Identification And Prediction Of Heterosis On Autumn Cabbage Breeding Materials

In this experiment,the tested materials are 7 autumn cabbage inbred lines and compunding 12 combinations according to the incompleted diallel cross design.The test materials were tested in the field,and the results of the survey were analyzed for heterosis and combining ability;Using morphological markers and In Del molecular markers on the genetic distance analysis of 7 autumn cabbage parents.To explore the relationship between parental genetic distanceand and heterosis?combining ability.Following are the results :(1)Agronomic traits cluster analysis divided 19 materials into two groups.The I group was divided into two subgroups,the first subclass contained three parents,R2?R3 and R4,the second subclass contained S1 and S2.The II group contains R1 and S3.Principal component analysis screens out five higher-scoring combinations: R2×S1?R2×S2?R4×S2?R2×S3 and R4×S3.(2)The genetic distance of In Del markers in parental inbred line is from 0 to 0.8462,average distance is 0.4556.The clustering analysis was carried out by UPGMA,the autumn cabbage materials were divided into four groups based on 0.63 genetic similarity.The first group includes two parents,S1 and S3,the second group includes R2,the fourth group includes R1?R3?R4 and S2,where R3 and S2 have almost no genetic differences.(3)Analysis of variance and heterosis: Analysis of the variance showed that the differences between the combinations reached significant or extremely significant levels,and there were heritable differences among the traits.The heterosis of each trait has a large variation,and heterosis was widespread;the higher advantage of the hybrid combinations: R2×S1 ? R3×S1 ?R4×S2?R2×S3 and R3×S3.(4)Relationship between parental genetic distance and heterosis: The linear correlation between genetic distance and heterosis index is not significant.Through the two-dimensional coordinate scatter plot analysis of the five major traits of F1 generation,it was found that the heterosis index of plant height had no obvious relationship with the In Del genetic distance;when the In Del genetic distance was less than 0.3846,the outer leaf number and head weight heterosis index is related to the In Del genetic distance,the correlation coefficients are 0.999 and 0.888,respectively;the heterosis index of the head compactness and core cross-sectional area showed different growth and decrease patterns in different In Del genetic distance intervals.The heterosis index of plant height,head weight and head compactness showed different patterns of increase and decrease in the quantitative traits genetic distance range of different;when the quantitative traits genetic distance was in the range of 5.116 ~ 5.957,the number of outer leaf,core cross-sectional area heterosis index is related to the quantitative trait genetic distance,the correlation coefficients are 0.998 and-0.999,respectively.Using quantitative traits genetic distance and the In Del molecular marker genetic distance can predict the heterosis of yield of the combination of small genetic distance between parents.(5)Relationship between parental genetic distance and combining ability: The linear correlation between genetic distance and general combining ability,special combining ability and total combining ability was not significant.Only the special combining ability of plant breadth and width of outer leaf and In Del genetic distance reached significant level,and the correlation coefficients were-0.641 and-0.580,respectively.Through the two-dimensional coordinate scatter plot analysis of the five major traits of F1 generation,it was found that when the In Del genetic distance is less than 0.3846,the total combining ability effect of plant height is related to the In Del genetic distance,the correlation coefficient is 0.883;there is no obvious change in the total combining ability effect of the outer leaf number;the total combining ability effect of head weight,head compactness and core cross-sectional area showed different increase and decrease patterns in different In Del genetic distance intervals.When the quantitative traits genetic distance was in the range of 3.859~4.187?3.681~3.993 and 4.187~5.957,the corresponding total combining ability of plant height,number of outer leaves and core cross-sectional area were correlated,and the correlation coefficient was 0.951?0.985 and 0.978,respectively;the total combining ability effect of head weight has no obvious change law;the total combining ability effect of head compactness generally shows an upward trend.Using the In Del molecular marker genetic distance can predict the total combining ability effect of yield of the smaller genetic differences between parents.(6)Comprehensive analysis results: excellent parent materials have R2?R3 and S1.Significant combinations of heterosis(F1)have R2×S1 and R4×S2.