Critical value of copper for hydrolytic enzymes in soil and plant growth and development in sugarcane.

A pot culture experiment was conducted using sugarcane variety GT21 and different Cu concentrations. The results showed that the invertase and urease activities increased initially up to certain level and then decreased with increase of total Cu concentration in soil. The maximum activities of enzymes have been recorded in the range of 86.65 mg/kg to 94.15 mg/kg Cu in soil. The plant height, stalk diameter, cane yield, and juice brix increased and attained maximum values at 269.15 mg/kg. At the 269.15 mg/kg concentration of Cu in soils, the total Cu content in cane was observed as 7.82 mg/kg. Our studies revealed that the critical values of Cu in soil ranged between 86.65 mg/kg -94.15 mg/kg, above which the soil enzyme activities decreased significantly. While for sugarcane growth, critical values of Cu in soil was found to be 269.15 mg/kg. Further, soil invertase and urease enzymes may be used as biochemical markers for heavy metal (Cu) pollution in soils.