利用光合测定系统对夏玉米灌浆前期叶片水汽交换的参数进行了系统测定,得出叶片净光合速率、蒸腾速率、叶片温度、气孔导度与水分利用效率的关系。结果表明,3种水分处理的净光合速率、蒸腾速率和水分利用效率都有大体一致的日变化过程,但又体现了不同水分处理的差异性。胁迫处理的水分利用效率大于湿润处理和干旱处理。水分利用效率与净光合速率、蒸腾速率的关系有很大的相似性,当净光合速率<20μmol/m~2·s时,水分利用效率基本无变化,当20μmol/m~2·s<净光合速率<26μmol/m~2·s时,水分利用效率增长最快;当蒸腾速率<5mmol/m~2·s时,水分利用效率变化不大,在5mmol/m~2·s<蒸腾速率<7mmol/m~2·s时,水分利用效率增长最快;当净光合速率>26μmol/m~2·s和蒸腾速率>75mmol/m~2·s时,水分利用效率均呈现下降趋势。水分利用效率对叶片温度有很强的敏感性,在40℃<叶片温度<42℃时,水分利用效率迅速增加。随气孔导度的增大,水分利用效率呈上升趋势,在140mmol/m~2·s<气孔导度<200mmol/m~2·s时,水分利用效率上升最快,气孔导度再增大时,水分利用效率趋于稳定甚或下降。 The photosynthesis system was used to measure the leaf water vapor exchange parameters of summer maize before filling. The relationships between net photosynthetic rate, transpiration rate, leaf temperature, stomatal conductance and water use efficiency were obtained. The results showed that the net photosynthetic rate, transpiration rate and water use efficiency of the three kinds of water treatments all had a generally consistent diurnal course, but they also reflected the differences of different water treatments. Water use efficiency of stress treatment was higher than that of wet treatment and drought treatment. There was a great similarity between the water use efficiency and the net photosynthesis rate and transpiration rate. When the net photosynthesis rate was less than 20μmol / m ~ 2 · s, the water use efficiency basically remained unchanged. When the net photosynthesis rate was 20μmol / m ~ 2 · s When the photosynthetic rate was less than 26μmol / m ~ 2 · s, the water use efficiency increased fastest. When the transpiration rate was less than 5mmol / m ~ 2 · s, the water use efficiency did not change much. Under the condition of 5mmol / m ~ 2 · s When the net photosynthetic rate was> 26μmol / m ~ 2 · s and the transpiration rate was> 75mmol / m ~ 2 · s, the water use efficiency showed a downward trend. Water use efficiency has a strong sensitivity to leaf temperature. Water use efficiency rapidly increases when leaf temperature is below 42 ℃ at 40 ℃. With the increase of stomatal conductance, water use efficiency showed an upward trend. Water use efficiency increased fastest and stomatal conductance increased at 140 mmol / m ~ 2 · s