Inheritance of Semidwarfism in Rice, ORYZA SATIVA L

The inheritance of plant height was investigated in a ten-parent diallel cross of diverse rice cultivars. Parents included two tall japonica lines and eight semidwarf lines. Data from parent, F(1), F(2 ), and F(3) generations indicated that the majority of height variation among the ten parents could be accounted for by three major genes with additive loci effects. D51, 72/2234-11, and G33 (derived from the known major-gene indica semidwarf Dee-geo-woo-gen) all were found to possess an allelic, partially recessive semidwarfing gene (sd(1)). Additional semidwarfing genes were detected in D66 (sd(2), fully recessive) and in CI 9858 (sd(3), partially to fully recessive). Relative magnitudes of additive effects were sd(1) > sd(2) >/= sd(3). Hokuriki 76, Tedoriwase, and IV 29-4 were found to be dwarfed by a multiple-gene system. Hayman-Jinks diallel cross analysis on parent and F(1) information (1974 and 1975) and on parent and F(2) information demonstrated the presence of significant additive and dominance variation, but epistasis was not detected. A preponderance of dominant alleles with partial dominance for increased plant height was observed. Since diallel statistics reflect properties of genes with larger effects, the genetic model proposed from segregation analysis was in substantial agreement with predictions of the Hayman-Jinks analysis.