Pollination Biology Research Of Four Primulina (Gesneriaceae) Species

Primulina (Gesneriaceae) has a demanding need of environmental factors, whose habitat is so unique that with the change of natural environment or human damage to the environment intentionally or unintentionally it will be broken, and then the species will be disappeared. This artical focuses on studying the breeding system and pollination biology of Primulina medica, P. eburnea, P. lijiangensis, P. cordata from the respects of flowering phenology, biological activities of pollen and stigma, the species and behavior of pollinators, P/O ratio, outcrossing index (OCI), bagging experiment. The purpose of the research is to make a sense of the flowering characteristic, pollination and breeding system of the four species, also it provides fundamental basis for in site conservation and ex-situ conservation, at the same time, we my find the reason why P. medica, P. lijiangensis, P. cordata are narrow distributed while compared with P. eburnea which is a widespread species.Primulina medica has a 4-5 days single flower cycle,5-20 inflorescences in one plant,7-60 flowers in one inflorescence, corolla white with pink,24 mm long in average, P/O ratio is 282.58 ±5.02, outcrossing index is 4, bagging experiment indicates that it is self-compatibility, low self-pollination rate in natural condition, need pollinators, effective pollinators are Anthophora florea and Trigona ventralis, Anthophora florea is the main pollinator, the reward of the pollinators is pollen, found no nectar.Primulina eburnea has a 6-8 days single flower cycle,1-10 inflorescences in one plant, 1-17 flowers in one inflorescence, corolla orchid,49 mm long in average, P/O ratio is 537±18.04, outcrossing index is 5, bagging experiment indicates that it is self-compatibility, low self-pollination rate in natural condition, need pollinators, effective pollinators are Anthophora florea and Bombus sp., the reward of the pollinators are pollen and nectar, average amout of nectar in sunshine day is 2.25±0.47 ?L, suger content is 51.91±1.49%, average amout of nectar in rainy day is 4.66±0.91 ?L, suger content is 34.82±1.10%.Primulina lijiangensis has a 3-5 days single flower cycle,3-12 inflorescences in one plant, 8-56 flowers in one inflorescence, corolla red,24 mm long in average, P/O ratio is 290.85±5.34, outcrossing index is 4, bagging experiment indicates that it is self-compatibility, low self-pollination rate in natural condition, need pollinators, effective pollinator is Trigona ventralis, the reward of the pollinators is pollen, found no nectar.Primulina cordata has a 6-8 days single flower cycle,1-6 inflorescences in one plant,1-3 flowers in one inflorescence, corolla orchid,55 mm long in average, P/O ratio is 331.76±13.08, outcrossing index is 5, bagging experiment indicates that it is self-compatibility, low self-pollination rate in natural condition, need pollinators, effective pollinator is Trigona ventralis, the reward of the pollinators are pollen and nectar, average amout of nectar in sunshine day is 1.03±0.21 ?L, suger content is 23.75±0.94%.Different floral syndrome of the four species is to attract more pollinators, completing the fertilization process, as a result getting a high maturing rate. Plants and pollinators cooperate coevolution under the long-term natural selection, for example:the outer wall of the pollen is reticulate, and there is so many mesh of uneven size and three germinal furrows in side, which make it easier to attach to the pollinators' back, whereas the pollinators'back has obvious hairs, making it capable of carrying more pollen. The behvior of the pollinators relate to the size of the pollinator and the flower. When the size of pollinator and flower fits, the pollinator lands on the abaxial lip, crawling into the corolla, when the recurved stigma come into contact with pollinator's back. Then the pollinator find the nectar crossing between the two filaments, at this time, the anther is broken, the pollen inside fall over the pollinator' back. When the pollinator visit the other flowers, the process of pollnation is completed. When the size of pollinator is smaller the the flower, they can't touch the stigma. But they can hold the anther when they collect pollen, at that time the pollen attach to the pollinator's abdomen and legs.Rainfall has a greatest effect on flowering pollination. It decreases the activity of the pollinator, dilutes the nectar, makes pollen inactivation, rots the corolla. Besides abiotic factors, the process of pollination is also affected by biotic factors. Stealler collecting nectar and injurious insects feeding on corolla will decrease the attraction to pollinators by flower.We can't find evidence to explain the reason why P. medica, P. lijiangensis, P. cordata are narrow distributed in the aspect of pollination biology.