Study On Water Consumption Of Cherry And Peach Trees And Evapotranspiration Estimation Methods Under Deficit Irrigation In Beijing

Due to drought climate and scarce water resources in North China Plain, there were many problems in irrigation management on fruit tree in this region. Therefore, according to the physiological requirements of plants for water and the characteristics of water consumption of fruit trees, an appropriate irrigation scheme on orchard is necessary so as to provide theoretical basis to improve fruit yield and quality as well as water utilization efficiency.Plot experiments were conducted continuously in an orchard of Tongzhou, Beijing, from 2011 to 2013. Water consumption, growth and development, the yield and quality of cherry and peach trees under different degrees of water deficit were obtained by using drainage lysimeter, thermal dissipation probe method, and soil water automated monitoring system. In addition, evapotranspiration (ET) estimation methods were also studied according to local meteorological data and empirical models. The main results are outlined as follow:(1) Annual ET0 calculated by various methods (Penman-Monteith (PM), Hargreaves-Samani (HS), Blaney-Criddle (BC), Makkink, and FAO-Radiation (FAO-rad)) showed a significant decline trend in the past 57 years and monthly ET0 showed a trend of increasing first and then decreasing. FAO-rad method was satisfactory to estimate monthly and annual ET0 while BC method was not. HS and FAO-rad methods can be used for ET0 evaluation in the conditions of lacking meteorological data in North China Plain.(2) The influence degree of meteorological factors on ET2 was as follows:relative humidity> air temperature> wind speed> sunshine hours. The negative contribution of relative humidity to ET0 trend was greater than the positive contribution of temperature, causing ET0 to decrease.(3) Soil moisture content had a large fluctuation on the layer of 0-20 cm and little change on 80-130 cm. Daily soil evaporation showed a trend of increasing first and then decreasing in the growth period and had an average of 1.32 mm·d-1, positively correlated with radiation and temperature but negatively correlated with relative humidity. Variation amplitude in soil temperature decreased with the increase of soil depth. Soil temperature had a large fluctuation on the layer of 0-20 cm and less change below 60 cm. Film mulching increased soil temperature for all layers and decreased difference between day and night, especially in top soil.(4) The diurnal variation of sap flow rate of fruit tree appeared a single-peak curve of increasing first and then decreasing, which was positively correlated with radiation and temperature, and negatively correlated with relative humidity. Daily sap flow also showed the same trend in the whole growth period, which was influenced by different irrigation amounts or plastic film mulching. Daily evapotranspiration of all treatments showed a single-peak trend of increasing first and then decreasing in the whole growth period. The control treatment (Full irrigation, FI) of cherry and peach trees both obtained the maximum evapotranspiration, which was 567 and 556 mm, respectively.(5) The leaf area index of fruit tree showed a single-peak trend of increasing first and then decreasing in the whole growth period, and was increased under high moisture or film mulching. Net photosynthetic rate, stoma conduction, and transpiration rate all increased first and then decreased in daytime, which can obtain maximum values under moderate water stress (2/3 FI). Both moderate water stress and film mulching obtained a higher yield and water use efficiency, and they did not adversly affect fruit quality.(6) The relative error of total evapotranspiration in whole growth period calculated by dual crop coefficient approach was less than 4.5% as compared with the measured values by sap flow-micro lysimeter or water balance methods. By calculation and analyses on the ratio of root-mean-square error to the standard deviation of measured data (RSR) and the Nash-Sutcliffe efficiency (NSE), it can be concluded that dual crop coefficient approach is an effective method to calculate evapotranspiration amount and crop coefficient of fruit tree under full irrigation in North China Plain.