Abstract

Salinity is major abiotic stress limiting plant growth worldwide. Plant adaptation to salinity stress involves diverse physiological and metabolic pathways. In this study, we assessed the effects of foliar application of zinc oxide nanoparticles (ZnONPs) and Moringa leaf extract (MLE) on salt tolerance in faba beans (cultivar, Sakha 4). Morphological, chemical, and biochemical parameters of plants grown under saline condition (50 and 100 mM NaCl) were assessed 60 days after sowing. Salt stress caused a remarkable reduction in growth traits, photosynthetic pigments, proline, minerals, total phenol, and enzyme activity of the faba bean variety. The results showed that foliar spraying of MLE and ZnONPs on faba bean grown under salt-stressed conditions promoted growth parameters (that is, shoot length, numbers of leaves, relative water content, shoot, roots fresh and dry weights), photosynthetic pigments (that is, chl a, b, total chlorophyll and carotenoids), proline, mineral elements (Na⁺, K⁺, Ca⁺², and Zn⁺²), total phenol and enzyme activity (POX, PPO, APX, and CAT) compared to control plants. Based on these findings, the potential of foliar spraying application of MLE and ZnONPs may help alleviate the negative effect of salinity on growth, photosynthesis efficiency, and biochemical properties of faba bean.

Key words: Faba bean, Moringa oleifera, antioxidant enzyme activity, ZnO nanoparticles, salt stress, proline.