Effect of Rhododendron arboreum Leaf Extract on the Antioxidant Defense System against Chromium (VI) Stress in Vigna radiata Plants

In the current investigation, we studied role of Rhododendron leaf extract in Vigna radiata grown under chromium metal stress. We observed that seed treatment with Rhododendron leaf extract resulted in the recuperation of seedling growth under chromium toxicity. Seed treatment with Rhododendron leaf extract significantly improved the contents of anthocyanin and xanthophyll pigments under stress. The antioxidative defense system triggered after Rhododendron extract treatment, resulting in the increased actions of antioxidant enzymes. Oxidative stress induced by the assembly of reactive oxygen species was reduced after Rhododendron extract treatment under chromium toxicity as indicated by the enhanced contents of non-enzymatic antioxidants, namely ascorbic acid, tocopherol, and glutathione. Furthermore, Rhododendron leaf extract treatment under chromium metal stress also encouraged the biosynthesis of organic acids, polyphenols, as well as amino acids in Vigna radiata. Statistical analysis of the data with multiple linear regression also supported that Rhododendron leaf extract can effectively ease chromium metal-induced phytotoxicity in Vigna radiata.