APPLICATION OF MORINGA OLEIFERA PLANT EXTRACTS FOR ENHANCING THE CONCENTRATION OF PHOTOSYNTHETIC PIGMENTS LEADING TO STABLE PHOTOSYNTHESIS UNDER HEAT STRESS IN MAIZE (ZEA MAYS L.)

The research experiment was conducted to know the photosynthetic parameters in maize plants exposed to high temperature after applying different methods and types of extracts of Moringa oleifera for mitigating heat stress. Two maize hybrid varieties namely SB-11 (heat tolerant) and ICI-984 (heat sensitive) raised under control (ambient temperature 25 degrees C) and high temperature (35 degrees C) conditions. To lessen the effect of thermal stress, these hybrid maize plants were exposed to exogenously application of aqueous leaf (fresh and shade dried) and flower extracts of M. oleifera using 3 methods such as seed priming, foliar spray and medium supplementation. The data regarding various photosynthetic pigment parameters like chlorophyll a, chlorophyll b, carotenoids and their ratios were recorded. The results depicted that foliar application of M. oleifera extracts was the most effective in increasing the amount of chlorophyll a, chlorophyll b and carotenoid contents and soil application of moringa extract was more favorable towards enhancing total chlorophyll pigments. Moringa oleifera dry leaves extract (MDLE) applied through foliar application and medium supplementation modes was the most effective in improving the photosynthetic pigments in heat tolerant hybrid under heat stress. Thus increased accumulation of chlorophyll a, chlorophyll b and reduced chlorophyll-to-carotenoids ratio shown by SB-11 (a heat tolerant maize hybrid) resulted in enhancing photosynthetic pigments leading directly to more photosynthesis and indirectly to the heat tolerance. This study would be helpful in alleviating the adverse effects of heat on photosynthetic machinery and thus increasing the yield of maize under heat stress.