| Six varieties (lines) with great difference in quality characters were used as parents to make complete diallel crossing(6 X 6) in accordance with the Griffing method 1 in order to study the genetics of quality characters in Beifang Japonica Rice by using a full genetic model and statistical method for quantitative characters of seeds in cereal crops(Zhu & Weir). Quantitative traits of Japonica Rice analyzed were brown rice rate (BRR), milled rice rate (MRR), ratio of length to width (L/W), degree of chalkiness(DC), amylose content(AC), gel consistency(GC), crude protein content(PC), Which were measured from each sample of parents and F2s. The main results were as follows:The varieties (lines) with superior quality characters were used as female parents in quality breeding of rice because the progenies of 93-9 and ND7 used as female parents basically maintained most of superior quality characters of female parents, which showed that general characteristics of quality characters were controlled by the additive genetic effect of triploid endosperm, also indicated that some quality characters probably were controlled by maternal or cytoplasm genetic system. By comparing parents with F2s, it was indicted that the average of most quality characters in hybrid F2s was between two parents, but over parents, and obvious differences exited among combinations.The results of genetic variance components showed seven quality characters were all controlled by the genes of diploid embryo, triploid endosperm, cytoplasm and diploid maternal plant. The sequence of BRR and PC influenced by four genetic systems were genetic effect of endosperm > genetic effect of embryo > genetic effect of maternal > genetic effect of cytoplasm; the sequence of HRR, L/W, DC and ACmwere genetic effect of endosperm > genetic effect of maternal > genetic effect of embryo > genetic effect of cytoplasm; the sequence of GC were genetic effect of endosperm > genetic effect of embryo > genetic effect of cytoplasm > genetic effect of maternal. In addition, quality characters were obviously influenced by additive interaction effects, for example, the CAo.Ae of GC and PC, the CAe.Am of BRR, L/W, DC and AC, the CDo.Dm of HRR were all significant at the 0.01, 0.05 or 0.10 levels, which indicated that another genetic system probably has less role in this quality character if some system were utilized to improve some quality character.Quality characters of rice all had very significant endosperm heritability and selection response, significant cytoplasm heritability and selection response (except PC), but BRR, L/W and AC had negative significant maternal heritability and selection response, which indicted that it was better to improve HRR, GC and AC by using method of single-seed selection with single-plant selection, to improve BRR and L/W by using single-seed selection in early generation, and to improve AC by using single-plant selection, namely attaching importance to maternal plant selection.This experiment adopted the method of AUP (Adjust Unbiased Prediction) to estimate the value of genetic effects for parents, which revealed that in rice breeding with different quality as importance, Pi(ND8) and P4(ND7) probably were used as parents to improve BRR, P4(ND7) and P6(TX103) probably were used as female parents to improve HRR, P3(93-9), P4(ND7) and P5(T20) probably were used as parents to improve L/W, Pa(M58), P3(93-9) and P4(ND7) probably were used as parents to improve DC, P4(ND7) probably was used as parent to improve AC, P?(93-9) probably was used as female parent to improve AC and GC, P5(T20) and P6(TX103) probably were used as parents to improve GC, P2(M58) and P6(TX103) probably were used as parents to improve PC, and P5(T20) probably were used as female parent to improve PC.It was revealed that the average of mean heterosis were all not high, six qualityrvcharacters were between -0.1005(GC) and 0.0347(AC) except that DC was 1.1086, which probably resulted from the segregation of genotype, so that heterosis were lo... |
PDF Full Text Request