不同土壤水分胁迫下沙漠葳的水分生理生态特征

Water Physio-ecological Characteristics of Chilopsis linearis under Different Soil Water Conditions

将美国西部引进的沙生灌木沙漠葳的2a生实生苗盆栽于土壤含水量分别为田间持水量的80％～90%（适宜水分）、50％～60％（轻度土壤水分胁迫）和20%～30％（重度土壤水分胁迫）条件下15～90d，研究其对土壤水分胁迫的水分生理响应。结果表明：土壤水分胁迫下，沙漠葳叶片的水势（ψs）、自由水含量（％）和相对含水量（RWC）降低，束缚水（协）、水分饱和亏（WSD）和Vs／％比值增大，叶片保水力减弱，蒸腾速率（Tr）加快，而组织总含水量基本保持稳定。各指标对土壤水分胁迫响应的敏感性有所不同。与适宜土壤水分相比，轻度土壤水分胁迫并未使RWC、WSD和保水力发生显著变化，而重度土壤水分胁迫才使三者发生显著变化，轻度和重度土壤水分胁迫均使ψs、Vs、Va、Vs／Va和Tr发生显著变化。随胁迫期的延长和胁迫的加重，沙漠葳的蒸腾速率可能成为一个纯物理过程而主要受控于外界环境因子的变化。

Chilopsis linearis, a kind of desert shrub was introduced from west of USA. The water physioecological responses of 2-year-old potted seedlings of C. linearis to different soil moistures were studied of 80%-90%（normal soil water）, 50% -60% （light degree soil water stress）, and 20% -30% （heavy degree soil water stress） . The results showed that soil water stress made water potential （ψs）, free water content （Va） and relative water content of C. linearis leaf decreased, bound water content （Vs）, water saturation deficiency （WSD） and ratio of bound water content to free water content （Vs/Va） increase, leaf water-holding ability weaken, transpiration rate （Tr） enhanced. Tissue total water content howerer, kept steady on the whole under different soil water stress. The response sensitivities of these indices to soil water stress were different. Middle degree soil water stress didn＇t make RWC, WSD and water-holding ability change obviously in comparing with that of light degree soil water supply, but high degree soil water stress made them changed clearly. Both middle degree soil water stress and high degree soil water stress made ψs, Vs, Va, Vs/Va and Tr changed obviously. The transpiration rate could be controlled mainly by leaf stomas under normal soil water supply, but controlled chiefly by circumstance factors under long and high degree soil water stress.