Investigation On Branching Traits And Optimal Planting Density Of Spray Cut-Chrysanthemum

Chrysanthemum(Chrysanthemum morifolium Ramat.)is a perennial herb of the Compositae.It has diverse flower colors,various flower types,and long vase life.Branching is one of the important factors affecting the morphology of chrysanthemum plants.The shoot branching traits such as the number of branches,branch angle,and branch length are closely related to the ornamental quality and economic value of cut chrysanthemum.Besides,different cultivation modes will also affect the branching of cut chrysanthemum.At present,the same planting density is often used for different varieties of spray cut-chrysanthemum,ignoring the different branching ability of different spray cut-chrysanthemum,which is easy to cause the waste of germplasm resources.Therefore,it is of great significance to investigate and analyze the shoot branching traits of spray cut-chrysanthemum and explore the influence of different planting density on the shoot branching traits of spray cut-chrysanthemum for the rational utilization of variety resources.This experiment used two-year data to analyze the influence of planting years on the related traits of spray cut-chrysanthemum shoot branching.With the help of GWAS,the relevant allelic variants of the side shoot branching traits of spray cut-chrysanthemum were mined.The branching ability of spray cut-chrysanthemum varieties resources was evaluated,and the best planting density of different varieties of spray cut-chrysanthemum was explored.The stability and related loci of the shoot branching traits of spray cut-chrysanthemum have been clarified preliminarily,the branching ability evaluation system of spray cut-chrysanthemum has been established,and different spray cut-chrysanthemum varieties suitable for high-density and low-density planting have been selected.The main findings are as follows:1.Observed and measured 9 shoot branching related traits of plant height,number of leaf nodes,total number of lateral buds,number of upper lateral branch,number of lateral flower buds,stem diameter,primary branch diameter,primary branch angle and primary branch length of a natural population composed of 195 spray cut-chrysanthemum species for two consecutive years.The results showed that plant height,total number of lateral buds,upper lateral branch number,stem diameter,primary branch diameter,primary branch length under the two years were significantly different,and number of leaf nodes,number of lateral flower buds,and primary branch angle were stable.With the help of GWAS,28overlapping SNPs were found and 6 candidate branch-related genes were determined.2.For 204 spray cut-chrysanthemum varieties,one measurement and analysis of 11shoot branching related traits of plant height,branch initiation height,number of leaf nodes,total number of lateral buds,number of upper primary branches,number of lateral flower buds,number of upper secondary branches,stem diameter,primary branch diameter,primary branch angle and primary branch length with the aid of principal component analysis and membership function method,the branching ability of spray cut-chrysanthemum is evaluated.The branching ability of 204 spray cut-chrysanthemum varieties is divided into 5 grades from weak to strong,and each grade includes 43,77,53,20,11 spray cut-chrysanthemum varieties in turn.‘Nannong Zimei’,‘Nannong Yuxuan’,‘Nannong Taoliu’were the spray cut-chrysanthemum varieties with strong branching ability and‘Baipenghua’,‘Nannong Xiaohongmao’,‘Nannong Bingqilin’were the spray cut-chrysanthemum varieties with weak branching ability.3.The variation degree of 16 shoot branching related traits of 16 spray cut-chrysanthemum varieties under three planting densities of 178/m~2,100/m~2,and 64/m~2were explored and compared.The results showed that the planting density had a greater influence on the traits of spray cut-chrysanthemum plant height,branch initiation height,stem diameter,number of upper secondary branches,crown width,and number of flowers.It had little effect on primary branch angle and total number of lateral buds of spray cut-chrysanthemum The‘Nannong Caidiandian’,‘Nannong Xiangchengdian’,‘Nannong Jidian’,‘Minihuang’,‘Nannong Bingjie’,‘Nannong Bingqing’,‘Nannong Lixue’,‘Nannong Bingxue’and‘Nannong Wujin’spray cut-chrysanthemum varieties are suitable for high-density cultivation,while the‘Nannong Hongdiandian’,‘Nannong Hongyun’,‘Nannong Daixue’and‘Nannong Songmang’spray cut-chrysanthemum varieties can try low-density cultivation.In summary,by investigating and analyzing the branching traits of different spray cut-chrysanthemum varieties,the test results laid a theoretical foundation for the subsequent mining of branching-related genes.It is conducive to the rational utilization of germplasm resources of spray cut-chrysanthemum and provides a scientific reference for guiding agricultural production.