Genetic analysis of transparency and chalkiness area at different filling stages of rice (Oryza sativa L.)

Seven cytoplasmic male sterile lines and five restorer lines of indica rice (Oryza sativa L.) were used to analyze genetic effects on transparency and chalkiness a-rea at four filling stages. A developmental genetic model for quantitative traits of triploid endosperm in cereal crops were used for the data analysis. The unconditional analysis showed that the accumulated genetic effects of genes expressed from the initial time (at flowering and fertilization) to the filling time t were all significant for transparency and chalkiness area. These results indicated that the genetic effects of the triploid endosperm, cytoplasmic and diploid maternal plant were all of importance for both traits at various filling stages, especially for maternal additive and dominance effects on transparency. The relatively high endosperm and maternal additive effects on transparency and chalkiness area indicated that the two traits could be improved by selection in early generations. From the conditional analysis for the net genetic effects of genes expressed during time t - 1 to time t, new expression of genes in endosperm, cytoplasm and maternal plant for transparency and chalkiness area was found at most of the filling stages. especially from 8 to 14 days after flowering for transparency and from 1 to 14 days after flowering for chalkiness area. Predicted genetic effects and conditional genetic effects at different filling stages showed that transparency and chalkiness area of offspring could be improved by using some parents, such as Zuo 5, because of their better endosperm additive and cytoplasmic effects. (C) 2002 Elsevier Science B.V. All rights reserved.