Mitigation of Salinity Stress in Vicia faba by Natural and Synthetic Growth Enhancers
Authors: Helal Ragab Moussa , Mohamed Abd El-Fattah Hassan Mohamed
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Soil salinity decreases plant growth, photosynthetic activity and productivity besides resulting in nutrient imbalance in plants. Coping with salinity is a global issue to ensure sustainable crop production. This study evaluated the efficacy of foliar applied growth enhancers, Moringa oleifera leaf extract (MLE; 20 times diluted), amongst naturally occurring plant growth stimulants, and for evaluating the efficacy of sulphate of potash as a source of potassium (SOP, 3%) in reducing the salinity effects in faba bean plants. The experiment was conducted with two levels of salinity in the nutrient solution, 0.0 (Control) and 135 mM of NaCl (S) which are equivalent to13 dS m-1 . Water spray treatment was taken as a control. The plants grown at 13 dS m-1 show a decreased in the chlorophyll (a+b), carotenoids, total protein contents, weight of 100 grains, enzyme activity of ribulose-1,5-bisphosphate-carboxylase/oxygenase (RuBPCase), photosynthetic activity ( 14CO2-fixation) and macronutrient level (N, P, and K) in shoot and root. Foliar application of MLE+S and SOP+S increased these parameters as compared to salt stressed plants. In contrast, salt stressed faba bean plant considerably increased proline content, Na+ and Clˉ levels and transpiration rate as compared to control and plants treated with MLE+S and SOP+S. Meanwhile, foliar application of MLE+S and SOP+S decreased Na+ and Clˉ levels and proline content below that of the control plants. Foliar applied growth enhancers (MLE+S and SOP+S) increased the macronutrient contents N, P, and K in shoot and root of faba bean plants as compared to salt stressed and control plants. Nonetheless, foliar applied growth enhancers particularly moringa leaf extracts (MLE) and sulphate of potash as a source of potassium (SOP, 2%), ameliorated the adverse effects of salinity stress by enhancing carboxylating enzyme activity of RuBPCase, total protein level, macronutrient contents (N, P, and K), photosynthetic activity (14CO2-assimilation), total yield and plant secondary metabolites. Moringa leaf extract was more effective than sulphate of potash.