土-根界面行为对单根吸水的影响

The influences of soil root interface behavior on roots uptake soil water

本文主要讨论了冬小麦根尖在土壤水分胁迫下发生收缩，产生土根空气界面（ψｓ≤－０１ＭＰａ），从而影响土壤根系的水分动力学性质．试验观测到的最小根直径为初始根直径的５２％（ψｓ＝－１１ＭＰａ）．土根界面厚度随根直径的减小而增大，最大厚度为０１１７ｍｍ．土壤充分供水（０—－０１３ＭＰａ），根径向导度最小，是根吸水的限制因素；土壤水分胁迫（－０１２—－１０５ＭＰａ），土根界面导度最小，变为根吸水的限制因素；土壤严重干旱（＜－１０５ＭＰａ），土壤导度最小，土壤水分不足限制了根吸水．

Roots shrink under some environment condition, its degree increases with the decrease of soil water potential. Winter wheat root tips shrink to about 52% of their original diameter when their water potential decreases to -1 1MP. Water movement to or from a root depends on soil effective conductance Cs, soil root interface conductance Csr and root conductance Cr. Water movement into roots from wet soil during 0—0 13MP is limited by Cr. As soil becomes dry, water movement was limited mainly by Cr. As the soil continues to dry, water movement is dominated by Cs.