WEI Zheng 1, 2, XU Di 1, LIU Yu 1, CAI Jia-bing 1, 2

1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China;
2. National Center of Efficient Irrigation Engineering and Technology Research, Beijing 100048, China

Abstract: Based on the field trial data of winter wheat of two growing seasons, this study revealed the response relationship between the canopy-air temperature difference and multi-factors, and expounded the influence of canopy-air temperature difference to leaf photosynthetic rate and transpiration rate. Furthermore, the canopy-air temperature difference and relative canopy-air temperature difference thresholds on leaf photosynthetic rate and transpiration rate were obtained. The results show that the winter wheat canopy-air temperature and saturated vapor pressure difference are significantly negatively correlated. The photosynthetic rate, transpiration rate and canopy-air temperature difference are presented significantly quadratic parabolic relation. The regulatory threshold of winter wheat leaf water use efficiency and water deficit diagnosis could be reflected by the different interval of canopy-air temperature difference and the relative canopy-air temperature difference to leaf photosynthetic rate and transpiration rate. In different hydrological years, at different growth stage (heading to flowering, filling stage and mature stage), the relative canopy-air temperature difference interval are 0.40-0.60, 0.40-0.55 and 0.40-0.65.

Key words: winter wheat; canopy air temperature difference; water deficit diagnosis; regulation of soil moisture; water year

Published in: Journal of Hydraulic Engineering, Vol. 45, No. 8, 2014