Melatonin alleviates cadmium phytotoxicity through regulation of growth, photosynthesis and antioxidant potential in two pepper genotypes

Abstract Heavy metal contamination has severely hampered worldwide crop productivity. Cadmium (Cd) pollution is one of the most important environmental and agricultural soil challenges facing the world today, and it is mostly caused by human activity. The current research examines the potential effect of melatonin (ME) in alleviating Cd toxicity in pepper (Capsicum annuum L) seedlings. Cd stress reduced the growth traits, pigments molecules, and gas exchange elements, but increased phenolic content, hydrogen peroxide (H2O2), malondialdehyde (MDA) content and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). Conversely, exogenously applied ME promoted growth characteristics, chlorophyll content, and leaf gas exchange parameters in treated seedlings. Furthermore, ME supplementation further enhanced protein, total phenolics, and antioxidant enzyme activity. The increased activity of antioxidant scavengers played a central role in reducing H2O2 and MDA content in seedlings under Cd toxicity. According to the present research, seedlings pretreatment with ME decreases Cd-toxicity and allows pepper to grow in Cd-contaminated environments. Future research may aid in the understanding of the ME-assisted stress reduction mechanism in pepper crops. In addition, study into the potential of melatonin for stress relief in various horticultural and agronomic crops would aid in agricultural production development.