DISTURBANCES IN GROWTH, YIELD, SUCROSE CONCENTRATION AND ANTIOXIDATIVE DEFENSE SYSTEM BY EXCESS COBALT IN SUGARCANE

The aim of the study was to implicate induction of oxidative stress and antioxidative responses with the effects of cobalt excess on sugarcane plants. Sugarcane (Saccharum officinarium L.) cv. 'CoS 99225' grown in refined sand at excess cobalt i.e. 100, 200, 300, 400, and 500 mu M. The effect of excess cobalt (300 mu M) was observed on sugarcane as interveinal chlorosis and necrotic spots in middle leaves. Later, affected leaves turned necrotic, dry, and withered. The toxicity of cobalt was also discernible on root weight, cane yield, reduced concentration of sucrose in cane juice, carotenoides, Hill reaction activity, chlorophylls, iron (Fe), relative water content, decreased activity of catalase in leaves, and increase in concentration of lipid peroxidation, phenols, sugars, starch, proline and higher activity of peroxidase, ascorbate peroxidase and superoxide didmutase and accumulation of cobalt in sugarcane leaves.