(36(2):125-136)Genetic Studies on Larger Kernel Size of Rice- Ⅲ. Inheritance of Grain Yield, Biological Yield and Harvest Index

以 Griffing 及 Jinks-Hayman 氏等兩套全互交分析方法，分析包括親本與正反交組合之 9 × 9 全互交材料，以探討水稻單株穀產量、生物產量及收穫指數之遺傳行為。此三個性狀親本間之遺傳變異均極大，此變異係由累加性與顯性效應所引起，除收穫指數為累加性效應約等於顯性應外，餘 2 性狀之顯性效應均顯著地大於累加性效應。三個性狀之一般組台力與特殊組合力效應均存在，而一般組合力又較特殊組合力重要，其比率約為 4:1。被報告三性狀均發現有細胞質效應。經由迴歸與變方分析估得三性狀之顯性程度為超顯性。正負等位基因在親本間之分佈三性狀均不等。單株穀產量及收穫指數等兩性狀之顯性基因數等於隱性基因數；而生物產量之顯性基因數則多於隱性基因數。經藉迴歸圖析及親本顯性次序判定，指出穀產量少者為顯性，餘兩性狀之顯性方向為雙力向。估得三性狀之狹義遺傳率均低。 The inheritance or grain yield, biological yield and harvest index for larger kernel size or rice were studied by mean of a 9 X 9 diallel crosses including parents and reciprocal crosses. Date from the F1 generation and parents were analyzed using the Griffing and the Jinks-Hayman methods of diallel analyses. The genetic variations of these three traits were significant among the parents. Both additive and dominance effects were important for all these traits. Furthermore, dominace effects were signif i- cantly larger than additive effects for these traits except that for harvest index that additive and dominance effect was about equal. Highly significant general combining ability (GCA) and specific combining ability (SCA) effects were observed for these traits. The GCA effects were more important than SCA effects, the ratio being 4:1. Maternal effects existed in all these traits. Degrees of dominance of all these traits estimated by graphic and variance analyses showed over-dominance. The average freque-ncy of positive and negetive allel in parents were about equal for all traits. Number of dominance genes exceeded recessive genes for biological yield. Onthe other hand, both number of dominance and recessive genes were equal for grain yield and harvest index. Directions of dominance evaluated by regression plotting and correlation coefficient between Yr and (Wr±Vr), were toward lower grain yield for grain yield and ambi-directions for biological yield and harvest index. Estimated heritabilities for all these traits were low