Floral morphology and hybrid fruiting characteristics of distylous Primula forbesii

摘要

Primula forbesii Franchet is a biennial wild herbaceous, endemic to China. We first examined the morphology of pollen and stigma of thrum and pin flower using SEM line image analysis system, then observed the pollen germination and growth in thrum andpin stylus. The fruit set of hybrid combinations was investigated. The pollen of P. forbesii belonged to 3-syncolpraporate pollen. Pin and thrum flower had different pollen size and the pollen in thrum flower was longer than that in pin flower. Pin flower had long stylus and papilla cells. The papilla cells of pin flower were 1.5 times longer than that in thrum. There was a significant difference about the pollen growth in stylus between self-pollination and cross-pollination. After pollinating 72 h, pollen tube had extended into the ovary in cross-pollination. In self-pollination, most of the pollen tube in the middle part of the stylus stopped growing, only a few of pollen tube extended into the ovary. Ultimate swelling appeared in stylus after self-pollination. The hybrid combination (P(9)xT(c)) had the highest seed set up to 64.58%. There were significant differences with the other combinations. The fruit set of thrum flower self-pollination was 3.33%. No fruit was harvested from pin flower self-pollination. This study provided fundamental discoveries for further research toward the primrose breeding.