Abstract
The inheritance of the types of young plants which are prominent at the younger stage of development in wheat has been studied, with particular reference to some of the adult characters, in 4 successive generations from F1 to F4 of Hokuriku No. 13 with Saitama No. 27 crossing from 1938 to 1941.
The types of young plants were classified into five or six classes, T1-T5 or T6, from prostrate to erect by observation (c. f. Fig. 1).
The young plant type was intermediate in F1 between both parents. The distribution curve on the plant types of 390 F2 plants fairly resembled a normal curve as shown in Table 1. In 110 F3 lines descended from each class in F2 generation, various mean values (Type-values), which express the types of young plants in each line numerically, were observed as shown in Table 3. The result may be explained by two heteromeric major genes E1 and E2, which are imperfect in dominancy (c. f. Table 4-6 and Fig. 2).
In F4 generation, however, 17 families derived from each of 9 genotypes in F3 generation were grown, and the segregation was found more complicated than in F3 (c. f. Table 7). From this result it was assumed that the third gene E3, the effect of which being considerably weaker than the former two, should concern to the genic constitution of the young plant types. All F4 lines were successfully classified into 27 genotypes, which should theoretically result from the segregation of the three gene pairs (c. f. Table 8-10).
It may be concluded, therefore, that the types of young plants are controlled by three major heteromeries.
