BREEDING SYSTEM AND POLLINATION BIOLOGY OF PAEONIA DELAVAYI (PEAONIACEAE), AN ENDANGERED PLANT IN THE SOUTHWEST OF CHINA

摘要

Breeding system and pollination biology of Paeonia delavayi (Peaoniaceae) from Shangri-La, Yunnan Province, southwest ofChina were studied. Flowering phenologies and flower visitors were observed or collected from 2008 to 2011. The pollenviability, stigma receptivity and pollination efficiency of different visitors were detected and tested. The florescence lasted for 6-9d in a single flower from mid-May to late June. A high percentage of flower damage promoted early anther dehiscence.Flowers started disseminating pollen at 1-2 d after flowering, and lasted for 5-6 d. Pollen viability could be preserved for morethan 10 d at normal temperature. High seed rate from the stigma was observed at 1 d before flowering to 3d after flowering, andthe dissemination hysteresis was defined as protogyny. The P/O ratios were 6,124 to 9,713:1, suggesting that the larger quantityof pollen to increased the seed setting rate. Three species of bees, eight species of beetles, seven species of syrphid flies, fourspecies of ants, and three species of butterflies were observed on the flowers. P. delavayi rewarded to the visitors by releasingfragrance, providing pollen and nectar. On the bodies of the visitors under stereomicroscope and scanning electron microscope(SEM), much pollen from the plants of similar flowering period inner community were found which indicated that theseincompatible visitors were not species-specific pollinators. The bagging experiments showed that P. delavayi was selfincompatibleand no apomixes. Anemophily only played a minor role in the fertilization. A few seeds with poor plumpness canbe produced by geitonogamy. Seed setting rate of artificial xenogamy was higher than natural pollination. Artificial control ofthe visitors’ species showed bees being the most important pollinators. Beetles and ants participated in pollination to someextent and were unstable. Syrphid flies and butterflies were very unreliable with low pollination efficiency. Reproductivesuccess depended largely on cross-pollination assisted by pollinator activities, especially the bees.