effects of external copper on enzyme activity in soil and apple tree system

Effect of external copper on enzyme activity in a soil and apple tree system was studied by using cinnamon soil and ^Fuji^ apple young tree. The results showed that perioxidase, PPO and ascorbic acid oxidase activity in the leaves and perioxidase activity in the roots were reinforced at low external copper levels and reduced at high. Adding Ca of Fe at high copper levels could mitigate copper toxicity in some degree. A significant curuilinear correlation was observed between soil perioxidase activity and the external copper concentration (y = x/(-11.26 + 0.75x), r = 2.95/(1 + 0.57exp(-5.02 * 10~(-5)x)), r = -0.9820~(**)). Urease was very sensitive to copper and it lost activity at levels > Cu100.