遙測技術近年於農業領域廣泛應用，本研究探討‘42號’青花菜於節水栽培下之植生指數（vegetation index）變化。露天栽培於栽培槽，在營養生長期控制介質體積含水量（volume water content，VWC）於35％、25％及15％，當花芽創始之際停止處理。利用熱像儀記錄植體之葉冠溫度變化，以多光譜相機俯攝植株生長過程之光譜影像，並經過校正後計算植生指數。植生指數如NDVI（normalized difference vegetation index）、NDRE（normalized difference red edge index）、CCCI（canopy chlorophyll content index）、NDNG（normalized difference based on NIR and green reflectance）及OSAVI（optimized soil adjusted vegetation index）等，在種植第50天後VWC15％處理之NDVI、NDRE、NDNG及OSAVI表現顯著低於VWC35％及VWC25％。種植後第28天VWC15％處理之植體溫度表現顯著高於VWC35％及VWC25％，以同日測量的植生指數及經過測量當下氣溫標準化後的植體溫度進行迴歸分析後發現，各植生指數於處理間的差異與標準化後的葉冠溫度相關性隨種植天數增加，種植後第34天NDVI、OSAVI與經氣溫標準化後之葉冠溫度最早產生顯著相關R^2≧0.64。且在栽培期間，VWC35％及VWC25％之NDVI≧0.79，OSAVI≧1.18。因此，NDVI值為0.79，OSAVI值為1.18可成為檢測青花菜是否處於乾旱逆境之臨界指標，低於該值表示植物可能遭受水分逆境。節水栽培能提升青花菜的水分利用率，若配合使用植體溫度與植生指數，能快速取得作物之水分狀態，減少田間管理成本，更能精準提供作物所需之水分。

Remote sensing is widely used in agricultural field during recent years. This study explored the changes of vegetation indices of '42' broccoli under water-saving experiments. The broccoli seedlings were planted in open field in plastic containers under three different substrate volume water contents (VWC) at VWC35%, VWC25% and VWC15%. Thermographic camera was used to record the temperatures of plants, while multispectral camera was used to capture spectral images of plants growth. All treatments were terminated as floral initiation appeared. All the images were calibrated and used in calculating vegetation indices, including normalized difference vegetation index (NDVI), normalized difference red edge index (NDRE), canopy chlorophyll content index (CCCI), normalized difference based on NIR and green reflectance (NDNG), and optimized soil adjusted vegetation index (OSAVI). After planting 50 days, the vegetation indices of VWC 15% treatment were significantly lower than that of VWC35% and VWC25%. After planting 28 days, the temperature of VWC 15% treatment was significantly higher than that of VWC35% and VWC25%. The correlation between the difference of each vegetative index between treatments and the plant temperature of normalized by current temperature at the same day increased with the planting days. On the 34 day after planting, NDVI and OSAVI were significantly correlated with the earliest leaf canopy temperature after temperature normalization R^2≧0.64. And during the cultivation period, the NDVI of VCW35% and 25% were both higher than 0.79, and the OSAVI were also higher than 1.18. Therefore, the NDVI value of 0.79 and the OSAVI value of 1.18 can be the critical indicators for detecting whether broccoli is under drought stress. Water-saving cultivation can improve the water use efficiency of broccoli, and with the use of plant temperature and vegetation index, the water status of crop can be quickly obtained, the cost of field management can be reduced, and the water required by crops can be more accurately provided.