Sexual affinity between the lines derived from the intersubspecific hybrid and the ecotypes of rice plant

In a previous paper, the authors reported on the affinity between the lines derived from the intersubspecific hybrid of rice, Oryza sativa L., and their original parents. In short, most of these lines were thought to have returned to Japonica type parent, but some lines differed from their original parents and seemed to become a new type. To elucidate it more thoroughly, the authors produced the F1 hybrids between the 17 lines chosen at random from the progeny of the intersubspecific hybrid and the ecotypes of rice plant, Japanese rice, aus, aman, bulu, tjereh and boro, and investigated their seed fertilities. The results of the investigation lines were divided into two froups, “a” and “b”, according to sexual affinity between thses lines and the ecotypes. The lines of “a” group showed the highest affinity to Japanese rice, and moreover, the affinity to other ecotypes were similar to that between Japanese rice and other ecotypes. The authors considered form these results that the lines belonging to “a” group had returned to Japonica type parent. Three lines of “b” group were, on the other hand, thought to belong to intermediate tyoe grouped by morinaga, as they showed considerably high affinity to all ecotypes. They, however, differed from one another, and also differed from aus and bulu which were typical intermediate type. It gives us much interest in understanding the phylogenetic differentiation of cultivated rice varieties that the intermediate type was produced experimentally from Japonica-Indica hybrid.