Applicability evaluation of TDP method in the aspect of transpiration of 5 bamboo species

Abstract:

This study was undertaken to establish an optimal and reasonable design for TDP method to be used in bamboo water use owning to the special structure of bamboo species. By using the method of combining water-injection induced hydraulic pressure and sap flow changing device together with whole-plant container weighing in verifying the Granier empirical formula and calibrating the coefficient. In addition, we observed structure of vascular bundle in 5 bamboo species (Phyllostachys edulis、Bambusa chungii、Bambusa textilis、Arundinaria amabilis、Bambusa vulgaris). Vascular bundles were randomly scatted across the culms in uneven. Development degree of vascular bundles was different which vascular bundles close to the inside of clum were better than outside. Vascular bundles close to the inside of culm had better transporting water capability than outside. In the cut bamboo experiments, we found that Fd and K followed a power function and all the R2＞0.83. This suggested TDP method was an applicable technique for assessing sap flow density in bamboo species. Furthermore, whole-plant container weighing method corrected the equation coefficients and gained the new sap flow formula for every bamboo kind. The new sap flow formula was different from the Grnaier empirical formula which a was several times more than original a. The daily transpiration calculated by new equation and Granier empirical formula had a significant difference, especially during the peak hours (at noon) of sap flow in one day . Our study concluded that as long as the TDP method is carefully verificated and Granier empirical formula is corrected, then TDP method is an applicable technique for assessing water use in bamboo species.

Key words:structural heterogeneity;Granier empirical formula; calibration coefficient;vascular bundle structure