荔枝树干液流速率与气象因子的关系

采用热扩散茎流仪于2011—2012年连续监测‘桂味’荔枝树干液流速率,将所得数据和果园内自动气象站观测数据一起进行对比分析,建立了液流速率与气象因子的关系模型。实验结果表明:(1)树干液流速率日变化呈现"昼高夜低"的规律。季节变化有呈现"先高后低"的趋势,整体上以果实发育期和成熟期(5—7月)液流速率较高。2011年年平均液流速率明显大于2012年;(2)树干液流速率日变化在晴天时多呈单峰曲线,且振幅较大;在雨天呈多峰曲线,且振幅较小。总体上,晴天平均液流速率约是雨天的两倍;(3)回归分析表明,在一定范围内,树干液流速率与太阳辐射强度、空气温度呈正相关,与空气湿度呈负相关。影响液流速率最重要的气象因子在晴天是空气温度,在雨天是太阳辐射。

Relationships between stem sap flow rate of litchi trees and meteorological parameters

The stem sap flow rates in "Guiwei" litchi trees and the meteorological conditions in the litchi orchard were observed continuously and synchronously from 2011 to 2012, using a Dynamax sap flow measuring system and an automatic weather station system, respectively. The temporal patterns of stem sap flow rates and the response to meteorological parameters were analyzed in order to establish a model of the relationship between these two variables. The principle results were as follows: (1) the stem sap flow rate followed a diurnal pattern, whereby rates were high during the day and low during the night. Seasonal variations in stem sap flow rates were observed, with higher average flow rates in the period of fruit maturation, from May to July. The average stem sap flow rate in 2011 was significantly higher than that in 2012. (2) On sunny days, the daily variation in stem sap flow-rate was characterized by a single-peak with a large amplitude of variation, while on rainy days the flow-rate was characterized by multiple peaks with a smaller amplitude of variation. On sunny days, the average value of stem sap flow-rate was twice as high as that on rainy days. (3) The regression equation based on stem sap flow rates and meteorological conditions showed that for a certain range of values, a positive correlation existed between the stem sap flow rates and solar radiation, and between the stem sap flow rates and air temperature, while a negative correlation existed between the stem sap flow rates and relative air humidity. On both sunny and rainy days, solar radiation and air temperature were the most important controls on stem sap flow rates, in terms of meteorological conditions.