毛乌素沙地中间锦鸡儿幼苗生长、气体交换和叶绿素荧光对模拟降水量变化的响应

选择毛乌素沙地优势灌木中间锦鸡儿为研究对象，人为控制4种降水量水平来测定中间锦鸡儿幼苗的形态，。生物量干重，气体交换和叶绿素荧光参数，结果表明，不同施水量显著影响幼苗株高，基径，叶数，叶面积，生物量干重，净光合速率，蒸腾速率，气孔导度以及水分利用效率，157．5mm和630mm施水的幼苗以上参数显著低于472．5mm施水的幼苗，157．5mm和630mm施水量的幼苗PSIII光化学效率和最大荧光与初始荧光比显著小于472．5mm施水量的幼苗；不同施水量对幼苗生物量干重分配有显著影响；随着施水量增加，根冠生物量干重比显著减少。

Effect of simulated precipitation change on growth, gas exchange and chlorophyll fluorescence of Caragana interme.dia in Maowasu sandland.

Morphology, biomass, gas exchange and chlorophyll fluorescence were measured for seedlings of C.intermedia ,a dominant shrub, to the change of global precip ita tion by artificially controlling the water supply at four levels. The results sh owed that the seedling variables, such as plant height, stem diameter, leaf numb er, leaf area and dry biomass, photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency, were affected by different water supply, and those variables of the seedlings treated by the 157.5mm or 630mm water supp ly were significantly less than those of the seedlings treated by the 472.5mm wa ter supply. PSII photochemical efficiency and maximal fluorescence/initial fluor escence of the seedlings treated by 157.5mm and 630mm water supply were much sig nificantly lower than those of the seedlings treated by 472.5mm water supply. Wa ter supply obviously affected dry biomass distribution of the seedlings, and the root / shoot dry biomass clearly decreased with the increase of water supply.