土壤水分及环境因子对刺楸叶片气体交换的影响

Effects of Soil Moisture and Microclimate Factors on Gas Exchange Parameters of Kalopanax Septemlobus Koidz

通过测定不同土壤水分条件下,3a生盆栽刺楸苗木的气体交换参数及其周围环境因子,探讨土壤水分及微气候因子对光合速率、蒸腾速率、气孔导度等气体交换参数的影响规律。结果表明:随着水分胁迫的加剧,刺楸叶片蒸腾速率、净光合速率和气孔导度总体上表现出减小的趋势,且随着胁迫的加剧,下降的幅度越大,蒸腾速率、净光合速率和气孔导度在重度、中度、轻度胁迫下日均值分别比对照下降6 6 % ,2 5 %和16 % ,81% ,30 %及5 1% ,70 % ,17%和14 %。随着土壤水分的减少,净光合速率下降逐渐由气孔限制转变为非气孔限制,水分利用效率并未完全表现出下降的趋势,日平均值表现为对照>中度>轻度>重度。逐步回归分析表明,刺楸苗木叶片水气交换参数,不仅受土壤水分的影响,同时也受外界环境因子的综合影响,且影响程度差异较大。

Gas exchange parameters in leaves of three-year-old Kalopanax septemlobus Koidz were studied under different soil water conditions and microclimate factors, in order to explore the effects of soil water stress and microclimate factors on the gas exchange parameters. The study resulted: with the decreasing of water supply, the Stomatal conductance、Net photosynthetic rate、Transpiration rate of Kalopanax septemlobus Koidz's leaf decreased, and with increasing of water stress, the degree of decreasing was significant. Compared with ck treatment, the mean of Transpiration rate、Net photosynthetic rate and Stomatal conductance in the water stress of severe treatment、moderate treatment、mild treatment had been reduced 66%,25% and 16%, 81%, 30% and 51%,70%, 17% and 14%. With the increasing of water stress, the predominant cause of restricting Photosynthetic rate had turn into non-stomata limitation, and Water use efficiency didn't fully decreased, the order of mean was ck>moderate treatment>mild treatment>severe water stress. The result of stepping multi-regression analysis suggested, not only soil water but also microclimate factors affecting the gas exchange parameters, the coefficient being preferable and the affecting degree being significant.