The Effect of Effective Heat Unit on Leaf Number Expression of Rice

Abstract

本試驗以25個逢機選取自台灣地區過去育成的水稻品種爲材料，於1995年二期作 及1996年一期作進行田間試驗調查，探討有效熱單位對水稻葉齡表現之影響。試驗結果顯示一期作因葉片伸展期之氣溫較低，水稻達到劍葉抽出之日數較二期作爲長，但若以有效累稂熱單位表達，則一期作達劍葉抽出所需之量較二期作低。唯在兩期作中，移植後初期，及葉片伸展後期之單位葉齡及葉齡指數所需之有效累積熱單位較其它時期爲高。另分析不同生長期單位葉齡及葉齡指數伸長所需之有效累植熱單位，結果顯示兩期 作之生殖生長期均較營養生長期爲高，唯在期作間，營養生長期所需之有效累積熱單位 於二期作較一期作爲高，但生殖生長期則無顯著差異。 Twenty-five varieties were used to study the effect of effective heat unit on leaf number expression of rice. Effective heat unit sumlation (EHUS) of rice plants reached to flag leaf expansion in the 1st crop season were obviously lower than those of rice in the 2nd crop season. EHUS of early and late period of rice leaf expansion on per leaf number (LN) and leaf number index (LNI) were higher than other stages. Rice plants in reproductive growth period of the 1st and the 2nd crop seasons seemed to require higher EHUS for leaf expansion. While in the vegetative growth period of the 2nd crop season, the EHUS requirement for leaf expansion seemed higher than those of the 1st crop season