Crop coefficient determination and evapotranspiration estimation of watermelon under water deficit in a cold and arid environment

Hengjia Zhang; Zeyi Wang; Shouchao Yu; Anguo Teng; Changlong Zhang; Lian Lei; Yuchun Ba; Xietian Chen

doi:10.3389/fpls.2023.1153835

Crop coefficient determination and evapotranspiration estimation of watermelon under water deficit in a cold and arid environment

Front Plant Sci. 2023 Jun 16:14:1153835. doi: 10.3389/fpls.2023.1153835. eCollection 2023.

Authors

Hengjia Zhang¹, Zeyi Wang¹, Shouchao Yu¹, Anguo Teng², Changlong Zhang², Lian Lei², Yuchun Ba², Xietian Chen³

Affiliations

¹ College of Agronomy and Agricultural Engineering, Liaocheng University, Liaocheng, China.
² Yimin Irrigation Experimental Station, Hongshui River Management Office, Zhangye, China.
³ College of Water Conservancy and Hydropower Engineering, Gansu Agricultural University, Lanzhou, China.

Abstract

To investigate the evapotranspiration and crop coefficient of oasis watermelon under water deficit (WD), mild (60%-70% field capacity, FC)and moderate (50%-60% FC) WD levels were set up at the various growth stages of watermelon, including seedling stage (SS), vine stage (VS), flowering and fruiting stage (FS), expansion stage (ES), and maturity stage (MS), with adequate water supply (70%-80% FC) during the growing season as a control. A two-year (2020-2021) field trial was carried out in the Hexi oasis area of China to explore the effect of WD on watermelon evapotranspiration characteristics and crop coefficient under sub-membrane drip irrigation. The results indicated that the daily reference crop evapotranspiration showed a sawtooth fluctuation which was extremely significantly and positively correlated with temperature, sunshine hours, and wind speed. The water consumption during the entire growing season of watermelon varied from 281-323 mm (2020) and 290-334 mm (2021), among which the phasic evapotranspiration valued the maximum during ES, accounting for 37.85% (2020) and 38.94% (2021) in total, followed in the order of VS, SS, MS, and FS. The evapotranspiration intensity of watermelon increased rapidly from SS to VS, reaching the maximum with 5.82 mm·d^-1 at ES, after which it gradually decreased. The crop coefficient at SS, VS, FS, ES, and MS varied from 0.400 to 0.477, from 0.550 to 0.771, from 0.824 to 1.168, from 0.910 to 1.247, and from 0.541 to 0.803, respectively. Any period of WD reduced the crop coefficient and evapotranspiration intensity of watermelon at that stage. And then the relationship between LAI and crop coefficient can be characterized better by an exponential regression, thereby establishing a model for estimating the evapotranspiration of watermelon with a Nash efficiency coefficient of 0.9 or more. Hence, the water demand characteristics of oasis watermelon differ significantly during different growth stages, and reasonable irrigation and water control management measures need to be conducted in conjunction with the water requirements features of each growth stage. Also, this work aims to provide a theoretical basis for the irrigation management of watermelon under sub-membrane drip irrigation in desert oases of cold and arid environments.

Keywords: leaf area index; meteorogical factors; reference crop evapotranspiration; water consumption characteristics; water stress; watermelon.

Grants and funding

This work was funded by the National Natural Science Foundation of China (no. 52269008, 51669001), the Industrial Support Plan Project of Gansu Provincial Department of Education (no. 2022CYZC-51), the Discipline Team Construction Project of Gansu Agricultural University (no. GAU-XKTD-2022-07 GAU-XKTD-2022-07), and the Key Research and Planning Projects of Gansu Province (no. 18YF1NA073).