黄土塬区小麦茎流速率变化及其与环境的关系

Relationship Between Wheat Sap Flow Velocity and Environmental Factors on Loess Tableland

利用Dynamax茎流测量系统和自动气象站分别对黄土塬区小麦(陕麦150)拔节期和开花期的液流变化及其周围气象环境因子变化进行了监测。结果表明:(1)两个时期小麦茎流速率日变化趋势基本相同,为单峰型;液流启动时间分别为早晨7:00—8:00和6:00—7:00,在中午12:00—14:00左右达到各自峰值,其值大小分别为1.90和2.66g/h(4月24日和25日,晴天,拔节期),3.39和2.96g/h(5月18日和19日,晴天,开花期),21:00左右降到最低,夜间无明显液流;晴天茎流速率明显大于阴天。(2)不同时期茎流速率日变化与环境因子日变化紧密相关。相关分析显示,影响小麦茎流变化的主要因子是光合有效辐射、大气温度、湿度和风速等;其中,湿度与茎流速率负相关。

The daily sap flow velocity of wheat was measured using Dynamax Flow 32 and the environmental factors were monitored using Automatic Weather Station System at the jointing and flowering stages. The relationships between sap flow velocity and environmental factors were also analyzed. Results showed that （1） the curve for diurnal variation of sap flow had a peak. The trend was the same at jointing and flowering stages. Sap flows at the two stages started at 7：00--8：00 and 6：00--7：00, respectively. The maximum sap flow velocity was observed at 12：00--14：00, and the values were 1.90 and 2.66 g/h （24th and 25th, April, sunny day, jointing stage） and 3.39 and 2.96 g/h （0518 and 0519, sunny day, flowering stage）, respective- ly. Then the sap flow velocity dropped clown to the lowest at 21：00 and no sap flow was observed at night. The value of sap flow on sunny day was higher than that on cloudy day. （2） There was a similar trend be- tween sap flow velocity and environmental factors. The relationships among them were significant. There was a negative significant correlation between sap flow velocity and humidity, while it showed positive corre- lations with other environmental factors. From correlation analysis, their coefficients were in the order of photosynthetically active radiation 〉 air temperature 〉 humidity 〉 wind speed.