Analysis On Morphological Diversity And Pre-core Collection Construction In Cut Chrysanthemum

Chrysanthemum(Chrysanthemum morifolium)has formed a rich genetic variation in a long cultivation history,cut chrysanthemum especially,which has the most varies of colors and floral shapes.Collection and conservation of germplasm are the basis of breeding which means the key to accelerate the breeding process is to choose germplasm wisely.Material was collected in "China Chrysanthemum Germplasm Conservation Center",Nanjing Agricultural University.In this study,we investigate the phenotypic diversity of each germplasm resource to explore the construction of pre-core collection.The investigation on 15 phenotypic characters of 462 cut chrysanthemum resources was discussed in this paper.15 phenotypic characters was investigated in the standard cut chrysanthemum,while 19 phenotypic characters was investigated in anemone type.From cut chrysanthemum,18 each in single type,double-petalled type and the windmill type,16 in other types.Results show that most cut chrysanthemum shape are anemone and single type,accounted for 70.1%of the total percentage of ligulate flowers base towards the predominantly horizontal,longitudinal profile horizontally,flat disc type are 73.2%,69.3%and 73.2%respectively.Pink color mostly,flowering in October 20 between November 10.Leaves are long and deeply cleft leaves,with more and deeper leaf margin serrate.Plant height,leaf width,leaf length of the highest genetic diversity index,2.073,2.058,2.044,respectively.Comparing to the entire collection,various characters of the spray cut chrysanthemum are most similar.A candidate core collection was established using the date above.The construction of 462 cut chrysanthemum germplasm resources for the primary core germplasm was build.According to the ornamental characteristics,cut chrysanthemum was divided into two subgroups by hierarchical grouping method,the standard cut chrysanthemum and the spray cut flowers,then sampled separately.Results show that standard cut chrysanthemum clustering by longest distance he maximum to retain the original the genetic diversity of germplasm resources with sampled ratio of 40%,while major quality traits phenotype reserves at ratio of 100%.S method was better for spray cut chrysanthemum with sampled ratio of 30%.Finally,the core collection including 142 cultivars with reserving phenotypes ratio of almost 100%was established.Gentic diversity index of it was similar to the entire collection.The degree of variation coefficient of quantitative character is over 90%,and average t test there was no significant difference,the average genetic diversity index was 1.523;The spray cut chrysanthemum was most represntative both to the square root method and the 30%sampling,the quality traits phenotypic reserve ratio can reach 100%,quantitative character can reach more than 90%expect ray floret number;Verified with average t test,the average genetic diversity index was 1.565.Ultimately 142 core germplasm was selected,various characters genetic diversity index coincidence rates of which were over 95%,phenotypic retention ratio of which was almost 100%.