石漠化地区3个树种幼苗在水分胁迫下的光合特性与抗旱性关系

采用盆栽控水方法,研究了翅莢木、滇楸和银荆树3树种当年生实生苗的光合特性与抗旱性的关系.结果表明:随着干旱胁迫强度的增加和时间的延长,3树种的净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均呈下降趋势,而胞间CO2浓度则呈上升的趋势;净光合速率日变化曲线逐渐从典型的单峰型转变成双峰型,出现"光合午休"现象.在轻度胁迫和中度胁迫下,净光合速率的降低是由气孔因素和非气孔因素共同引起的:而重度胁迫下,净光合速率的降低主要是非气孔因素引起的.干旱复水后,3个树种的净光合速率均有明显的恢复.利用隶属函数与反隶属函数法对3个树种的抗旱能力进行综合评价,其抗旱能力为:银荆树＞翅莢木＞滇楸.

Relations between Seedlings' Photosynthetic Characteristics and Their Drought Tolerance under Water Stress in Rocky Desertification Area

Water-controlling pot experiments were carried out on characteristics of photosynthesis and drought tolerance under water stress of 3 tree species:Zenia insignis,Catalpa fargesii f.duclouxii and Acacia dealbata from a rocky desertification area in Guizhou Province.The results were as follows:As stress increasing and time delaying,the net photosynthesis rate(Pn),transpiration,stomata conduct were gradually decreased but CO_2 concentration in stomata was increased;the diurnal pattern of net photosynthetic rate shifted gradually from a typical single-peaked curve to a double-peaked one that signified midday depression of photosynthesis.The midday depression of photosynthesis under both light and heavier stress may be induced by a combination of stomatal limitation and non-stomatal factors,but under extreme drought conditions,induced mainly by the non-stomatal factors.The depressed Pn could recover when rehydrated under certain drought stress.By a comprehensive evaluation of Fuzzy mathematics,the ability of drought tolerance was arranged from strong to weak as following:Acacia dealbata>Zenia insignis>Catalpa fargesii f.duclouxii.