Assessing the usefulness of Moringa oleifera leaf extract and zeatin as a biostimulant in enhancing growth, phytohormones, antioxidant enzymes and osmoprotectants of wheat plant under salinity stress

Salt stress is a main constituent of environmental stresses which causes a deterioration in crop development and yield. Fortunately, using leaves extract as Moringa oleifera leaf extract and zeatin have a real influence on lessening the harmful impacts of salt on crops. Two greenhouse studies were done in a complete randomized design with three levels of either Moringa oleifera leaf (MLE) extract or zeatin being applied to wheat plants without stress (0.23 dS m-1) or with salinity stress (6.25 dS m-1). Salinity led to increases in the contents of endogenous abscisic acid (ABA), total soluble sugars TSS and proline, malonaldialdehyde and hydrogen peroxide contents in addition to increasing antioxidant enzymes activities (peroxidase POX, superoxide dismutase SOD and catalase CAT). Moreover, salinity stress decreased the growth parameters, chlorophyll content and yield attributes of wheat plants. However, the foliar application of MLE (10% and 20%) and zeatin (200 and 400 mg L-1) improved the growth of wheat plants under both normal and salt-stressed conditions through increasing endogenous phytohormones (IAA, GA3 and zeatin), photosynthetic pigments, total soluble sugars and proline contents. Furthermore, the applicants further increased the activities of antioxidant enzymes beside the non-enzymatic antioxidants phenolic compounds and antioxidant activity (DPPH%) which participate in reducing the excess accumulation of free radicals (ROS). It is clear that the use of MLE and zeatin supports the salinity tolerance of wheat plants. Moringa oleifera leaf extract and zeatin are viable alternatives for optimizing agricultural production and enhancing plant tolerance in arid and semi-arid regions.