Character expression of a rice dwarf mutant with lax panicle

摘要

A dwarf mutant with lax panicle was induced from the parent cultivar Fujiminori by 200 Gy of X-ray irradiation. The mutant exhibi ts leaf rolling during the early vegetative phase until the appearance of the 6th or 7th leaf. Inheritance of this mutanttrait was studied from an F_2 segregation involving a cross between the dwarf mutant and the parent cultivar. The F_1 was normal and the F, segregated into 103 normal plants and 39 dwarf plants, giving a good fit to a 3:1 ratio (x~2 =0.460, P=0.498). Pleio-tropic action of the dwarf mutant gene appears to be responsible for the lax panicles and rolled leaves. Panicle density is acomplex character, which consists of many component characters such as spike-let number, panicle length, and numberof branches (Futsuhara et al 1979). Panicle laxness in this mutant could be attributed to the decrease in total spikelets and branches, especially secondary branches (see table).