The Experimental Research Of Water Move Through Soil-Spring Wheat System

The results of water move through soil-spring wheat system are:research on soil evaporation characteristics under different amount of perlite cover and the transpiration of potted spring wheat which was measured with sap flow method using heat balance technique under3water treatments(high、middle and low) in artificial climate chamber, where the light、 temperature、humidity and wind speed were240umol·m-2·s-1、25℃、45%�'�1.1m·s-1and the results were calibrated by weighing method, the conclusions are:(1)it could achieve the best effect when the perlite cover come to80g (2cm), and accordingly use83%of the evapotranspiration as plant transpiration;(2) the correlation coefficient between singleplant sap flow velocity(g/d) and actual transpiration velocity(g/d) was r=0.92, a-value and b-value of the equation was a=0.4463and b=8.3391;(3) the calibrated singleplant transpiration velocity (g/h) of three different water conditons on Nov.11st (heading stage)were:high1.10、middle0.75、low0.55; the calibrated singleplant transpiration velocity (g/d) of three different water conditons on Oct31st (heading stage)were:high26.51、middle17.13、low12.71.We used the universal formula of water flow through the soil-plant-systems to calculate the hydraulic resistance and also measured both leaf and soil potetial of soil-spring wheat system. The results showed:(1)leaf water potential showed that it was decreased first then increased during08:00-18:00, and leaf water potetial was high> middle> low soil water treatment during the same period of duration, and jointing stage> heading stage> filling stage under the same water treatment;(2)The soil water capacitance ratio under different water treatment in jointing stage were:high-2.49, middle-7.58, low-58.09;(3)transpiration velocity of spring wheat was high> middle> low soil water treatment during the same period of duration, and jointing stage> heading stage> filling stage under the same water treatment;(4)there was significant daily changes of hydraulic resistance in soil-plant system. It showed that the hydraulic resistances of SP system was middle> high water treatment in the same growing stage, and filling stage>heading stage>jointing stage under the same water treatment. The average hydraulic resistance(10Mpa·s·m-3) of SP system in a day in jointing stage was: high0.35, middle0.42; and the hydraulic resistance (109Mpa·s·m-3) of SP system during different period of duration under high water treatment was:jointing stage0.35, heading stage0.41and filling stage0.53.