米粒白堊質之遺傳

Abstract

以包括親本與正反交組合之6 × 6 全互交Fl 材料探討水稻米粒白堊質之遺傳。白堊質米粒出現頻度與白堊質米白堊質面積大小等兩性狀之親本間之遺傳變異極大，此變異係由累加性與顯性效應所致。兩被評估性狀之狹義遺傳率值均高，指出兩性狀之表現型變異主由累加性效應控制。兩被評估性狀均存在有細胞質效應。其經迥歸與變方分析估得兩被評估性狀之顯性程度均屬部分或不完全顯性。而藉迥歸圖析及親本顯性次序之判定則指出白堊質米粒出現頻度中等者對出現少及多者為顯性；白堊質面積小者對大者為部分或不完全顯性。兩性狀親本間正負等位基因頻度不等，且顯性基因數多於隱性基因數。 The inheritance of two chalkiness characteristics of rice endosperm, the occurrence frequency and the opaque area of chalky endosperm were studied by means of a 6 × 6 diallel crosses including parents and reciprocal crosses. The genetic variations of two chalkiness characteristics of rice endosperm were significant among the parents. Both additive and dominance effects were important for two chalkiness characteristics. Furthermore, additive effects were significantly larger than dominance effects for two chalkiness characteristics. Estimated heritabilities for two chalkiness characteristics were very high indicating that a major portion of phenotypic variability was controlled by additive effects. Maternal effects existed in two chalkiness characteristics. Degrees of dominance for two chalkiness characteristics estimated by graphic and variance analysis showed partial or incomplete dominance. Directions of dominance evaluated by regression plotting and correlation coefficient between Yr and (Wr+Vr) were toward median occurrence frequency (ambidirection) and little opaque area of chalky endosperm. The average frequencies of positive and negative allels in parents were not equal and the number of dominant genes exceeded recessive genes for both chalkiness characteristics studied.