Hydraulic Conductivities in SoilRoot System and Relative Importance at Different Soil Water Potential and Temperature

In this paper, based on the experimental data of maize, sunflower, acacia confusa and leucaena glauca under various treatments of temperature and soil water potential , the effects of temperature and soil water potential on root shrinkage and the hydraulic conductivity in the gap of soilroot interface as well as the relative importance of hydraulic conductivities in soilroot system　were analysed.　The results indicated that root shrinkage has apparent difference for different four kind plants in experiment, i. e.， maize >sunflower>acacia confusa > leucaena glauca, the root shrinkage state under water stress reflect the droughtresistance of plant. At same soil water potential, the conductivity in the gap of soilroot interface is that leucaena glauca>acacia confusa > sunflower >maize. Among the gap conductivity (L_ｇ)，root system conductivity (L_r)　and soil effective conductivity (L_s), the change range of L_s is largest, and that of L_r is smallest. Wether one of L_r, L_ｇ and L_s　is the factor limited water transport in soilroot system or not, is determined by soil water potential range, when soil water potential (ψ) is larger than -1.0 MPa, tempeature increase or decrease has not apparent effect on root shrinkage for maize and sunflower, when ψ is lower than -1.0MPa, the root shrinkage is increased as temperature increases.