Abstract: A hydroponic experiment was conducted to study the effects of different N forms on root growth and water Absorption of lowland and upland rice plants.Root dry weights of lowland and upland rice plants supplied with ammonium nutrition were lower than those with nitrate nutrition,while the amount of root bleading sap and water absorption per root surface area were higher in the plants supplied with ammonium nutrition than in those with nitrate nutrition.It was demonstrated that the aquaporin pathway of water absorption is the main approach of lowland and upland rice roots supplied with three different N forms,but the capacity of aquaporin for water transportation in lowland and upland rice roots was higher in ammonium nutrition than in nitrate nutrition.Moreover,upland rice was more adaptive to nitrate supply than lowland rice.

Key words: lowland rice, upland rice, nitrogen form, aquaporin, root bleeding sap, water absorption

摘要： 为研究不同形态氮素营养对水稻和旱稻根系生长及水分吸收的影响，采用水培供应不同形态氮素(铵态氮、硝态氮、铵态氮和硝态氮混合)的方法培养水稻和旱稻，并对水稻和旱稻的根系形态进行了扫描分析；同时，通过测定根系伤流液和采用HgCl2抑制水通道蛋白活性的方法，比较了水稻和旱稻根系对不同氮素形态响应的差异。 铵态氮营养水稻（或旱稻）的根干质量明显低于硝态氮营养水稻（或旱稻），但单位根表面积的水分吸收与根系伤流液量比硝态氮营养高；3种形态氮素营养水稻（或旱稻）运输水分的主要方式均是水通道蛋白的跨膜运输途径，但铵态氮营养水稻（或旱稻）的根系通过水通道蛋白跨膜运输途径运输水分的能力明显高于硝态氮营养水稻（或旱稻）；与水稻相比，旱稻对硝态氮营养具有较强的适应性。

关键词: 水稻, 旱稻, 氮素形态, 水通道蛋白, 根系伤流液, 水分吸收, 根系形态