Analysis of Percentage of Productive Tiller in Rice by the Genetic Model “Major Gene Plus Polygene”

A joint five generations (P₁, P₂, F₁, F₂ and F_2∶3) derived from a cross of HFA 1 (indica) ×02428 (japonica), two parents exhibited multi-tiller and less tillers respectively, were evaluated to estimate the genetic model and genetic parameters of percentage of productive tiller (PPT) using the mode of major gene and polygene mixed inheritance of quantitative traits. The results showed that the PPT in rice was controlled by the mixed genetic model of one-major-gene plus polygenes (model D-4). The heritability of PPT of major gene in F₂ and F_2∶3 generation varied from 55.51% to 53.57% and those of polygenes varied from 33.13% to 38.94% respectively, which suggested that the breeding for high PPT rice should not only take into consideration both major genes and polygenes, but also carry out the selection for it at the early stage of breeding procedure. The additive effect and the dominant effect of PPT in the joint generations were -19.92 and -6.48 respectively, which implied that the negative interaction effects of polygenes should be considered in high PPT breeding.