利用環境參數評估花椰菜不同期作全生育期需水量

Assessing Water Requirements of Cauliflower Throughout Whole Growth Stages at Different Cropping Using Environmental Parameters

確定作物需水量為建立灌溉管理制的基本要件。本研究利用開放式水汽通量儀，透過渦流協變法量測蒸發散量構成因子，計算2022-2023年間共四期作花椰菜全生育作物蒸發散量（crop evapotranspiration, ETc），及配合氣象站感測資料，以Penman-Monteith法模式計算參考蒸發散量（potential evapotranspiration, ET0），進而求出作物係數（crop coefficient, Kc）。結果顯示2022/08-10、2022/12-2023/02、2023/04-06和2023/09-11四期作全生育期平均ETc分別為243、143、185及193 mm，平均Kc則分別為0.91、0.76、0.84及0.82，試驗期間Kc於定植後略呈現上升趨勢，偶有較高值，其值介於0.50到1.49，但與生育期和期作無顯著相關。此外，從田間水分收支計算之實際作物給水量與ETc比較，在現行慣性栽培方式下，每期作可再減少19%-114%灌溉水量的潛力，而滲漏計調查易受田區土壤狀態及農事操作干擾，較不適用於花椰菜此類短期作物。

Determining the water requirements of crops is essential for establishing irrigation management systems. In this study, an open-water flux instrument was used with the eddy covariance method to measure the component factors in the evapotranspiration of cauliflower. Potential evapotranspiration (ET0) was computed by the Penman-Monteith method according to the calculated crop evapotranspiration (ETc) and meteorological station data, then converted to crop coefficient (Kc) for cropping seasons from 2022 to 2023. The results showed that the average ETc during the four growing periods of cauliflower cultivated in 2022/08-10, 2022/12-2023/02, 2023/04-06, and 2023/09-11 were 243, 143, 185, and 193 mm, while plant Kc was 0.91, 0.76, 0.84 and 0.82 respectively. Kc showed a slight upward trend after planting during the trails, with occasional higher values ranging from 0.50 to 1.49. However, these values were not significantly related to the growth stages or cropping. Additionally, comparing crop water used in the field with ETc under current conventional cultivation practices through budget calculations, the amount of irrigation water can be reduced potentially by approximate 19%-114% for each growing season potentially. However, leakage measurements may be easily affected by soil conditions and agricultural practices, making them less applicable for short-term crops like cauliflower.