逐渐干旱对绵毛水苏光合特性的影响

以绵毛水苏为试材,研究其在4种土壤相对含水量（100%、75%、50%、25%）条件下,即在逐渐干旱条件下土壤含水量、光合速率、气孔导度、胞间CO₂浓度及蒸腾速率等的变化规律。结果表明:随着水分胁迫的加剧,叶片的净光合速率（Pn）和气孔导度（Gs）下降,胞间CO₂浓度（Ci）呈现在轻度和重度胁迫的条件下升高,在中度胁迫的条件下下降的现象。表明适度的轻度水分胁迫不会显著降低绵毛水苏的净光合作用和气体交换。75%～50%的土壤相对含水量最适合绵毛水苏的生长;同时发现与干旱胁迫相比,水分过多也不利于绵毛水苏的生长。

Effects of Gradual Drought on Photosynthesis Characteristics of the Stachys lanata

Physical characteristics represented by the Stachys lanata,including net photosynthetic rate（Pn）,stomatal conductance（Gs）,intercellular CO₂ concentration（Ci） and transpiration rate（TRN） were experimentally studied under the condition of 100%,75%,50%and 25%relative soil moisture contents.The results showed that Pn and Gs declined with the increase of water stress.Ci increased under the lower and higher water stress conditions,while it declined with the medium soil water stress.It states Pn and Gs of Stachys lanata does not significantly decline under light water stress condition The most suitable relative-soil moisture content for the Stachys lanata was in the range of 50%～75%. Comparing with the drought stress,too much moisture would negatively affect the to the growth of the Stachys lanata.