Responses of growth and antioxidative enzymes to different Ni concentrations in castor bean (Ricinus communis)

Abstract

A pot culture experiment was conducted to investigate the effect of different levels of nickel on growth and biochemical parameters of castor bean (Ricinus communis L.). Castor seedlings were grown in control conditions or in soil amended with 50, 100, 300 and 500 mg kg^‑1 of Ni. Plants were harvested after 60 days of sowing. A significant decrease in growth, and concentration of chlorophyll and carotenoids were observed with increasing concentrations of Ni. Leaf proline and malondialdehyde concentration increased considerably in response to Ni application. It was observed that the protein concentration in the leaves of castor plants decreased significantly with the increase in Ni concentrations in soil. An increase in protein content and enzyme activities was observed at increasing Ni concentration in soil. Significant changes in the antioxidative enzyme activities were observed in R. communis treated with varying Ni doses. It was found that with increasing concentrations of Ni in soil, the activity of the enzymes also increased. This suggests that the increase of enzyme activity due to Ni toxicity might play a role in the defence response of R. communis.