Abstract
1.This investigation was conducted to clarify the mode of inheritance of cool tolerance in rice, form the view point of its breeding. 2.In this study, the F1∼F4 generations from an inter-variety cross ‘Somewake 'X' Aomori No.5' were used. ‘Somewake' is a local variety of high cool tolerance and panicle weight type with color glume and long awn, and ‘Aomori No. 5' is a crossbreeding variety of low cool tolerance and panicle number type without glume color and awn. 3.The degree of cool tolerance was evaluated by sterility of the materials tested in a field irrigated with cool water (14°C). 4.Variance of cool tolerance based on transformed data: Angle=sin-1√(sterility (%)), was partitioned into D, H and E components according to MATHER's method. Based on these estimates, heritability and the number of effective factors were estimated. 5.Consequently, cool tolerance was supposed to be nearly completely dominant and determined by apolygene system(probably more than 7 effective factors) with an additive dffect. 6.Heritability for cool tolerance was comparatively high even in early generations and a fairly good agreement was obtained with those estimated by other various methods. 7. Linkage relations between one of the effective factors for cool tolerance and the Rp gene which localozed the glume color and between the other one of them and the An gene (one of two awn genes) were recognized respectively.
