Exogenous application of moringa leaf extract modulates the antioxidant enzyme system to improve wheat performance under saline conditions

Amongst naturally occurring plant growth stimulants, moringa (Moringa oleifera Lam.) has attained enormous attention being rich in cytokinin, antioxidants and macro-micro nutrients in its leaves. In this study, potential of foliar applied moringa leaf extract (MLE; 30 times diluted), benzyl amino purine (BAP; 50 mg L^-1) and hydrogen peroxide (H₂O₂; 120 μM) at tillering, jointing, booting and heading growth stages was evaluated to induce salt resistance in wheat. Water spray treatment was taken as control. Wheat cv. Sehar-2006 was grown under normal (4 dS m^-1), medium (8 dS m^-1) and high (12 dS m^-1) soil saline conditions. Application of these stimulants decreased the shoot Na⁺ and Cl^- contents, with simultaneous increase in shoot K⁺ contents. Maximum shoot K⁺ (48. 62 %) contents were recorded with MLE application under high salinity. Activities of leaf antioxidants viz. superoxide dismutase, peroxidase and contents of total soluble phenolics were increased at medium salinity level; whereas ascorbate contents were also improved by MLE application at high salinity level. However, maximum increase in leaf total soluble protein (35. 9 %) was observed with BAP application at medium salinity. The shoot length, shoot and root dry weights were decreased with increase in level of salt stress. Grain weight (18. 5 %) and kernel yield (18. 5 %) were also improved by MLE application under saline and normal conditions than other stimulators used. In conclusion, foliar applied moringa leaf extract could ameliorate salinity-induced adverse effects by activation of antioxidant defense system and decrease in accumulation of Na⁺ and Cl^- into shoots under moderate saline conditions.