Study on Change Regulation of Physiological and Biochemical Substances in Leaves and Branches Before Defoliation of Ginkgo biloba L.

Taking male and female ginkgo before defoliation as materials,the changes of photosynthetic pigment and protective enzymes activity as well as the change regulation of organic and inorganic nutrients were studied,in order to investigate the changing rule of the physiological and biochemical substances in ginkgo leaves on the eve of nutrient transfer and blade.The results showed that during the autumn,before leaves falling down,the chlorophyll content and POD activity reduced gradually in both female and male plants,whereas carotenoid content and SOD activity increased slightly first and then decreased gradually before defoliation.Starch,soluble sugar and soluble protein contents in leaves also reduced significantly,whereas these contents in branches increased significantly.Total nitrogen,phosphorus contents in leaves decreased slightly and the contents in branches rose correspondingly,whereas potassium content in leaves and branches had no significant change.Therefore,before leaves falling down,photosynthetic pigment contents and protective enzyme activities of ginkgo leaves reduced gradually with the senescence process of leaves;organic nutrition,nitrogen content and phosphorus content will transfer from leaves to branches.This ensured to reduce nutrient waste by fallen leaves and reserved more energy for the plant in winter.