Estimation of evapotranspiration and crop coefficient of Chinese cabbage using eddy covariance in Northwest China

Abstract

Chinese cabbage is a key vegetable crop in northwest China. It is of great significance to study the evapotranspiration (ET) and crop coefficient (Kc) for agricultural water-saving management in this area. Eddy covariance (EC) was used to measure the ET and Kc of Chinese cabbage in northwest China from 1 May to 16 October 2020, in order to analyze the characteristics of these variables under plastic mulch. The results showed that the average Kc of the first crop of cabbage was higher in the middle and late stages, with values of 1.08 and 1.09 during the heading and maturity stages, respectively. The average Kc of the second crop of cabbage was higher in the middle stage, with values of 1.10 and 1.13 during the rosette and heading stages, respectively. The average annual Kc of Chinese cabbage was 0.81. Although Kc was higher in the middle and late periods, the water use efficiency was still 28.96 kg·ha−1·mm−1. The annual ET of Chinese cabbage was 505.3 mm. The study revealed the variation pattern of ET and Kc of Chinese cabbage, which provides an important scientific basis for the irrigation management of Chinese cabbage and is of great significance to guide the practice of water-saving vegetable planting.