华北粗砂土免耕桃园生态尺度水分利用效率研究

为了给制定果园精准灌溉管理方案提供理论依据，采用涡度相关技术，监测并探讨粗砂土立地条件下12年树龄自然生草免耕桃园生态尺度水分耗散及水分利用效率的动态变化。结果表明，桃园全年监测期内，日平均蒸散耗水量和水分利用效率分别为(2.2±2.1) mm和0.44 g/kg，饱和水汽压差是影响桃树旺盛生长季日水分利用效率的关键因子，群体水平日平均水分利用效率由高到低的顺序为：果实收获后＞果实成熟期与果实膨大后期＞果实膨大初期与开花期；季节变化过程中，蒸散耗水量和水分利用效率均呈单峰型变化趋势，在果实膨大后期至成熟期蒸散耗水量较多，且日最高蒸散量达到7.1 mm，日平均水分利用效率则在果实收获后达到高峰，日平均水分利用效率最高为2.1 g/kg；全年累积蒸散耗水量为790.6 mm，平均作物系数(Kc=1.08)高于FAO(1998)推荐值达27%。果实膨大后期-成熟期是桃树水分耗散高峰期，采取精准灌溉等措施进行果园水分科学管理是提高果树水分利用效率的关键。

Canopy Water Use Efficiency on a Coarse-Sand-Field, No-Tillage Peach Orchard in North China

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.