【摘要】 应用225MK3红外气体分析仪和压力室测定了侧柏、沙棘、新疆杨3树种离体小枝在不同脱水状况下的净光合速率、蒸腾速率、水势和饱和亏缺,分析了它们在年生长发育过程中光合生理生态特性变化及其对水分胁迫的反应,结果表明:(1)随着水分亏缺程度的加剧,其净光合速率呈下降趋势,可用方程y=a+b(1-EXP(-kx))来表述(2)净光合速率为零时的饱和亏缺有随其年生长发育时期变化的年进程变化。(3)3树种相对蒸腾速率与其饱和亏缺的关系曲线呈倒“S”型曲线,可用方程Y=K/(1+a*(-b*X))来表述(4)相对蒸腾速率最大变化率也有随其年生长发育期而变化的特征。在嫩枝生长初期其变化率较大,生长末期较小。更多还原

【Abstract】 The net photosynthetic rate,transpiration rate and water potential and saturated deficit of the sprig of the Platycladus orientalis,Hippophae rhamnoides,Populus albal.var.pyramidalis in different dehydrated condition were measured by using the 225mk3 type infrared carbon dioxide gas analyzer and pressure chamber instrument.The variation of the feature of photosynthetic eco-physiological characteristics and the responses to water stress in one year’s growth period was analyzed.The result indicated:(1)Transpiration rate decreased with the increased saturated deficit,and the relation showed y=a+b(1-EXP(-kx));(2)When the net photosynthetic rate was equal to zero,the saturated deficit of the sprig of the three kind of trees had annual and disciplinary variation in their growth period;(3)The relative curve between the relative transpiration rate and saturated deficit of the three trees were expressed as shape and the equation is Y=(1+a*(-b*X));(4)The maximal variation rate of the relative transpiration changed with the variation of one year’s growth period.When the twigs were in the early growth period the variation rate was larger,while the value in the terminal growth period was smaller.更多还原