Abstract

Alkalinity is a major constraint for sorghum production in Egypt. Silicon (Si) has been verified to play an important role in enhancing plant resistance to abiotic stress. In this study, two sorghum (Sorghum bicolor L.) cultivars of Giza 15 (alkalinity sensitive cultivar) and ICSR 92003 (alkalinity tolerant cultivar), were selected to study the effects of exogenous Si application on plant water status, pigments, protein, nucleic acids and carbohydrates contents of sorghum plants under alkalinity stress. In general, alkalinity stress was found to reduce water potential, photosynthetic parameters, protein, nucleic acids and carbohydrates contents in both sorghum cultivars, while Si application enhanced all these physiological parameters in stressed or unstressed sorghum plants in both cultivars. These results suggested that silicon application was useful to increase alkalinity resistance of sorghum through the enhancement of plant water status, pigments, protein, nucleic acids and carbohydrates contents in sorghum plants.