ROLE OF MELATONIN FOLIAR APPLICATION IN ALLEVIATING HAZARDS OF WATER DEFICIT ON RED KIDNEY BEAN PLANTS GROWN UNDER N FIXATION STIMULANTS

Maximization of crops production under stress conditions (drought...etc.) is the main target for all countries including Egypt. A little is known about the joint effects of nutrients stimulating N2 fixation under water stress. So, field research trial was executed during the season of 2021 as the sake of studying different regimes of irrigation as main plots i.e., irrigation with 50 m3 water fed-1 which represented the followed irrigation and irrigation with 37.5 and 25 m3 water fed-1 which represented the water deficit, addition of some solutions as subplots [ without (control treatment), Mo, Co, Cu, Co+ Mo, Co+ Cu and Mo+Cu at rate of 10 mg L-1 for all] and exogenous application of melatonin (with or not ) at rate of 1.0mmol L-1 as sub-subplots on the performance of red kidney bean plants. The findings showed that plants irrigated with 37.5 and 25 m3 water fed-1 possessed a low performance and cumulative yield compared to red kidney bean plants irrigated with 50 m3 water fed-1. Also, molybdenum, cobalt and copper solutions (either alone or in combination) improved nodulation nitrogenase activity and No. of nodules plant-1compared to plants untreated, thus these treatments positively reflected on all studied growth criteria, pods yield and its components, where the superior treatment was Co plus Mo as combined treatment. The exogenous application of melatonin improved the tolerance of plants to water deficit comparing with untreated plants. Also, water deficit stress (37.5 and 25 m3 water fed-1) caused raising production of enzymatic antioxidants in plant tissues such as peroxidase and catalase, while solutions addition as well as exogenous application of melatonin led to a decline of the red kidney bean plant's self-production from these enzymatic antioxidants. Available N, P and K of soil after harvest pronouncedly differed as a result of studied treatments.