关键词: 根系, 水力再分配, 水量大小, 根土界面, 养分循环

Abstract: Hydraulic redistribution (HR) in plant roots is a common phenomenon. The water magnitude of HR is related to measurement methods and influencing factors. The main methods for HR measurement include soil moisture dynamic method, isotope labeling method, sap flow method, and Ryel model method. Given that each method has its shortcomings, the result from single method should be treated carefully. Two conditions are needed for the occurrence of HR. First, soil water potential (ψ_s) is less than leaf water potential (ψ_l), with the cease of canopy transpiration. Second, there is obvious spatial heterogeneity of soil moisture in the rhizosphere. HR can relieve drought stress of plants and their neighboring plants, promote soil nutrient cycling, and then facilitate plant nutrient uptake (such as nitrogen and phosphorus). As a result, HR has great ecological significance in plant hydraulic safety, and ecosystem nutrient cycling and balance. Although there have been great progresses on plant HR, there are still deficiencies in the research methods and the accuracy evaluation of quantitative determination of HR. In addition, HR research on plants living in special habitats also needs to be strengthened. Future HR research should focus on the combination of multiple technologies, with the aim to comprehensively understand the generating mechanism and to quantify its magnitude.

Key words: root, hydraulic redistribution, water volume, root-soil interface, nutrient cycling.