Modulation of morpho-physiological responses and antioxidant enzymes in green gram under metal stress
摘要
The ecological health status of our planet has gradually declined, with industrialization being a key cause of environmental degradation. The massive number of industries producing more waste materials with or without recommended treatment and improper management ultimately accumulates, which affects ecosystems directly or indirectly. Among the most common contaminants, heavy metals, particularly lead (Pb), are associated with soil fertility loss, water and air pollution, which poses enormous risks to life of biodiversiy. In the current study we aimed to analyze the emerging metal pollution in soil and its impact of metal (lead) to green gram [Vigna radiata (L.) Wilczek] through, seed germination, growth characters, physio-biochemical changes, photosynthetic rate, stomatal conductance and antioxidant systems. Although no significant differences in seed germination were noted within treatments, Pb exposure (100–400 μM) influenced growth and physiological responses in Vigna radiata. Shoot length increased from 17.96 cm in the control to 21.38 cm at 400 μM, while root length increased from 11.25 to 14.60 cm. However, photosynthetic pigments declined under Pb stress, with total chlorophyll decreasing from 38.08 mg (control) to 23.56 mg g−1 FW at 300 μM, and carotenoids showing a significant reduction at the same concentration. In contrast, anthocyanin content increased markedly, reaching 3.5 and 4.7 mg g−1 FW at 300 and 400 μM, respectively. Antioxidant profiling revealed a decline in SOD activity (983.08 to 905.73 U g−1 FW) and CAT activity, whereas POD increased from 4.8 to 9.3 mM g−1 FW and APX from 253.39 to 296.9 mM g−1 FW at higher Pb concentrations, indicating activation of specific defense mechanisms against oxidative stress. ICP–MS analysis further showed predominant Pb accumulation in roots (0.358 μmol g−1 DW at 300 μM), with comparatively lower levels in stems and leaves, suggesting restricted translocation to aerial tissues. This study sheds light on the tolerance and adaptive mechanisms of V. radiata under lead stress, highlighting its potential for phytoremediation and the importance of managing industrial waste to protect environmental and human health.