不同粒重水稻品種之農藝與生理性狀比較

Abstract

試驗採用大粒型水稻品種（千粒重約45g）Arborio 與中粒型品種臺農67 號（千粒重約25g）為材料，於民國72年第一、二期作在田間栽培，在水稻生育期間定期調查株高與分蘗數測定葉面積指數（LAI ）與乾物質累積之變化，並分析葉片內全氮與可溶性蛋白質之濃度，以比較不同粒重水稻。品種的農藝與生理特性，探討利用大粒品種之可行性。Arborio 幼苗具有極強的生長優勢，尤其在第一期作低溫與低日照環境下的生長極為快速，顯著優於臺農67 號，但其開始分蘗的時間較晚（移植後37 日），在一期作的分蘗期間僅有三週左右，故分蘗數較少，又由於有效分蘗百分比低，故穗數亦少於臺農67 號（分別為14 、21），可能為限制產量的主要因子。大粒型品種生育初期的株高增長較快，但成熟期之株高117cm 與臺農67 號113cm 差異不大。抽穗以前LAI 之變化受分蘗數之影響很大，亦以臺農67 號為高，Arborio 品種的LAI 多在4 以下，對乾物質生產有不利的作用。兩品種葉片內所含葉綠素濃度相近，但在抽穗以後，Arborio 之全氮與可溶性蛋白質濃度均較臺農67 號為高，唯向一時期穗重及全株乾重之增加反不如臺農67 號，且對抽穗前預貯物質之依賴較高。試驗結果建議分蘗數少與後期光合能力低落為大粒型品種Arborio 主要缺點，今後除應選取短稈與分蘗性強之大粒種源做為育種材料，對各項生理與栽培特性亦有詳加探討的必要。 One large-grain rice variety, Arborio (1,000-grain-weight of 45g), and one medium- grain variety, Tainung No. 67 (1,000-grain-weight of 25g), were used in this experiment. Some agronomic and physiological characteristics were determined during the growth course of the rice plants in both the first and second crop seasons. Seedling vigor of Arborio was significantly stronger than that of Tainung No. 67, especially under the conditions of low temperature and low solar radiation during the first crop of 1983. The initiation of tillering was late and the effective tillering duration was short for Arborio and hence the large-grain variety had fewer tiller number when compared with Tainung No. 67. Panicle number was also fewer for Arborio as a consequence of lower percentage of effective tiller. Leaf area index (LAI) before heading was strongly affected by tiller number. LAI of Arborio was generally below 4.0 and unfavorable effect on dry matter production was thus suggested. The two varieties contained similar chlorophyll concentration whereas Arborio had higher concentrations of total nitrogen and soluble protein, particularly during grain-filling. However, the dry weight increase of both panicle and total plant was inferior during the same period and the dependence of yield to preheading storage was more apparent for Arborio. Experimental results indicated that poor tillering ability and lower photosynthetic production during grain-filling were the major hindrances in utilizing large-grain varieties for commercial culture. Short-stat- ured, large-grain germplasm with more tiller number was suggested as useful breeding material in improving the yield potential of rice crop.