Abstract:

In order to provide a theoretical basis for developing orchards precision irrigation management, water vapor exchange and water use efficiency were monitored by an eddy covariance technique on an untilled 12-year-old peach orchard. The results showed that: a daily-average amount of evapotranspiration and WUE during monitoring stages were (2.3±2.1) mm/d and 1.26 g (CO2)/[kg (H2O)], respectively. The daily changes of WUE at canopy level were strongly influenced by ‘vapor pressure difference’ during the plant rapid growth stages. A from-high-to-low order of orchard-tree WUE followed the stages: post fruit harvest period>late fruit enlargement period and ripening period>flowering period and early fruit enlargement period. The trends of water evapotranspiration and WUE both had one peak. At the late period of fruit enlargement, the evapotranspiration was extremely high and reached its daily maximum value at 7.1 mm/d. Average daily WUE reached a peak of 2.1 g (CO2)/[kg (H2O)] after fruit harvest. The annually-cumulative evapotranspiration was up to 790.6 mm, and the annual average peach tree coefficient reached 1.08, which was higher 27% than that of FAO given. The results showed that the evapotranspiration at the peach-orchard-canopy level increased significantly under semiarid and sub-humid climate, and the key stage of water requirements on peach orchard was followed form late fruit enlargement period to fruit ripening period.