Protective Role of Silicon (Si) Against Combined Stress of Salinity and Boron (B) Toxicity by Improving Antioxidant Enzymes Activity in Rice

Farooq MA, Saqib ZA, Akhtar J, Bakhat HF, Pasala R-K, Dietz K-J. Protective Role of Silicon (Si) Against Combined Stress of Salinity and Boron (B) Toxicity by Improving Antioxidant Enzymes Activity in Rice. SILICON. 2019;11(4):2193-2197.The beneficial element silicon (Si) is known to enhance plant tolerance against various kinds of biotic and abiotic stresses. However, little is known about its protective role for plants facing multiple stresses such as salinity and boron (B) toxicity. Therefore, the current study was planned in pots to evaluate the beneficial role of exogenous applied Si (150 mg kg(-1)) nutrition against salinity stress (10 dS m(-1)), and B toxicity (2.5 mg kg(-1)) alone or in combinations. Results showed that both salinity and B toxicity reduced plant growth and biomass of rice, with maximum damage under their combined stress due to increased uptake of toxic ions such as sodium (Na+) and B. Contrarily, Si application helped the plants to overcome negative effects of these toxic ions by increasing silica and K+ uptake and decreasing Na+ and B entry in plants that ultimately lead to improvement in plant biomass. High silica uptake ability of rice significantly improved the efficiency of antioxidant mechanism, as indicated by reduced catalase (CAT) activity and improvement in guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activity by Si application under stress, resulting in reduced oxidative damage. From this study, we conclude that Si fertilization can enhance crop production in salt affected soils by helping plant defenses against salts as well as associated B toxicities; however, field trials should be carried out before setting any recommendations for farmers