Dynamics Of Biochemical Indexes For Youngling Of Four Tree Species Under The Periodical Change Water Supply Conditions

Water stress to plant not only restrict the yield of plant and restoration of vegetation,but also endanger the ecological safty and the sustainable development of society,economic. So,the studies on the relation ship between moisture and plant is one of the most important problem in the world.This thesis selected youngling of four tree species on the loess plateau:Robinia pseudoacacia , Acer truncatum , Pinus tabulaeformis and Platycladus orientalis as experimental material, connecting the developmental heterogeneity and thevariation of stress,connecting the style and levelof stress with the biochemical response of plant,considering the physiological water requirement heterogeneity of plant ,adopted rotable design and techique for enverimental control,studied the physiological and biochemical response to variable water stress in different growth stages during the plant annual growth period. The indexes included SOD activity,POD activity,content of MDA,Pro and ABA,Permeability of cell.The main results are as follows:1. During annual growth period,the supply of water in the early growth stage had the largest influence to the biochemical indexes in the leaves of the Robinia pseudoacacia seedling.The content of MDA,ABA and Permeability of cell increased with the increasing of the amount of supply water in the early growth stage. The suitable reducing to the supply water in the early growth is is favorable for Robinia pseudoacacia .2. During annual growth period,the supply of water in the early growth stage had the largest influence to the biochemical indexes in the leaves of the Acer truncatum seedling.The content of MDA,ABA and Permeability of cell decreased with the increasing of the amount of supply water in the early growth stage,the SOD activity inceresed with the increasing of water supply in the stage. The suitable reducing to the supply water in the early growth is favorable for Acer truncatum .3. The supply of water in the fast growth stage had the largest influence to the biochemical indexes in the leaves of the Pinus tabulaeformis seedling. The content of ABA and Permeability of cell increased with the increasing of the amount of supply water in the fast growth stage. So,the more soil moisture in the fast growth is bad for Pinus...