Study on seedling growth of white poplar hybrid clones under the conditions of water stress

With double cross hybrid clones of white poplar as the experimental materials, the seedling growth of the clones was studied under the conditions of water stress. The result showed that water stress had impact on leaf growth, seedling height and biomass. Leaf growth of the seedling was restrained by water stress lightly. With the development of water stress, the period of leaf rapid growth moved up and the duration of the period of rapid growth protracted. But the rate of growth of leaf stressed was lower and there was not obvious peak, the single leaf area reduced obviously with development of water stress.The effect of water stress on leaf area was greater than on height growth.The height growth of seedling was obviously restrained when the soil water content droped to 60%.The fitting soil water content for the biomass accumulation of root, stem and leaf was 60% and with more drop of water content the accumulation of dry material of plant was restrained gradually. The influence of water stress on biomass of stem and leaf was more obvious than on the biomass of root. Therefore,with developing of water stress, the ratio of stem and root was reduced distinctly. Significant differences existed among clones on growth indexes and drop extent of the indexes with water stress. There were positive correlation among most indexes. That showed adaptability of the indexes to water stress was accordant.