Assessing Mercury-Induced Stress on two Commonly Cultivated Mung Bean (Vigna radiata) Varieties: Evaluating its Effect on the Seed Germination and Seedling Growth

Abstract

Mung bean (Vigna radiata L.), also known as green gram, is a short-season summer legume widely grown in tropical and subtropical regions, particularly in countries like Pakistan, China, India, Thailand, Indonesia, and the Philippines. Despite its agricultural importance, little is known about its response to mercury (Hg) stress. This study evaluated the biochemical and physiological effects of varying Hg concentrations (0, 50, 100, 150, 250, and 350 mg/kg) on two mung bean varieties, NM-06 and AZRI-06. Key growth parameters such as shoot and root length, as well as biomass, were measured to assess the impact of Hg during germination and growth. Results showed a dose-dependent decline in plant growth and biomass. Nutrient content in leaves was also affected: levels of carbon, nitrogen, phosphorus, potassium, and magnesium decreased, while sodium increased. Photosynthetic rate, chlorophyll, protein, and proline levels were significantly reduced under Hg stress. Yield components were adversely impacted, with the greatest effects observed in pod number and seed weight. A maximum harvest index of 8% was recorded. AZRI-06 showed greater tolerance to Hg than NM-06. Higher Hg doses (250–350 mg/kg) caused more severe damage compared to lower doses. The findings indicate that Hg stress negatively affects mung bean morphology, physiology, and yield. Further research is needed to understand the underlying stress-response mechanisms in germinating seeds.