本研究比較不同作物種類（水稻、玉米及甘藷）、土壤水分差異（水、旱田）及種植時期（春、秋作）之農田通量與微氣象因素之間的關聯性。利用渦流相關偵測系統記錄作物整個生育期之通量資料。研究結果顯示，水稻田因湛水狀態使空氣溼度較高，水蒸氣壓差(VPD)偏低，水稻田之潛熱通量明顯高於顯熱通量。三種作物之CO2及潛熱通量與輻射量有線性正相關，水稻及玉米相關係數在0.7以上，甘藷田較低約為0.5。輻射利用效率(RUE)與溫度之間的關聯性在三種作物間有不同反應，水稻在溫度範圍為24-32℃間之RUE與溫度成反比：玉米雖呈反比趨勢，但對溫度反應不大，幾乎呈定值；甘藷田RUE與溫度成正比，可能與秋作低溫有關。三種作物之水分利用效率(WUE)與VPD皆呈負相關。WUE在植冠受光照後開始有明顯高值，在光照強度約為1,000 μmol m^(-2) s^(-1)時開始呈穩定。
This study was to compare the relations of microclimate factors with eddy fluxes from different farming conditions varying in crops (rice, corn and sweet potato), soil water status (paddy and upland) and planting seasons (Spring and Autumn). The eddy correlation system was setup above crop canopy to record the flux data during crop growth. Results indicated that relative humidity was higher and vapor pressure deficit (VPD) was lower in rice paddy field due to the submerged condition. In addition, latent heat flux was higher than sensible heat in energy balance. The relationship between CO2 flux and radiation flux was a linear fashion in three crops. The correlation coefficient for paddy rice and corn was above 0.7 and was about 0.5 for sweet potato. The relationship between radiation use efficiency (RUE), defined as the ratio of CO2 flux to photosynthetic photon flux density, and temperature varied in crops. RUE was negatively correlated with temperature in the range of 24-32 ℃ in rice, and was also negatively correlated in corn. However, positive relationship was observed in sweet potato owing to low temperatures. The water use efficiency (WUE), defined as the ratio of CO2 flux to latent heat flux, was negatively correlated with VPD in three crops. The values of WUE increased after sun rise and remained in a stable condition at light intensity over 1, 000 μmol m^(-2) s^(-1).
