On Breeding System and Pollinating Characteristics of Sinocaycanthus chinensis,an Endangered Plant in Dalei Mountain

Sinocalycanthus chinensis displays showy flowers. Its pistil development and anther growth,belonging to protogyny,differed slightly. These floral syndromes were showed to favor outcrossing. However,the anthers dehisced at the third day after flower opening,suggesting that the species may occur in delayed selfing. In order to test this hypothesis,the pollination biology of two S. chinensis populations with different altitude in Dalei Mountain was studied. The main results were as follows: The stigma receptivity of S. chinensis was the highest at the second day after flower opening. And it began to decline at the anther dehisced,but it was not significantly diminished. The seed set rate of S. chinensis under bagged without emasculation was 42.01% and 44.44%,and was significantly lower than that of the control,which was 53.82% and 52.43%. The seed set rate under emasculation without bagged was 21.53% and 13.89% respectively. It was significantly lower than that of the control,and was also significantly lower than that of under bagged without emasculation. The selfing rates were 61.3% and 73.6%,suggesting that the reproduction of this species mainly depended on self-pollination.The reproductive assurances were only 78.1% and 84.8%. This result was mainly caused by the pollen limitation,and the mild inbreeding depression at early fruiting phase.