Study On The Water Physio Characteristics And The Adaptation Towater Stress For Sweden Short Rotationcoppice Willow

Using nine variety( from Sweden and Shanxi)of Salix as materials, this paper mainly deals with the drought-resistant characters and mechanism of nine variety of Salix from the aspects of water physiological ecology, photosynthesis, and protection enzyme system anti-oxidation under field experiment and potted experiment. On the basis of the study on the growth and physiological characteristics, index system on comprehensive judgment of drought-resistance ability of the variety was suggested and the drought resistance ability of the variety were judged comprehensively. The main results were as follow:1. The differences of drought-resistance to water stress of nine variety of Salix mainly due to the result of their long-term adaptation to the environment of their original inhabit. There were stable genetic features in morphological character, physiology and ecology, so it is significantly important to evaluate later-generation.2. The drought-resistance mechanisms of four variety were deferent. Under drought stress, variety C has the high specific leaf dry weight, strong ability of leaf water holding, low transpiration ; thick and hard cell wall, high water-maintenance, strong ability of anti-oxidation; under sever drought stress, it has the characters of low productivity and high water use efficiency;variety C's water potential, cellular elasticity, drought-resistance productivity and water use efficiency dropped dramatically, And it closed its stomas early to minimize the loss of water; its ability of cleanup of protection enzyme system lost the balance too soon, leading to the rapidly accumulation of the H₂O₂,and high electrolyte leakage. Variety 2 has the characters of low transpiration, high root/shoot biomass ratio, high turgor maintaining and osmotic adjustment; its ability of cleanup of protection enzyme system is solely inferior to variety C and it has stronger potential drought-resistance; under sever drought stress, it closed its stomas later to maintain photosynthesis rate, and still can accumulate dry materials to some degreed. Variety 2 has low water potential and water-maintains, normal ability of leaf water holding, its ability of adaptation to water stress and drought-resistance productivity was inferior to variety 2 but stronger than those of variety C. 3. Water parameters(Ψ_Ï€sat,Ψ(Ï€tlp),WSD_tlp,ε)and drought-tolerance of four variety have a seasonal change, the reasons of this changes can be found from physiology and structure during the course of the growth and development of trees. During the period of leaves expanding, these Water parameters reflect their ability of drought-tolerance is weaker, while it happen to lower soil water content, so this period can be called the"ecological weak time".4. The indices adaptability to drought and of productivity to drought were analyzed. The leaf water-losing rate,photosynthesis, transpiration,water use efficiency and protection enzyme system anti-oxidation and the ability of osmotic adjustment were suggested to be used as comprehensive judgment indexes in drought-resistance variety selection. Variety 2 and variety 2 have a better ability of water adaptability and drought-resistance productivity, Variety C has a faster speed of growth under the normal water condition, but its ability to adapt water stress is weaker, Variety C has the strongest ability of drought-resistance, but it has a normal speed of growth. The principle of suitable trees for suitable areas should be considered in the plantation of Salix.