Effects of different application rates of humic acid compound fertilizer on leave nutrient accumulation and physiological mechanism of grape

The effects of different application rates of humic acid compound fertilizer(HA) on nutrient accumulation and physiological characteristics of two-year old grape(Kyoho)were studied.The results show that different application rates of HA can affect the physiological activities and nutrient accumulation of grape. Superoxide dismutase(SOD)activity is improved significantly when the application rate of fertilizer is lower than 1.75g/plant,and decreases gradually when the application rate is higher than 1.75g/plant.The peroxidase(POD)activity reaches the highest point when the application rate of fertilizer is 3.50g/plant,then with the increasing of application rate,POD activity in HA treatment is decreased significantly.That of inorganic compound fertilizer treatment changes smoothly.The change of transpiration rate is consistent with that of POD activity.Compared to inorganic fertilizer,HA compound fertilizer can promote N,P,K to be absorbed and utilized by grape.