黄土区4个树种水势特征的研究

采用压力室法对晋西北黄土区柠条 (Caraganakorshinskii)、河北杨 (Populushopeien sis)、北京杨 (Populusbeijingensis)和小叶杨 (Populussimonii) 4个树种的小枝水势、叶含水率及其环境因子的日变化进行了定期测定。分析了 4个树种水势日变化与光照 (L)、气温 (T)、相对湿度 (RH)日变化及叶含水率 (LWC)日变化的关系以及其水势的季节变化与土壤水分季节变化的关系。主要结果如下 :整个生长期所测 4个树种小枝水势的日变化为呈抛物线型。生长期小枝水势的平均值分别为柠条 (- 1 .569MPa)、河北杨 (- 1 .0 30MPa)、北京杨 (- 0 .993MPa)和小叶杨 (- 0 .971MPa)。小枝水势与环境单因子的相关性大小依次为 :光照、气温、相对湿度。水势与光温复合因子 (L T)、光湿复合因子 (L/RH)的相关性大于它与单因子的相关性。小枝水势与叶含水率的相关性较差。生长期清晨水势 (Wp)季变化与土壤水分 (X)季节变化的最佳关系模型为Wp =Ae-BX型。但生长期午间水势的季节变化与土壤水分季节变化的关系均不显著。土壤水分含量对水势有较大影响。

A STUDY ON WATER POTENTIAL CHARACTERISTICS IN FOUR TREE SPECIES IN LOESS REGION

By the method of pressure chamber we monitored the diurnal change of water potential (Wp) of small branch in 4 tree species ( Caragana korshinskii, Populus hopeiensis, Populus beijingensis and Populus simonii ) once a month. The correlation between Wp and temperature (T), light intensity (L), relative humidity (RH) and leaf natural water content (LWC) were analyzed respectively; the correlation between Wp in the morning and soil water content was studied. The results were as follows: The diurnal change curve of water potential in four species is parabolic shape. The average value of potential in the species in growing season was respectively: Caragana korshinski (-1.569 MPa), Populus hopeiensis (-1.030 MPa), Populus beijingensis (-0.993 MPa )and Populus simonii (-0.971 MPa). The order of fitness degree between Wp and single climatic factor was L, T then RH. The correlation between Wp in the species and the products (L*T) of light intensity and temperature, the quotient (L/RH) of L and RH was more significant than with that of single climatic factor (T, L, or RH), respectively. The correlation between Wp and LWC is not very significant. The model type of Wp in predawn with soil water content(X)was: Wp = Ae -BX . Soil water moisture put more influence on predawn water potential 4 tree species.