Studies On Eveluation Of Standard Cut Flower Of Chrysanthemum Branching Characteristics And Heredity Analysis

As one of the four cut flowers in the world,chrysanthemum is the main cut flowers for production and export.In China,the standard cut flower of chrysanthemum with single flower is the main type of export now.It requires several times of artificial erasing lateral branches and buds in the production of standard cut flowers of chrysanthemum,which is time-consuming,high labor costs and easy to cause the main bud damage.Therefore,developing the cultivation with less lateral branches and buds is the fundamental way to solve the problem.In this study,28 standard cut flower of chrysanthemum cultivars was studied to establish the classification system on branching characteristics of standard cut flower of chrysanthemum,divided into five grades by grey correlation value.New varieties of improved branching characteristic were selected in a segregating F1 population derived from a cross between standard cut flower of chrysanthemum through the system.At the same time,the inheritance of branching characteristics was investigated in the segregating F1 population to lay the theoretical foundation on standard cut flower of chrysanthemum breeding.The main results of this study are as follows:1.The 28 varieties of standard cut flower of chrysanthemum had been chosen as materials.The synthetic system was established by the means of AHP and grey correlation analysis,selecting 10 character indexes of three aspects of branch traits,which were lateral branches,lateral buds and winter suckers.By analysing the weight of each evaluation index values,the ratio of lateral branch to internode number after second bud picking(0.2143),lateral bud number(0.1667)and the ratio of lateral branch to internode number after first bud picking(0.1429)were the most important indexs to the branch traits.Main to lateral bud diameter ratio and the distance between main and lateral bud showed less importance.The lest important indexs were the lateral branch length after first bud picking,the lateral branch length after second bud picking,winter suckers number,winter suckers ratio and winter suckers length.According to the weighted grey correlation value,all the 28 varieties standard cut flower of chrysanthemum had been divided into five grades.There were six varieties in the two of the first grades show less lateral branches and buds,which can be used as the breeding materials of less branch of standard cut flower of chrysanthemum.2.A segregating F1 population derived from a cross between standard cut flower of chrysanthemum 'Yuka' and 'Jinba' was evaluated by the branching characteristic system which was established by the means of AHP and grey correlation analysis.According to the weighted grey correlation value,all the 95 strains had been divided into five grades.The six strains in the first grades show less lateral branches and buds,can be used as the breeding materials of less branch of standard cut flower of chrysanthemum.The sixteen strains in the second grades can be the alternative materials.3.The inheritance of six lateral branch and bud traits,i.e.lateral branch length and number,ratio of lateral branch to internode number,main to lateral bud diameter ratio,lateral bud number,and distance between main and lateral bud were investigated in a segregating F1 population derived from a cross between standard cut flower of chrysanthemum 'Ynka' and 'Jinba' with different lateral branch and bud characters using the major gene plus polygene mixed inheritance model.The results showed that,the six lateral branch and bud traits widely segregated and extra-parent segregants existed generally in F1 population with the coefficients of variation ranging from 23.78%to 50.65%.All the six traits showed significant heterosis at a P<0.01 level,and the ratio of heterosis value of mid-parents for the six traits were 19.13%?-53.74%?-42.31%?8.54%?-16.90%and 31.28%,respectively.Results from the mixed genetic analysis revealed that two pairs of major genes were detected for all investigated traits excluding distance between main and lateral bud.The lateral branch length,ratio of lateral branch to internode number,main to lateral bud diameter ratio and lateral bud number fit into B-1 model,compatible with the presence of two pairs of major genes displaying additivity-dominance-epistasis.Lateral branch number accorded with B-2 model,controlled by two pairs of major genes with an additive-dominant effect.The heritabilities of major genes for the five traits were 77.07%,74.38%,96.72%,64.38%,and 53.07%respectively.