Application and calibration of sap flow gauge in spring wheat transpiration

This study aimed at evaluating the transpiration characteristics of potted spring wheat using a sap flow method designed by a heat balance technique under three different water treatments(high 85%～75%,middle 65%～55% and low 45%～35%) calibrated using a weighing method.The results showed that:(1) the treatment with the perlite cover of 0.11 g/cm2 is better than the others.Under this condition,the spring wheat transpiration accounts for 83.04% of the total evapotranspiration;(2) the single wheat sap flow rate was strongly correlated with the transpiration rate at the daily scale with the correlation coefficient of 0.92,and slope and intercept of 0.4463 and 8.3391,respectively.Similarly regressive results were also obtained at the hourly scale.(3) Taking Oct.31st,2012 as an example,the calibrated single plant transpiration rate were 26.51 g/d,17.13 g/d and 12.71 g/d,respectively,under three water conditions ranked from high to low.Overall,this study indicates,while determining the transpiration of field crops,it was necessary to calibrate the transpiration rate by sap flow method.