Silicon-mediated Improvement of Drought Tolerance in Two Wheat Genotypes

DROUGHT is an abiotic stress that affects agriculture and annually causes major setbacks to agricultural productivity. Silicon (Si), a plentiful component of soil which is found to play a role in the alleviation of plant drought stress in plants. Wheat cultivars Suds 14 and Sakha 95 were subjected to drought stress by withholding water at 11 days after emergence (DAE) and amended with 2 mM Na2SiO3 either as soil or foliar applications. So, the treatments were: control, control + Si (as soil application), control + Si (as foliar spray), drought, drought + Si (as soil application), and drought + Si (as foliar spray). The results revealed that drought negatively affected the growth, morphological characteristics, and some metabolic activities of the two wheat genotypes by decreasing most of the measured parameters compared to their control values. Sakha 95 was found to be more sensitive to drought than Suds 14. Both Si treatments improved the drought tolerance in both cultivars however, soil application was more effective than foliar spray in alleviating drought stress in both wheat genotypes. Suds 14 was the most responsive genotype in terms of the morphological traits such as root length, shoot length, and root: shoot ratio. Furthermore, the Si treatment preserved high levels of fresh and dry weights, maintained membrane stability, prevented pigment degradation, increased the accumulation of total soluble and insoluble sugars, enhanced protein, proline, total amino acids, and glycine betaine contents, and promoted the activity of antioxidant enzymes compared to the stressed non-amended plants.