<正>采用田间试验的方法，研究了太湖地区两种水稻土（爽水型水稻土和囊水型水稻土）稻季磷素向下渗漏流失情况及其与土壤Olsen-P浓度的关系。结果表明：在每季度30kg/hm2常规施磷处理水平下，两种水稻土土壤渗漏水的溶解怒磷（Diss0IvedP，简称DP）平均浓度均远超过了水体富营养化的闻值（0.02mg/L）。施磷处理能显著增加30cm深度滂漏水磷浓度。土壤磷素渗漏迁移流失的主要形态是颗粒态磷（ParticulateP，简称PP）。爽水型水稻土和囊水型水稻土各处理土壤渗漏水PP/TP的平均值分别为70.9%和67.0%。囊水型水稻土稻季的磷素渗漏流失量约为每季度469.7g/hm2大于安镇爽水型水稻土378.5g/hm。爽水型水稻土和囊水型水稻土土壤渗漏水中磷浓度各存在一个突变点（Change-point），两者分别为33.0mg/kg和26.3mg/kg，即当爽水型水稻土和囊水型水稻土土壤（0～10cm）中的Olsen-P浓度分别大干33.0mg/kg和26.3mg/kg时，土壤30cIn深度的渗漏水磷浓度将随着O1senP浓度的增加迅速增大。两种水稻土突变点的差异可能与它们的有机质和黏粒含量不同有关。

Through the tests of potted plants and measurement photosynthesis, this paper studies responses of photosynthetic character of slash pine~s half-sib under water stress. There are 7 families compared with general slash pine (ab. CK). The net photosynthesis, stomatal conductance, CO2 concentration inside the cell, transpiration, water utilization efficiency, carboxylation efficiency and photosynthetic quantum yield are measured under different water strees (slight water stress while soil water content is 55% to 60%, moderate water stress while soil water content is 35% to 40% and heavy water stress while soil water content is 20% to 25%). The law of photosynthetic character with water stress is that Pn, Cond, Ci, Tr, WUE, φ and CE of slash pine’s half sib drop with increased of water stress. The Pn, Ci, CE also drop line. It also shown that the wup go to up firstly, then drops after moderate water stress. TheCond and Tr tend to 0 with heavy water stress. The photosynthetic character value of slash pine’s halfsib is better than that of general slash pine. It is one of the physiological causes with fast growth and high yield of slash pine’s half-sib.