Analysis Of Floral Traits,Flower Pigment Composition And Hybrid Breeding Experiments Of Different Color Cultivars Of Rhododendron

Rhododendron is a generic name for plants of the genus in the Rhododendron family,which is one of the ten most famous traditional flowers in China.At present,the research on Rhododendron is mainly focused on the investigation of germplasm resources of wild resources,domestication of introduced cultivars and propagation and cultivation,and there are few studies related to horticultural cultivars.In this study,we selected different color cultivars of Rhododendron as experimental materials,observed and counted the flower organ traits of different cultivars,and provided reference for the selection and breeding of new floral cultivars of Rhododendron through cluster analysis and ornamental evaluation analysis;secondly,flower color was taken as an important breeding target,and the flower color composition of different color cultivars of Rhododendron was studied to provide theoretical basis for Rhododendron color breeding.Finally,based on the results of floral organ tube trait investigation and flower color research,we can configure hybrid combinations with rich flower color as the breeding target and carry out hybridization experiments,which can breed a number of new variety resources and accumulate practical experience in selecting and breeding new cultivars of Rhododendrons.The main research results are as follows:1.phenotypic analysis and evaluation of Rhododendron traits: among 21 floral organ traits of93 Rhododendron cultivars,the quality traits flower color,petal type,flower type,sepals,flower spots,perianth segments and pistil traits were significantly different,and the quantitative traits flower diameter,corolla tube length and pistil length were rich in variation,with diversity indices of 4.46,4.52 and 4.51,and coefficients of variation of The diversity indices were 4.46,4.52 and 4.51,and the coefficients of variation were 21.98%,26.03% and 29.03%,respectively.The petalization was mainly in the sepals,pistils and stamens,and the degree of petalization was mild,moderate and severe in single or multiple parts.Petalization has a great influence on the floral structure of Rhododendron cultivars,while androgynophore petalization also affects Rhododendron offspring breeding.The 93 Rhododendron cultivars can be copolymerized into five major groups at Euclidean distance 15 using the indicators of flower color,petalization and flower type in cluster analysis,and the 93 Rhododendrons can be classified into four different ornamental classes according to two indicators of AHP weight value and gray correlation degree.2.Rhododendron pigment composition identification: Rhododendrons are rich in floral color,with a wide variation in floral phenotypes.L values are highest in white cultivars and yellow,followed by the pink family,and lowest in purple cultivars.a values are highest in red cultivars,followed by pink and purple,and lowest in yellow and white cultivars.b values are highest in red cultivars,followed by pink,white and yellow cultivars,and lowest in purple cultivars.In the separation and identification of color,trifluoroacetic acid extract was found to be effective in separation.A total of 21 compounds were obtained from the results of Rhododendron extract assay and composition analysis identification.They contained 8 anthocyanin glycosides and 9 flavonol compounds.The qualitative and quantitative analysis of anthocyanin s revealed that the anthocyanin components were mainly delphinidin and cornflowerin,and th e glycosidic binding types were 3-O-β-D xylopyranoside,5-O-β-D glucopyranoside,3,7-β-O di glucoside,3,5-diglucoside,3-O-glucoside,and 3-O-arabinose in five glycosidic binding forms.The composition and content varied among the different color groups,with the purple group being the most abundant in anthocyanin glycoside components,followed by the red,pink,and complex color groups,and no anthocyanin glycosides were detected in the white and yellow groups.The qualitative and quantitative analysis of flavonoid components found differences a mong cultivars,and individual variability in flavonoid components and contents in the same color group,with no significant differences among color groups.The highest contents of rhodo dendron 3-L rhamnoside,6-hydroxyl luciferoside-7-glucoside,gibberellin,and 8-hydroxyl lucife roside-8-O-arabinoside were presumed to be the major flavonoid components in Rhododendron.3.Different cultivars of Rhododendron flower color breeding experiments:In the Rhododendron cultivars,the maternal cultivars were selective and the results of the stigma fertility tests showed that all cultivars could be used as test material except for a few heavy cultivars.After cross-pollination of the six color rhododendrons,25 of the 55 cross combinations showed fruit expansion and three did not bear fruit at a later stage,and seeds from 22 cross combinations were harvested.The seeds of 22 hybrids were harvested,and the fruit set rate was higher for the purple,pink,red and compound color combinations as the parent,and lower for the white and yellow crosses as the parent,and lower for the crosses as the parent.The germination rate of 22 hybrids ranged from38% to 98%,with the highest germination rate of 92% for the red group and the lowest rate of 38% for the yellow group,with an average germination rate of 69.5%.The different germination rates were related to the affinity of the parents and the growth and development environment of the seeds themselves,not to the flower color.