Water Use Efficiency And Response To Light Of Several Shrubs Indifferent Water Moisture In Sand Land Of Kubuqi

In ording to solve the contradiction between demand for the extension of forest vegetation andthe limited water supply in arid and semi-arid area and based on the theory of soil-plant-atmosphere continuum, the dissertation chose the main afforestation tree species including Tamarix ramosissma Ledeb Caragana microphylla and Hedysarum mongolicum Turcz .to forest project in Growing Seasons in 2006,utilized advanced apparatus, equipments and various approaches, systematically analyzed of relationship between soil water content and light intensity and growing and photosynthesis characteristics. These studies could provides the scientific bases for accurately estimating ecological water consumption and the choice of tree species and the properly arrangement of stand density. The dissertation involved following aspects:1: Study on reposing to light of Tamarix ramosissima Ledeb, Caragana microphylla and Hedysarum mongolicum Turcz in different soil moisture;2: Study on suitable water content of Tamarix ramosissima Ledeb, Caragana microphylla and Hedysarum mongolicum Turcz;3: Study on diurnal course of Tamarix ramosissima Ledeb, Caragana microphylla and Hedysarum mongolicum Turcz in different soil water content; By studying the result show that:The relation of diurnal course of photosynthetic rate(Pn) , transpiration rate(Tr) and water use efficiency of leaf (WUE) and soil water content is close, and response to SWC is obvious, withered moisture of three shrubs is separately 1.09%,0.71%,0.68%.Study on the relation among photosynthesis rate, stomatal conductance, transpiration rate, water use efficiency and soil water content. The result show the suitable water content of Tamarix ramosissima Ledeb is 10.1% ～ 13.6%, Caragana microphylla is 11.0% ～ 13.4%,and Hedysarum mongolicum Turcz is9.9%～15.0%.Photosynthetic rate, transpiration rate and water use efficiency of leaf have clear threshold value response to photosynthetic active radiation. the fitting sphotosynthetic active radiation cause higher sunshine use efficiency and water use efficiency of Tamarix ramosissima Ledeb is 980～1500μmol·m^-2·s^-1, the fitting sphotosynthetic active radiation cause higher sunshine use efficiency and water use efficiency of Caragana microphylla is 800～1800μmol·m^-2·s^-1, the fitting sphotosynthetic active radiation cause higher sunshine use efficiency and water use efficiency of Hedysarum mongolicum Turcz is 800～1500μmol·m^-2·s^-1.