Zhang Hengjia, Wang Zeyi, Yu Shouchao, Teng Anguo, Zhang Changlong, Lei Lian, Ba Yuchun, Chen Xietian
College of Agronomy and Agricultural Engineering, Liaocheng University, Liaocheng, China.
Yimin Irrigation Experimental Station, Hongshui River Management Office, Zhangye, China.
Front Plant Sci. 2023 Jun 16;14:1153835. doi: 10.3389/fpls.2023.1153835. eCollection 2023.
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 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 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.
为研究水分亏缺（WD）条件下绿洲西瓜的蒸散量和作物系数，在西瓜的各个生长阶段，包括苗期（SS）、伸蔓期（VS）、开花坐果期（FS）、膨大期（ES）和成熟期（MS），设置了轻度（田间持水量的60%-70%，FC）和中度（田间持水量的50%-60%，FC）水分亏缺水平，以生长季充足供水（田间持水量的70%-80%，FC）作为对照。在中国河西绿洲地区进行了为期两年（2020 - 2021年）的田间试验，以探究膜下滴灌条件下水分亏缺对西瓜蒸散特征和作物系数的影响。结果表明，日参考作物蒸散量呈锯齿状波动，与温度、日照时数和风速极显著正相关。西瓜整个生长季的耗水量在2020年为281 - 323毫米，2021年为290 - 334毫米，其中膨瓜期的阶段蒸散量最大，分别占总量的37.85%（2020年）和38.94%（2021年），其次依次为伸蔓期、苗期、成熟期和开花坐果期。西瓜的蒸散强度从苗期到伸蔓期迅速增加，在膨瓜期达到最大值5.82毫米·天，之后逐渐下降。苗期、伸蔓期、开花坐果期、膨瓜期和成熟期的作物系数分别在0.400至0.477、0.550至0.771、0.824至1.168、0.910至1.247和0.541至0.803之间。任何时期的水分亏缺都会降低该阶段西瓜的作物系数和蒸散强度。并且 与作物系数之间的关系可以通过指数回归更好地表征，从而建立了一个估算西瓜蒸散量的模型，其纳什效率系数在0.9以上。因此，绿洲西瓜在不同生长阶段的需水特征差异显著，需要结合各生长阶段的需水特点采取合理的灌溉和水分调控管理措施。此外，本研究旨在为寒冷干旱环境下沙漠绿洲膜下滴灌西瓜的灌溉管理提供理论依据。
