Mitigation of Cadmium Stress by Salicylic Acid: Physiological and Biochemical Responses in NM-2006, NM-92, and Mash-88 Mung Bean Varieties

Cadmium (Cd) is a major environmental pollutant that adversely affects plant growth and productivity, creating a need for effective mitigation strategies. This study aims to evaluate the impact of salicylic acid (SA) priming on the physio-biochemical characteristics of three mung bean varieties (Vigna radiata L.), namely NM-2006, NM-92, and Mash-88, under Cd stress. To achieve this, the mung bean varieties were subjected to Cd stress with and without SA priming, and their growth, chlorophyll content, protein levels, and oxidative stress markers were analyzed. Results showed significant reductions in growth, chlorophyll, and protein contents, alongside increased oxidative stress markers such as hydrogen peroxide and malondialdehyde under Cd stress. Moreover, Cd exposure also led to higher levels of proline, glycine betaine, and total soluble sugars. However, SA priming alleviated these adverse effects by enhancing growth, chlorophyll fluorescence, and protein content while reducing oxidative damage by upregulating the enzymatic antioxidant mechanism. Additionally, SA priming also modulated phytohormone levels, specifically increasing abscisic acid and jasmonic acid while decreasing ethylene. Comparative analysis revealed that NM-2006 suffered the most from Cd stress, NM-92 showed a better response to SA priming, and Mash-88 exhibited the least damage and greatest benefit from SA priming. These findings suggest that SA is an effective protective agent that enhances stress tolerance in mung bean varieties, offering valuable insights for improving crop resilience in contaminated environments.