A novel Moringa oleifera leaf extract can mitigate the stress effects of salinity and cadmium in bean (Phaseolus vulgaris L.) plants

Phaseolus vulgaris plants were grown in the presence of NaCl and/or CdCl2 beginning from the second week, sprayed twice with moringa leaf extract (MLE) at 21 and 28 days after sowing (DAS), and were sampled at 35 DAS for growth and chemical analyses and yielded at the end of experiment. Growth traits, level of photosynthetic pigments, green pod yield and pod protein were significantly reduced with exposing the plants to NaCl and/or CdCl2. However, the follow up foliar application with MLE detoxified the stress generated by NaCl and/or CdCl2 and significantly enhanced the aforementioned parameters. Either individual or combined used stresses increased the electrolyte leakage (EL), lipid peroxidation and plant Cd2+ content, and decreased the membrane stability index (MSI) and relative water content (RWC). However, the foliar application of MLE in the absence of the stress improved the MSI and RWC and minimized plant Cd2+ content but could not affect EL and lipid peroxidation. Proline content and the activity of antioxidant enzymes showed a significant increase in response to MLE as well as to NaCl and/or CdCl2 stress.