Abstract
Phaseolus vulgaris (L.) is cadmium (Cd2+)-sensitive crop that needs an exogenous support to grow well under Cd2+ stress. Therefore, it was grown in the presence of 1 mM Cd2+ beginning from 15 days after sowing (DAS) and was foliar-sprayed with Moringa oleifera leaf extract nanoparticles (n-MLE) in comparison to traditional extract (t-MLE) at 20 and 30 DAS. Plants were sampled for growth, physio-biochemical, antioxidant analysis, and yield. The optimized levels of 2 and 6% of n-MLE and t-MLE, respectively from the preliminary study were used. Growth and yield attributes, levels of leaf chlorophylls and carotenoids, plant water use efficiency (WUE), photosynthesis efficiency in terms of PI and Fv/Fm, cellular relative water content (RWC) and cellular membrane stability (MSI) were significantly decreased. In contrast, Cd2+ content in different plant parts, ion leakage (EL), peroxidation of lipids (MDA content), content of hydrogen peroxide (H2O2), free proline, soluble sugars, alpha-tocopherol (alpha TOC), glutathione (GSH), ascorbic acid (AsA), and activity of glutathione peroxidase (GPX), ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD) were markedly elevated with exposing plants to Cd2+ stress compared with the corresponding control. However, foliar spray with n-MLE or t-MLE considerably detoxified the Cd2+ stress effects and significantly improved the abovementioned parameters by significantly increasing growth and yield attributes, photosynthetic pigment levels, Fv/Fm, PI, WUE, RWC, and MSI, and further elevating the levels of alpha TOC, free proline, soluble sugars, AsA, GSH, and the activities of SOD, CAT, APX, GPX. In contrast, Cd2+, EL, MDA and H2O2 contents were markedly reduced compared to the corresponding controls. In comparison to t-MLE, n-MLE was more effective treatment that is recommended to use for ameliorating the harmful effects of Cd2+ stress up to the level of 1 mM. (C) 2020 Friends Science Publishers