土壤水分、光照和空气湿度对木薯气孔导度的影响

Effects of soil moisture,light,and air humidity on stomatal conductance of cassava(Manihot esculenta Crantz)

为探讨土壤水分、光照等环境因子对华南8号木薯气孔导度的影响,构建气孔导度与相关环境因子的数学模型,设置7个土壤水分梯度(相对含水量20%～80%),盆栽华南8号木薯,测量净光合速率、气孔导度和空气相对湿度等参数。结果表明:空气相对湿度与气孔导度之间呈极显著正相关;光合有效辐射、土壤相对含水量与气孔导度之间呈显著正相关,但它们对气孔导度的影响程度随土壤相对含水量的变化而变化,当土壤相对含水量较低时,土壤相对含水量是影响气孔导度的主导因子,而当土壤相对含水量较高时,光合有效辐射是影响气孔导度的主导因子;土壤相对含水量、光合有效辐射、空气相对湿度与气孔导度的关系可用指数模型表达;华南8号木薯的适宜土壤相对含水量的低限临界值为52%。

To assess the combined effects of soil moisture,light,and other environmental factors on the stomatal conductance of cassava（Manihot esculenta Crantz）,and to construct the mathematical models of stomatal conductance and related environmental factors,a gradient of soil moisture content at an interval of 10% within the range of 20%-80% was installed for the cassava cultivar SC-8 in a pot culture experiment,with the net photosynthetic rate,stomatal conductance,air humidity,and several other parameters measured.There was a significant positive correlation between air humidity and stomatal conductance.Photosynthetically active radiation and soil moisture content had significant positive correlations with stomatal conductance,but their affecting magnitude varied with soil moisture content.When the soil moisture content was low,it was the dominant factor affecting stomatal conductance;when the soil moisture content was high,photosynthetically active radiation became the dominant affecting factor.The relationships of stomatal conductance with soil moisture content,photosynthetically active radiation,and air humidity could be expressed with exponential model.Using the constructed model,we found that the lowest threshold of appropriate soil moisture content for cassava cultivar SC-8 was 52%.