Studies On Water Use Efficiency Differences Of Genotypes And Their Mechanism Of Physiology And Biochemistry In Populus Under Different Water Treatments

Along with the severe drought trend all over the world, more and more scientists have dedicated to the research on plant drought resistance and water saving. But only to improve the water use efficiency (WUE) of plant, to let them produce further yield from per drop of water, the new progress may be achieved. Populus is one of the most popular trees in artificial intensive forestry, to select fast growing clones with high WUE rapidly and efficiently is exigent desire of breeding researcher. In order to provide theoretic foundation and feasible techniques for forestry breeding, difference and the mechanism of the difference of WUE in Populus clones has been studied through stimulant natural drought and gradual drought of soil. Our results indicate that the differences in Populus clones are significant, J2, J6, J7, J8, J9 are excellent clones ,their biomass are more and WUE are high; δ 13C can be as a surrogate for high WUE genotype; For high WUE clones, the decline extent of leaf area and moisture content are smaller, the leaf moisture retaining power are stronger under stimulant natural soil drought; the accumulation of proline (Pro) and malondehyde (MDA) are lower, the activity of superoxide dismutase (SOD) and peroxide enzyme (POD) are weaker. To economize on water and high photosynthetic capacity are inseparable sides of WUE difference mechanism on yielding capability, low stomatal conductance induced by big stomata frequency and small size may be the reason for water saving. The distribution ratio of photosynthate between root and shoot is another factor that may be contribute to the WUE difference mechanism, for the high WUE clones usually have optimal ratio of root to shoot.