Germplasm Innovation and Establishment of Comprehensive Evaluation System for Hedgerow Garden Chrysanthemum

Abstract

Garden chrysanthemums are a group of chrysanthemums (Chrysanthemum morifolium) that are mostly used in garden landscape collocations. Because most garden chrysanthemum varieties have low plants and poor space effects, they have certain limitations in garden landscape applications. In this study, we selected seven garden chrysanthemum varieties with excellent characteristics for artificial hybridization and intercross parentage to obtain new varieties with good traits we need. The phenotypic characteristics of the F1 offspring in terms of plant height, crown width, crown height ratio, number of main branches, branching intensity, plant form, inflorescence diameter, number of flowers per plant, number of ray florets, flower color, and days from planting period to coloring period were analyzed and systematically evaluated. Subsequently, a comprehensive evaluation system was established using the analytic hierarchy process (AHP) and k-means clustering method. We built a comprehensive analysis model, calculated the weighting of each evaluation factor, and multiplied the weight value by the score of the evaluation index standard of each factor to obtain the comprehensive score of each plant. All F1 plants were divided into four grades: excellent grade accounting for 13%, good grade accounting for 28%, medium grade accounting for 36%, and poor grade accounting for 23%. Then, we analyzed the differences of some quantitative traits between Group E (hybrids in excellent grade) and Group O (hybrids in good, medium, and poor grades). There were significant differences in plant height, crown height ratio, and the number of main branches but no significant difference in crown width. Combining with comprehensive score showed that Group E performed well overall. Finally, we selected five hybrid offspring with the highest overall scores in Group E as excellent variety materials of garden chrysanthemum for hedgerow. They were CH22, YQ73, HY08, CQ80, and HY07, respectively. We also found that plant height, lodging resistance, crown height ratio, plant form, crown width, and the number of main branches could be the main indicators in the AHP, which can be effectively applied to the comprehensive evaluation and breeding of garden chrysanthemums for hedgerows.