沙冬青对土壤水分变化的生理响应

沙冬青(Ammopiptanthus mongolicus(Maxim))是生长在沙漠地区及干旱荒漠区的常绿灌木,在干旱环境条件下形成了独特的生物学特性与生理生态适应性。研究结果表明,灌水前后沙冬青的光合作用和蒸腾作用变化很大。在土壤干旱时,其光合速率变化的日平均值仅为2.14μmol·m^-2·s^-1,其最大值仅为3.5μmol·m^-2·s^-1;此时叶片蒸腾速率变化的日平均值为7.03mmol·m^-2·s^-1,最大值为10.5mmol·m^-2·s^-1。而在土壤水分充足时,其光合强度和蒸腾强度明显提高,叶片光合速率的日平均值为5.97μmol·m^-2·s^-1,最大值为8.5μmol·m^-2·s^-1,均为干旱时的2倍以上;此时叶片蒸腾速率的日平均值为23.5mmol·m^-2·s^-1,最高值达30.1mmol·m^-2·s^-1,均为干旱时的3倍左右。分析沙冬青叶片气孔的调节作用与叶片的光合作用和蒸腾作用的关系可知,其气孔活动与蒸腾作用保持较为密切的相关关系,而其光合作用虽然也受气孔活动的影响,更主要是与其自身的生理生化特性有关。

Physiological Responses of Ammopiptanthus mongolicus (Maxim) to Change of SoilMoisture

Ammopiptanthus mongolicus (Maxim) is the only one of evergreen shrubs in desert region. Its biological feature and adaptation are important for studying the mechanism and diversity of desert plants. The result showed that under soil drought condition, the average and maximum of photosynthetical rate in leave of A. mongolicus is separately 2.14 μmol·m^-2·s^-1 and 3.5 μmol·m^-2·s^-1;And those of transpiration rate 7.03 mmol·m^-2·s^-1 and 10.5 mmol·m^-2·s^-1. However, when the soil is moist, the average and maximum of photosynthetical rate and transpiration ra te in leave of A. mongolicus are separately two and three times as those under drought condition. Through analysis of stomatal activity in leave, it was kno wn that the stomatal activity is closely related to leaf transpiration. The photosynthesis in leave is regulated by not only the stomatal activity but the bioch emical processes. This needs a further study in the future.