干旱胁迫对大豆气孔特征和光合参数的影响

利用盆栽法对大豆进行了不同梯度的水分处理，以研究不同水分胁迫条件对大豆气孔特征和光合特征的影响。试验结果表明：随着水分胁迫强度的增加，大豆叶片的气孔长度、宽度、周长、面积均呈减小趋势，气孔密度呈增加趋势。轻度水分胁迫条件下，大豆叶片的净光合速率（Pn）日均值较高，而在充分灌水条件下，大豆叶片的最大光量子效率值（Fv/Fm）较高，不同水分胁迫处理之间叶绿素含量没有显著差异。不同水分胁迫下大豆的净光合速率与气孔导度间均存在极显著相关关系，而气孔导度与单一气孔特征之间无显著相关关系，表明气孔传导力是大豆光合能力的主要限制因素之一，但同时也存在非气孔限制因素。实验中大豆生长的最适宜土壤相对含水量是60%～65%，此时的光合速率下降是由气孔限制引起。当土壤相对含水量低于60%时，光合作用的非气孔限制因素开始出现。当土壤相对含水量在35%～40%时，非气孔限制逐渐成为大豆叶片光合能力下降主导因子，并可能导致光合器官受到损伤。

Effects of Drought Stress on Soybean Stomatal Characteristics and Photosynthetic Parameter

The effects of different degrees water stress on soybean stomatal and photosynthetic characteristics were investigated based on watering experimentation in self made pot. The results showed that with the increasing of water stress intensity, soybean stomatal length, width, perimeter, and area all decreased, while the stomatal density showed an increasing trend. Under slight water stress, the average daily value of soybean leaf blade Pn was higher, while under sufficient irrigation, its Fv/Fm value was higher. There were no significant differences between chlorophyll contents by different water stress treatment. Under different water stress, no significant correlationship was found between the net photosynthetic rate and stomatal conductivity. While there was no significant correlationship between stomatal conductivity and single stomatal characteristics, indicating that the stomatal conductivity was one of the factors limiting soybean photosynthetic ability. In this experiment, the optimum soil relative moisture content was 60%~65%. The falling of photosynthesis rate is brought by stomatal limitation. When soil relative moisture content is below 60%, the non stomatal limitation emerged. When the relative soil moisture content was 35%~40%, the non stomatal limitation gradually became a dominant factor in declining soybean leaf blade photosynthesis ability, which could lead to harm of photosynthesis organ.