Moringa leaf extract as biostimulant improves water use efficiency, physio-biochemical attributes of squash plants under deficit irrigation

Natural plant growth biostimulants are intensively used nowadays for plant growing in normal and adverse conditions. Severely affected by salt and drought stresses, squash (Cucurbita pepo L.) is an important vegetable crop that highly ranked in economic importance worldwide. The current study aimed to evaluate whether leaf extract of Moringa oleifera (MLE), as a novel natural biostimulant for plant growth, could play a role in improving drought tolerance in squash plants under saline condition. In summer and fall seasons of 2016, MLE (3%) was foliar sprayed for plants under full (100% of ETc) or deficit irrigation (DI; 80 or 60% of ETc). The effect of MLE on the growth, yield characteristics and water use efficiency (WUE), physio-biochemical attributes, and leaf anatomy of squash plants exposed to DI stress was assessed. MLE-treated plants exposed to DI had higher growth and yield characteristics, harvest index (HI),WUE, chlorophyll fluorescence (Fv/Fm and PI), photosynthetic pigments, soluble sugars and free proline, leaf anatomy, relative water content (RWC%) and membrane stability index (MSI%) and had lower electrolyte leakage (EL%) compared to MLE-untreated plants. Application of 3% MLE was effective in alleviating damages of drought stresses in squash plants by maintaining higher RWC, WUE, and osmoprotectants, and lower EL.