EXPLORING THE POTENTIAL OF MORINGA (Moringa oleifera) LEAF EXTRACT AS NATURAL PLANT GROWTH ENHANCER

Abstract

Among naturally occurring plant growth stimulants, Moringa oleifera has attained enormous attention because of having cytokinin in addition to other growth enhancing compounds like ascorbates, phenolics, other antioxidants along with macro- micro nutrients in its leaves. With these properties, exogenous application of Moringa leaf extract (MLE) was done in wheat, pea and tomato to evaluate its efficacy as crop growth enhancer The objective was to optimize dose, method of exogenous application, enhancement of growth, yield and antioxidant level under normal and abiotic stresses (late sowing, salinity, and drought). The results showed that 30 times diluted MLE priming in wheat under normal conditions was found to be effective. MLE priming improved the seedling emergence rate, speed and early growth and increased level of antioxidants, leaf total soluble protein and chlorophyll contents as compared to MLE10, Hydro priming, On-farm priming and CaCl2 priming. Large number and heavier grains were obtained in plants raised from MLE30 primed seed which resulted in highest grain yield per plant. All the priming treatments gave more yield than non primed control. Foliar spray of MLE caused an increase of 10.73, 6.00, 10.70 and 4.00% in 1000 grain weight, biological yield, grain yield and harvest index respectively, with MLE spray at tillering + jointing + booting + heading. MLE spray only at heading gave 6.84, 3.17, 6.80 and 3.51% more 1000-grain weight, biological yield, grain yield, and harvest index respectively, as compared to control. MLE extended the seasonal leaf area duration (Seasonal LAD) by 9.22 and 6.45 d over control when applied at all growth stages and single spray at heading, respectively. MLE foliar improved salinity tolerance in wheat by improving wheat seedlings vigour, more chlorophyll a and chlorophyll b contents, exclusion of Na+ and Cl- along with accumulation of K+ and larger contents of enzymatic antioxidants (catalase, superoxide dismutase and peroxidase) and non enzymatic antioxidants (ascorbic acid and total phenolic contents) leading to more 100 grain weight as compared to benzylaminpurine (BAP), hydrogen peroxide (H2O2) and control (water spray) under salinity. The water sprayed plants under highest salinity showed maximum accumulation of Na+ and Cl- while largest K+ contents were observed in case of MLE spray under moderate salinity. MLE and BAP application improved leaf total soluble protein and superoxide dismutase (SOD). For non-enzymatic antioxidants (total phenolics and ascorbic acid), MLE was ranked first under moderate salinity. BAP improved number of grains spike-1 but heavier grains were observed under MLE application in moderately saline conditions. These effects of MLE were more apparent under moderate salinity (8dS m-1) as compared to higher salinity (12dS m-1). The water stress caused reduction in growth and grain yield of wheat due to decreased leaf area and reduced chlorophyll a and chlorophyll b contents. However, foliar application of MLE and BAP minimized these effects of drought. MLE application produced more grain yield under moderate and severe water stress as compared to BAP, K+ and control. Moringa leaves being a rich source of β-carotene, protein, vitamin C, calcium and potassium and act as a good source of natural antioxidants such as ascorbic acid, flavonoid, phenolics and carotenoid, so the exogenous applications of MLE improve the antioxidant status and yield of wheat under drought stress. In case of tomato crop foliar application of MLE30 exhibited large number of flowers, more number of fruits as well as heaviest fruits. The foliar application of BAP produced same number of flowers but lighter weight fruits as compared to MLE30. The minimum fruit weight was recorded in case of foliar applied MLE10, MLE0 and control. The effectiveness of MLE as crop growth enhancer might be due to the presence of growth promoting substances. MLE proved a potential growth enhancer in mitigation of abiotic stresses.