杏树蒸腾与降水和冠层微气象因子的关系

利用热扩散植物液流技术(TDP)测定时间步长10min的杏树蒸腾数据,结合同步观测到的降水量和果树冠层微气象因子值,分析华北低山丘陵区杏树蒸腾耗水规律及其与降水、微气象因子关系。结果表明:1)杏树蒸腾速率具有明显昼夜变化特征,在夜晚杏树蒸腾速率很低,白天随着太阳辐射强度的逐渐增加,气温逐渐升高,蒸腾速率逐渐增强;而后,太阳辐射强度减弱,温度降低,蒸腾速度减小。且在同一生长期内晴、多云天气日的蒸腾速率高于阴天天气日。2)杏树在生长季(4—9月)、非生长季(1—3月、10—12月)蒸腾耗水量分别为294.4、68.4mm,分别占全年的81.1%、18.9%。从4月起,杏树的蒸腾耗水量迅速增加,5月和6月达到全年的峰值,此后杏树耗水量逐渐减小。3)年际总降水与杏树蒸腾量的比值为1.6,大于1.0,周年降水可以满足杏树蒸腾耗水的需要,但供(降水量)求(蒸腾量)比各月间差异很大。4)回归分析表明:杏树在主要生长期内蒸腾速率与冠层净辐射、空气温度、湿度、风速等气象因子有很好的相关性(R2=0.833),各气象因子与杏树蒸腾速率的相关程度为冠层净辐射相对湿度空气温度风速。

Transpiration of apricot trees and their relationship with rainfall and canopy micrometeorological factors

In this study, transpiration of apricot trees and their relationship with rainfall and micrometeorological factors were investigated using thermal dissipation probe (TDP) technology combined with a micrometeorological system, which record data every 10 minutes. The results show that 1) transpiration rates (Tr) of apricot trees present typical diurnal characteristics, with low Tr at night. At daytime, Tr of apricot gradually increased with increases of irradiance and temperature and reduced with decreases of irradiance and temperature. The stock sap flow flux of apricot trees was higher on clear and cloudy days than on overcast days during the same growing season. 2) Daily Tr increased gradually from April and reached its peak during May and June, then fell gradually in July. Tr of apricot trees during the growing season (from April to September) and non-growing season (from January to March, and from October to December ) was 294.4 mm and 68.4 mm, accounting for 81.1% and 18.9% of the entire year, respectively. 3) The ratio of annual precipitation (R) to annual transpiration (R/T) was 1.6, higher than 1.0, which indicates that annual precipitation can satisfy the water use by transpiration of apricot trees at the experimental area. But the R/T varied significantly between months. 4) Regression results showed that Tr was significantly correlated with meteorological factors, such as net radiation (Rn), air temperature (ta), relative humidity (RH) and wind speed (v) (R2=0.833) during the main growing season. The degree of correlation of Tr and meteorological factors was Rn>RH>ta>v.