Comparison Study of Flowering Process in Three Dichogamous Lauraceae Species

Abstract:

In order to understand the characteristics of breeding system of dichogamous Lauraceae plants, the flowering dynamics of hermaphrodite of Cinnamomum burmannii, Phoebe sheareri and P. chekiangensis were compared. The phases of floral phenology and insect pollinators were observed. Stigma and pollen viability, nectar volume, nectar sugar concentration and natural pollen deposition were measured. Fruit setting were checked with different methods. The results showed that the start time and duration of female and male functional stages were different among three species. Apis cerana was the main pollinator at both of female and male functional stages. The nectary in the 4^th round staminodia at female functional stage secreted nectar, while that in the 3^rd round of filament base secreted nectar in male functional stage. Nectar volume and nectar sugar concentration had no significant difference at different flowering stages. Stigma receptivity and pollen viability were higher in both male and female functional stages, there was natural pollen deposition during the whole flowering stages. Fruit setting of three species was in the order of outcrossing and pollination>natural pollination>bagging, indicating that there were certain pollination restrictions. Therefore, it was suggested that the difference of time distribution between male and female stages in Lauraceae might be related to the secretion rhythm of nectary in staminodia and the third round stamen.

Key words:Cinnamomum burmannii;Phoebe sheareri;P. chekiangensis;Dichogamy;Flowering;Nectary;Staminode