Genetical Studies on Dense and Lax Panicles in Rice : II Character Expression and Mode of Inheritance of Dense Panicle Rice

Abstract

Following the previous paper (1979) dealt with the lax panicle rice, this investiga-tion was conducted to get information on the character expression of dense panicle rice and its mode of inheritance. It was found that the dense panicle cultivars and strains, in general, possessed either greater number of spikelets and panicle branches, or shorter panicle and primary branches than the normal type cultivar, the, causes for dense panicle being largely varied with the cultivars and strains tested. In some cultivars and strains which had extrerne dense panicles, the occurrence of tertiary branches was observed. It was verified that the newly devised method, that is, the ratio of total spikelets to total length of rachis and primary branches, by which the panicle density of normal and lax panicle rices would be satisfactorily esti.mated, as described in the previous paper (1979), could also be applied to the dense panicle rices. Crosses between a dense panicle mutant strain and its original cultivar. Akibare, and between the former and a dwarf mutant strain induced in Akibare were mad, e, and the segregations of panicle density and its related characters were investigated in F2. It was shown that the dense panicle mutant strain carried a single recessive gene respon-sible for the dense panicle, which was tentatively designated as dn. Positive gene interaction was also observed between the dense panicle gene and the dwarf gene