Mut.25, Mut.26, Sids12 and Gm11) were recommended for irrigation conditions and separated into two groups. First group comprised genotypes Mut.2 and Mut.3. Second group contained genotypes Mut.26, Sids12, Mut.25 and Gm11. Meantime, Cluster 3 contained semi tolerant genotypes number Mut.65, Mut.99, Mut.38, Mut.49 and Mut.161 and Cluster 4 contained tolerant genotypes that had low values of stress susceptibility and high value of tolerance indices genotypes Mut.1, Mut.59, Mut.28, Mut.142, Mut.11, Mut.31, and Mut.68. Where, Mut.132 separated only in cluster 4.