Evaluation of Crop Coefficient, Cumulative and Dynamic Evapo-Transpiration of Winter Wheat under Deficit Irrigation Treatments in Weighing Lysimeter in Beijing, China

Abstract

The availability of water plays an important role in plant growth, yield and quality of crops In 2012-2013 experiment, Irrigation treatments were (1): Irrigation before sowing (60 Liter), (2): Irrigation before sowing (30 Liter) + before freezing (30 Liter); (3): before sowing (30 Liter) + before freezing (30 Liter) + in the beginning of erecting stage (60 Liter) + at flowering stage (60 Liter); (4): before sowing (30 Liter) + before freezing (30 Liter) + at booting stage (60 Liter) + at flowering stage (60 Liter). The weighing lysimeter system is located in National Precision Agriculture Demonstration Station in Xiaotangshang Town of Beijing. The maximum evapotranspiration value in March, April and May was obtained for lysimeter 10 (I2) (558.70 kg), lysimeter 11 (I3) (467.25 kg), and lysimeter 10 (I2) (488.68 kg), respectively. Knowledge about changes of soil water changes during successive growing seasons from planting to final ripening is a necessary tool for an effective planning of irrigation programs, in order to improve both quality and quantity of crop. From October to June, evapo-transpiration trends increased steadily, especially in last four months, in which the lysimeter fields were covered by winter wheat completely. In 2013-2014 experiment, Irrigation treatments were (1) no irrigantion, (2) irrigation only at jointing stage (60L), (3) irrigation at jointing (60L) and flowering stage (60L), (4) at jointing stage (April 8th, 60L), 100% flowering stage (April 30th, 60L), and grain filling period (May 10th, 60L) before irrigation, crop coefficient (KC) was low and exactly after irrigation, it increased and then it decreased gradually day by day. R2 between evapotranspiration which is on the basis of hourly weather data and daily weather data with measured ET in big lysimter was 0.962 and 0.953, respectively. Evapotranspiration and crop coefficient almost exactly match according to R2 of the regression. In conclusion, evapotranspiration and KC give a closer idea of the value of research on relationship between evapotranspiration and crop coefficient.