Exogenous osmolytes supplementation improves the physiological characteristics, antioxidant enzymatic activity and lipid peroxidation alleviation in drought-stressed soybean

Soybean is considered among the crops that demand a plentiful water supply, particularly during the growth phase to achieve maximum production. The drought stress adversely reduces the productivity and yield of soybean as compared to other legumes crops. With the passage of time, the local varieties of soybean have declined their yield potential because they have no resistance against abiotic stresses. There is a need to explore the avenues that minimize the impact of drought on soybean plants. In this regard, a pot experiment was performed to assess the exogenously applied foliar supplementation of proline and glycine betaine osmolytes @10mM and 20mM on the various physical parameters, oxidative stress amelioration, and cessation of damaging lipid peroxidation that indicates the beneficial effects of osmolytes supplementation in drought-stressed soybean. The water stress was applied at 50% of field capacity sown with three different genotypes of soybean including Ajmeri, Rawal, and Faisal-Soy. This leads to the reduced morphological growth and physiological response in all three soybean genotypes in lieu of water stress conditions. The water stress also reduced the content of proline and glycine betaine and reduced the activity of antioxidant enzymes. It also enhanced the process of lipid peroxidation in all genotypes of soybean. The osmolyte treatments enhanced the resistance against drought stress conditions by improving the physiological response and antioxidant enzymatic activity. It also decreased the degree of lipid peroxidation evaluated through MDA and H2O2 contents. The most significant results were found in the Ajmeri genotype as compared to other genotypes at 20mM foliar application of proline. Therefore, it is suggested that the use of exogenous osmolytes especially proline is helpful in enhancing soybean production and alleviating the drought stress effects.