利用熱量單位建構水稻主要生育期栽培歷程之研究

水稻(Oryza sativa L.)為世界三大的糧食作物之一，栽培過程受溫度的影響甚鉅。作物生長受溫度影響的發育模式研究始於熱量單位，作物的生長若達到特定生育期時，需累積到一定的熱量單位。因此，將各生育期溫度的影響量化為熱量單位，以利判斷作物的生育期。本試驗的研究目的為建立國內四個重要的水稻品種(「台稉9號」、「台農71號」、「台南11號」及「高雄147號」)，在五個重要生育期(50%始蘗期、最大分蘗期、幼穗分化期、50%抽穗期及生理成熟期)熱量單位累積的範圍，並修正各品種最適合的基礎溫度。本試驗的結果指出，各品種適合的基礎溫度分別為：台稉9號為6.4℃(43.52℉)、台農71號與台南11號均為6.6℃(43.88℉)及高雄147號為7.6℃(45.68℉)。依各生育期累積的熱量單位於兩期作間變異係數較低，推薦台稉9號、台農71號與台南11號三個品種，可利用基礎溫度修正後GDD與DD50min>70℉的熱量單位，預估水稻重要的生育期，而高雄147號則推薦以GDD(Tb=7.6℃)與DD50min>70℉(Tb=50℉)的熱量單位。利用GDD累積熱量單位之95%信賴區間，預估高雄147的幼穗分化期，所預估的誤差僅0-2天。期望各品種以推薦的熱量單位代替栽培曆的生育日數，以準確預測水稻之最大分蘗期與幼穗分化期的生育期，作為栽培管理與肥料施用時期的參考指標。

關鍵字

熱量單位；基礎溫度；曬田期；幼穗分化期；預估生育期

並列摘要

Rice (Oryza sativa L.) is one of the world’s three major food crops, and also the most important staple food in Taiwan. The rate of biological processes of rice are greatly influenced by temperature, and the timing of development stages could be quantified and predicted through heat accumulation. Therefore, the heat units concept was applied in this study, which were expressed in growing degree-days (GDD) and degree-days 50 (DD50), to characterize the development stages of rice. The objective of this study was to determine the required amount of accumulative heat units during the 50% tillering, maximum tillering, panicle initiation, and physiological maturity stages following with the revised base temperature for the four major cultivars (TK9, TNG71, TN11, and KH147) in Taiwan. The analysis results indicated that the appropriate base temperature for each cultivar is 6.4°C (43.52℉) for TK9, 6.6°C (43.88℉) for TNG71 and TN11, and 7.6°C (45.68℉) for KH147. Considering the lowest coefficient of variation of the heat units both at the first and the second crop season, DD50min>70with modifying base temperature (43.52℉, 43.88℉, 43.88℉) was recommended to be applied on TK9, TNG71, and TN11. On the other hands, KH147 was suited to GDD (Tb=7.6°C) and DD50min>70(Tb=50℉). The 95% confidence interval of GDD was applied to predict the panicle initiation stage of KH147 within 2 days. For the purpose of accurate prediction of maximum tillering and panicle initiation stages, the heat units with modified base temperature in this study are worth popularizing to substitute the traditional calendar days. GDD and DD50 in this study could be the useful indicators for the optimization of field management and timing of nitrogen fertilizer topdressing.