Abstract: Branch traits are the most important part of ornamental quality on cut chrysanthemum. Heterosis and genetic analysis of branch traits such as primary branch number，branch height will provide a very important guidance for cut chrysanthemum breeding program. In this study，genetic analysis was carried out for four branch traits of cut chrysanthemum based on phenotypic data collected in 2011—2012 from 92 plants of a F1 population derived from the crossing between cut chrysanthemum‘QX-145’（female parent）and‘Nannong Yinshan’（male parent），which have different branching characteristics by applying single generation segregation analysis method of major gene plus polygene mixed genetic model. The result indicated that the 4 branch traits were widely segregated in F1 population with coefficient of variation（CV）ranging from 14.60% to 38.89%. The phenomena of heterosis and extra-parent segregation existed generally in F1 pogeny. Compared with mid-parent value（MPV），the heterosis value of mid-parent （H_m）of the 4 investigated branch traits，except primary branch length，showed a significant difference degree at 0.01 level，and the ratio of heterosis value of mid-parents（RH_m）for the three traits were–21.46%，–46.96%，and – 8.85%，respectively. According to the correlation analyze of branch traits from F1 population，4 pairs of traits were extremely significant correlations among 6 pairs. The mixed genetic analysis suggested that primary branch length and branch angle were fitted to A-0 model and no major gene was detected. The primary branch number and branch height are accorded with A-4 model with a negative complete dominant effect with major gene heritability of 51.45% and 53.92%.

Key words: cut chrysanthemum, branch trait, heterosis, major gene plus polygene, genetic analysis