Comparison of the portable steady porometer method and standard branch soaking method for the measurement of poplar's water consumption by transpiration

In order to use the standard branch soaking method to calibrate the rate of water consumption by the portable steady porometer method to measure transpiration,the rates of water consumption by transpiration eight 4-year-old poplar clones were measured by a portable steady porometer method and standard branch soaking method in the nursery garden of the forestry bureau of Gaomi City in May,2008.The results showed that the rate of water consumption by transpiration measured by these two methods for a daily changing tendency was a single-apex curve.The rate of water consumption by transpiration measured with the portable steady state porometer method was always higher than the standard branch soaking method.The difference of the ratios of measured value between the two methods was not obvious when the transpiration rate was lower in the morning and evening,but the difference increased with relative humidity decreasing,and the light,temperature and transpiration rate increasing.The rate of water consumption by transpiration was linear by these two measured methods,(correlation coefficient,R20.8),and the correlation was significant.This study can be used to correct the poplar's water consumption by transpiration measured by the portable steady porometer method.