热消散法(TDP)在5种竹子蒸腾耗水测定中的适用性评价

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

摘要:

利用室内离体竹段注水变压法结合野外整株容器称重法对Granier公式进行验证和系数校正。并观察了5种竹子(毛竹Phyllostachys edulis、粉单竹Bambusa chungii、青皮竹Bambusa textilis、茶秆竹Arundinaria amabilis、龙头竹Bambusa vulgaris)茎秆维管束结构。结果发现：茎秆维管束分布不均，维管束发育程度从竹壁外向内逐渐成熟，输水能力也逐渐增强。室内实验中液流密度(Fd)和液流指数（K）值呈幂函数关系，相关系数R2＞0.83，说明热消散探针方法能较好地反应竹类的液流密度。用整株容器称重法对推导出的液流公式校正后得到适于5种竹子的液流密度公式。校正后液流密度公式与原始Granier公式各系数均不同，其中a值更是超出原始公式几倍多。公式校正前后计算的日蒸腾量差异显著，尤其是在一天中液流高峰时段（午间）差距最大。结论表明只要对热消散探针方法准确验证、对Granier原始公式系数给以校正，那么TDP技术是估计竹类植物水分利用的一种适宜方法。

关键词:结构异质性;Granier经验公式;校正系数;维管束结构

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