应用热扩散法测定香蕉树蒸腾速率

香蕉树植株高大，一般采用间接方法确定耗水量，但所得结果受土壤、大气和农艺措施等因素的影响较大.本文于2005年11月15日—12月5日在温室内采用热扩散法（即Granier法）测定香蕉树的茎液流，并与用数字天平（称重法）测定的香蕉树蒸腾速率进行对比试验. 结果表明，Granier法测定的日茎液流量与称重法测定的日蒸腾量相差4％.Granier法测定的茎液流速率一般滞后于称重法确定的蒸腾速率1 h左右.当日蒸腾量小于0.05 L·m^-2（活性叶面积）时，Granier方法不能测定茎液流量.Granier传感器一般在安装2～3 d后即可正常工作，同时在多株植株上安装Granier传感器取其平均流速值计算蒸腾量可以明显减小测量误差.

Transpiration of banana plant measured by Granier method

Banana plant is the highest herbaceous plant in the world. Because of the height, it's inconvenient to measure the transpiration (Tr) of banana plant in direct way. Some indirect methods such as soil water balance method or FAO 56 Crop Coefficient are commonly used to measure or calculate the Tr, but the obtained results are easily influenced by soil texture and water content, climatic condition, and agronomic practice. In the present paper, Granier method was used to measure the sap flow (SF) at the corm of banana in a greenhouse from November 15 to October 5, 2005, with the Tr measured by gravimetric method compared. The results showed that the daily SF measured by Granier method was about 4% lower than the daily Tr measured by gravimetric method, and the SF rate lagged the Tr rate about one hour. Granier method was not sensitive enough to measure SF when the daily Tr was less than 0.05 L x m(-2) active leaf area. Granier probes could work properly 2-3 days after installation, and the measurement error of Granier method could be much reduced when more sets of probes were installed and the mean values of SF rate were taken.