Cadmium phytotoxicity in cabbage

Cabbage (Brassica oleracea var. capitata) cv. Pride of India was grown in refined sand with complete nutrient solution for 36 days. On 37^th day pots with plants were divided in three lots. One lot of plant was maintained with complete nutrient solution and served as control. In other two lots cadmium at 0.1 and 0.5 mM was added as cadmium sulphate. Visible effects of excess Cd initiated after 7 days of metal supply. Growth of cabbage was depressed and the leaves of inner whorls (mature young leaves) developed diffused yellowing initiating from apical margins at 0.5 mM Cd supply, with increase in age chlorosis spread to inner side and gradually covered the upper half of the affected leaves. Old leaves hang downward and no proper head was formed, as most of the leaves were loosely arranged. The symptoms were most severe at 0.5 mM and less so at 0.1 mM Cd. In cabbage owing to excess cadmium fresh weight and dry weight decreased. The concentration of iron, phosphorus and sulphur (in tops), chlorophyll ‘a’ and ‘b’. Hill reaction activity, reducing sugars, activity of catalase and peroxidase and protein content were decreased considerably. Whereas, activity of acid phosphatase, ribonuclease, non-reducing sugars, starch and cadmium concentrations increased in tops and roots of cabbage.