紫花苜蓿冠气温差与蒸腾速率变化规律的试验研究

Experimental Study on Variation of Canopy-air Temperature Difference and Transpiration Rate of Alfalfa

本文主要研究不同水分处理条件下紫花苜蓿冠气温差和蒸腾速率的变化规律。结果表明,全生育期内,冠气温差和蒸腾速率变化规律基本一致,各典型日两者日变化趋势基本呈现"M"型。当灌水下限较高时,冠气温差基本呈负值且日变化和蒸腾速率较一致;当灌水下限较低时,冠气温差基本呈正值,蒸腾速率较小且日变化幅度较平缓。冠气温差较小时,随冠气温差增大蒸腾速率呈上升趋势,而当冠气温差大于0℃以后,随冠气温差增大蒸腾速率不再增加,甚至出现一定的下降趋势。

This paper mainly studied the variation of canopy-air temperature difference and transpiration rate of alfalfa under different water conditions. The results showed that the change law is basically identical of canopy-air temperature difference and transpiration rate in the whole growth period, and there are ‘ M’ model in the typical day for the shape of the diurnal variation curve. The canopy-air temperature difference is negative and that diurnal variation curve is basically identical with transpiration rate＇s under full irrigation, while the canopy-air temperature difference is positive, the transpiration rate is lower and the variation is smoother with larger deficit. Transpiration rate increases with the increase of canopy-air temperature difference when it is smaller and the transpiration rate decreases when canopy-air temperature difference is greater than 0℃.