Chrysin mitigates copper stress by regulating antioxidant enzymes activity, plant nutrient and phytohormones content in pepper

Copper (Cu) has an important role in physiological processes. High concentrations of Cu can cause toxic effects for plants. To evaluate the effect of Cu and chrysin (Chr) on the seedling growth, some physiological and biochemical properties of pepper, a factorial experiment in a completely randomized design was carried out. The treatments were T1= Control, T2= 0.1 mM Chr, T3= 0.5 mM Chr, T4= 50 mM Cu, T5= 50 mM Cu+ 0.1 mM Chr and T6= 50 mM Cu+ 0.5 mM Chr. Plant morphological characters were significantly affected by Cu and Chr treatments. The results showed a significant decrease in plant growth parameters due to Cu stress while Chr alleviated negative impacts of Cu on growth these parameters. The hydrogen peroxide (H2O2), malondialdehyde (MDA), prolin and sucrose content increased in pepper seedlings grown under Cu stress conditions. The MDA and H2O2 content showed a decrease with the effect of Chr treatment. Chr treatments also increased prolin and sucrose content of pepper plants under non-stressed conditions. Catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) enzyme activity elevated considerably compared to the control plants under Chr treatments. Moreover, higher values were observed for Chr treated plants under Cu stress. The findings of the study showed that Cu stress lowered all plant nutrient elements except for Cu content. 0.1 and 0.5 mM Chr treatments increased plant nutrient elements content of pepper seedlings under normal and Cu stress conditions. In conclusion, Chr mitigates Cu stress by regulating antioxidant enzymes activity, plant nutrient and phytohormones content in pepper.