Hydraulic lift（HL）, the exudation of water from root system of deeper rooted plants under soil desiccated conditions is considered as a potential irrigation system in drought areas. The ability of HL in sorghum（Sorghum bicolor（L．）Moench）was evaluated by a split root experiment with mixed-cropped rice（Oryza sativa L．）as an indicator plant for phytoassay. Growth parameters of rice and soil water conditions are measured after withholding irrigation with or without sorghum root connection between rice roots. Soil water content, soil water potential and stomatal conductance of rice leaves are ameliorated with the root connection, so that the transpiration rate of rice with root connection are１．６７ times higher than that without the connection. It is therefore suggested that measurments of transpiration and stomatal conductance of rice which is mix-planted with neighboring deep rooted plants are effective in quantification of HL.