Correlations between Floral Characters and the Days to Heading in Rice (Oryza sativa L.)

Abstract

The mean values of anther length, stigma length and the number of pollen grains per spikelet were significantly lower in Japanese cultivars than in Indica and Javanica varieties. Days from transplanting to heading and the mean temperature during 30 days before head-ing were positively and significantly correlated with the anther length and the number of pollen grains per spikelet which were highly correlated each other, but were not correlated with the stigma length and spikelet length. The spikelet length, however, was positively and significantly correlated with the stigma length, anther length and the number of pollen grains per spikelet. Genetically improved parental strains to raise hybrid rice varieties of Japoleica type adaptable for cool area wlll be developed by introduc{ng efficient genes for floral characteristics from Indica and/or Javanica varieties into Japanese cultivars.