Changes in growth, biochemical constituents, and antioxidant potentials in radish (Raphanus sativus L.) under cobalt stress

The effects of cobalt (Co) stress on seedling vigor, photosynthetic pigment content, biochemical constituents, mineral status, and the activity of antioxidant enzymes in Raphanus sativus L. were studied. The plants were raised in earthen pots containing soils amended with different concentrations of Co (50, 100, 150, 200, and 250 mg kg^-1). Growth parameters (root and shoot length, and total leaf area), photosynthetic pigments content (chlorophyll a, chlorophyll b, and total chlorophyll), biochemical constituents (total sugar, amino acid, and protein content), mineral content (macro- and micronutrients), and the activity of antioxidant enzymes (catalase (CAT), peroxidase (POX), and polyphenol oxidase (PPO)) were analyzed 30 days after sowing (DAS). All measures increased at the 50 mg Co kg^-1 soil level when compared to the control. Further increases in the Co level (100-250 mg kg^-1 soil) had a negative effect on these parameters.