Wheat Drought Tolerance: Morpho-Physiological Criteria, Stress Indexes, and Yield Responses in Newly Sand Soils

Drought presents a major risk to wheat growth and productivity under changing climates. During the last few years, various morphological and physiological approaches were used to overcome drought stress-associated problems. Cultivation of tolerant wheat cultivars can serve as a sustainable choice to raise wheat yield under water stress. Herein, field trials were carried out at the experimental farm of Ismailia Agricultural Research Station, Egypt, in two successive growing seasons (2020/2021 and 2021/2022) to investigate the response of four Egyptian bread wheat cultivars (Misr 1, Misr 3, Giza 171, and Sakha 95) to drought stress according to morpho-physiological characteristics, yield, and stress indices. Irrigation treatments and cultivars were assigned to the main and sub-plots, consequently, in a split-plot design with three replicates. The findings revealed that in both the first and second seasons, drought drastically revoked growth vigor of shoot, growth vigor of flag leaf, relative water content (%), membrane stability index (%), photosynthetic pigments, heading (days), maturity (days), as well as yield and yield attributes: spike length, number of spikes/m(2), spike weight, grain number/spike, 100-kernel weight, grain yield/m(2), straw yield/m(2), biological yield/m(2), and harvest index of all four wheat cultivars. Conversely, drought caused a marked increase in saturation water deficit (%), carotenoids content, and NKP uptake of all four wheat cultivars in both study seasons. The current study found that all four of the wheat cultivars were drought-tolerant plants. These cultivars exhibited similar drought-tolerant behaviors, which included decreased loss in relative water content, membrane stability, and photosynthetic pigment levels, consequently reducing wheat grain yield loss under water stress. Additionally, the drought tolerance indices of Sakha 95 > Giza 171 > Misr 1 > Misr 3 were revealed by the stress sensitivity index (SSI), mean productivity (MP), stress tolerance index (STI), and yield stability index (YSI). In conclusion, Misr 3 was the least tolerant wheat cultivar and Sakha 95 was the most tolerant. These results can be applied to breeding programs by plant breeders.