科尔沁沙地黄柳气孔导度和水分状况随季节和地形的变化特征①

黄柳叶片气孔导度在上午８时后即呈下降趋势，下表皮气孔导度大于上表皮。干旱季节上下表皮气孔日间开启程度不同，下表皮气孔受环境因子的影响较大；湿润季节则相同。不同季节气孔导度值不同，下表皮气孔对季节变化反应灵敏。不同季节黄柳体内水分状况参数值不同，在５、６月份抗旱性最强；沙丘不同部位各参数值亦不相同，在沙丘中部和丘脚抗旱性最强，而在丘顶水分状况最好。湿润的７月黄柳一日内各时刻的膨压值均大于０，说明经期

Seasonal and Topographical Changes in Stomatal Conductance and Water State of Salix Gordejevii in Horqin Sandyland

Daily changes of stomatal conduction of Salix gordejevii decreased after 8 a.m. The value of stomatal conductance was higher on lower epidermis than upper one, and the stomata of low epidermis were more sensitive to the environmental condition. The value of stomatal conduction and the cell water parameter of Salix gordejevii was different during growth season. The drought resistance ability of Salix gordejevii varied at different part of sand dunes and different seasons. The shrub possessed highest drought resistance in May and June. Cell turgor pressure was always positive in humid July, which implied that although the cell turgor pressure of Salix gordejevii changed with environmental condition and stomatal regulation, the growth of plants was not affected.