Study On Prediction Of Phenotypic Values And Heterosis Of Agronomic And Quality Characters In Rapeseed (Brassica Napus L.)

In this study,in order to study the prediction method of phenotypic values and heterosis of agronomic,quality traits,5 cytoplasmic male sterile lines(maintainer lines corresponding) and 33 restorer lines of different origins,were used to produce 165 hybrids by North Carolinaâ…¡(NCâ…¡)mating design.Analysis of the correlation and line regression for agronomic and quality characters was made between combining abilities and heterosis.Two methods of cluster analysis based on phenotypic characters and storage protein markers were compared to study the relationship between genetic diversity of 38 parental lines and F1 performance.The results are indicated as follows:1.Results from heterosis analysis of agronomic traits in rapeseed showed that Significant heterosis for agronomic and quality traits was tested in rapeseed.Heterosis of quality was less than that of agronomic.Heterosis for 3 components of yield per plant was in the sequence:total number of siliques per plant＞seeds/silique＞1000-seed weight,while the PRO,C18:1,FAT was in the sequence:FAT＞C18:1＞PRO.2.Results showed that the traits such as the yield per plant and total number of siliques per plant,indicate the heredity over high parent,seeds/silique was near high parent,1000-seed weight showed the heredity near low parent,while the quality traits such as GLU,C16:0,C18:2,C18:3 indicate the heredity near low parent,but FAT,C18:1,C20:1 indicate the heredity near high parent,PRO and C18:0 indicate the heredity under low parent.3.The result from yield per plant and its 3 components analysis in rapeseed showed that total number of siliques per plant and number of siliques on branches was the same most important,seeds/siliques,number of first branches and number of second branches was the same more important.In order to obtain high yield kind,more total number of siliques per plant and higher seed yield/plant was the best match.4.Parental effects on agronomic and quality traits of hybrid were different by different traits.For first branches and seed yield/plant,female male parent effects were less than male parent.For seeds/silique and 1000-seed weight,male parent effects were less than male parent,but for total number of siliques per plant,the effects of parent is the same.For the same quality trait,the effects of female parent were generally less than that of male parent.Parental effects on the performance of hybrid also depended on the types and the values of combining abilities.The higher combining abilities parents had,the greater effects on offspring they made.5.By the sum of two parents' GCAs was the most powerful to predict the phenotypic values of F1 agronomic(R²:0.550-0.798)and F₂ quality performance(R²:0.555-0.945)by combining abilities in rapeseed,and the later is more accurate.6.Results from correlation analysis indicated that the high-parent heterosis of agronomic traits was generally predicted by the phenotypic values and SCA in rapeseed,while the heterosis of quality traits was generally predicted by the phenotypic values and by the sum of two parents' GCAs or by SCA in rapeseed,but by the sum of two parents' GCAs was more helpful.The heterosis prediction of F₂ quality by the sum of two parents' GCAs was more accurate than the heterosis prediction of F₁ agronomic by SCA and the prediction of the phenotypic values of F_1sagronomic and F_2squality by combining abilities was more accurate than the prediction of heterosis.7.The phenotypic cluster could distinguish significant differences parent materials of different ecologic region.To cluster the parent material precisely,the method of cluster analysis based on glutelin marker and albumins marker was not the helpful.8.Results correlation analysis indicated that genetic distances(GD_glutelin)based on glutelin marker significant positively related to yield per plant(r=0.215^**),but the determination coefficient was low(R²=0.046),while GD_glutelinand GD_albyminswere negative related(r=-0.183^*)and significant negatively related(r=-0.209^**)with seed oil content, GD_glutelinand GD_albyminsshowed a weak relation with mid-parent heterosis significant positively related to protein content(0.250^**,0.232^**).GD_glutelinwere significant positively related with mid-heterosis of protein content(r=0.220^**),significant negative related with mid-parent heterosis of,seed oil content(r=-0.216^**),GD_albyminshowed a weak relation with the mid-parent heterosis of seed oil content and protein content.To predict phenotypic values of seed yield per plant and quality heterosis of seed oil content and protent content,The analysis showed that the method of prediction by the sum of two parents' GCAs was more powerful than by GD_glutelin.The genetic distance based on phenotypic could not be used to predict the heterosis of agronomic and qulity traits except the phenotypic value of C18:3 and the mid-parents of yield per plant and C18:3.