[Effects of annual distribution difference of precipitation on evapotranspiration characteristics of dry orchard in Loess Plateau, China]. / é»„åœŸé«˜åŽŸé™æ°´å¹´å† åˆ†å¸ƒå·®å¼‚å¯¹æ—±ä½œæžœå›­è’¸æ•£ç‰¹å¾çš„å½±å“.

Precipitation is the main driving factor for hydrological cycle in rain-fed agricultural areas, which determines the water-related ecological environment and affects the evapotranspiration characteristics of crops. By analyzing the annual distribution characteristics of precipitation across different years, this study clarified the concentrated trend of precipitation in Jingning County. Based on a field experiment in 2018 and 2019, the changes of soil moisture with precipitation and the response process of orchard evapotranspiration characteristics to the annual distribution differences of precipitation were explored. The results showed that the concentration degree of precipitation was high in the study area over the years. The concentration period was mainly distributed in July and August, with the proportion of August being up to 75%. Moreover, the time of precipitation concentration period varied greatly among years. The response of soil moisture to precipitation was mainly concentrated in the 0-40 cm layer, while moisture in deep soil layer would change significantly only in response to heavy and continuous rain. Both 2018 and 2019 were water-rich years. The precipitation concentration degree in 2018 was high, and the concentration period was earlier and shorter, with the diurnal water consumption of apple trees showing a single peak with large amplitude. In 2019, the distribution of precipitation was uniform, the concentration period was late, and the diurnal water consumption showed double-peak with a small amplitude and a lagged large peak. The maximum water demand period of apple trees lasted a long time. The concentrated distribution of heavy rain in 2018 could not meet the physiological water demands of apple trees in the later period, which damaged the yield, and the utilization efficiency of precipitation decreased by 30.2% compared with 2019. In the Loess Plateau region, there is often a brief drought during the young fruit growth period, which would affect fruit quality. Therefore, water management during this period should be strengthened.