Sexual Reproductive System Characterististics Of Physostegia Virginiana

Physostegia virginiana is one of Labiatae, belong to Physostegia. It is native to eastern North America and one of Chinese climatic type cold type plant. It is widely used in gardening landscaping. In order to provide the scientific bases for cultivation and crossbreeding, floral biology and breeding system were studied. Floral dynamic was observed in the field during the flowering period. Pollen viability and stigma receptivity were tested by MTT method. The number of pollens and ovules were estimated under the microscope. Result show that:1.Physostegia virginiana single flowers were lasts about 2-7 d. it is related to the environmental temperature, on the higher temperature condition,it is open fastly and fade faster;Air temperature is low,it is open slowly, fade also slow,and flowers can maintain a long time. Inflorescence can keep flowering 10～14 d days or so, it is flowering from beginning to the final about 64～75 d, it is early flowering faster, slower and the late flowering, it may be associated with temperature during flowering.The number of flowering and fruit setting several significant positive correlation between flower number, the more the more fruit number, seed setting rate is higher.2. Result show that:(1) it is high Flowering pollen viability at beginning of flowering. It is more than 70%. Pollen viability will become decline with time passed. It decreased less than 50% after 11 days and it died 17days later,so, pollen life 17d; (2) flowering day does not have to grant sexual stigma around the first 3-4d, stigma strongest, this when the pollen count pollen viability, home falls on the stigma and the germination rate on the stigma are the highest, to the first 7d stigma of losing can be granted;3. At the beginning of flowering of P. virginiana, the anther spreading, stigma is far away anther, stigma cann’t touch stigma and cannot undertake independent pollinate.After the anther spread, stigma is located in the central, thus, P. virginiana has the floral manipulations of dichogamy and herkogamy, P/O value and the OCI values indicate facultative xenogamy with the ability to self-pollinate spontaneously.4. Observed in the field and bagging experimental methods for leading fake flower breeding system were studied. Provide the basis for a false leader of crossbreeding. Different strains of the same species cross-pollination of seed setting rate and the highest rate, followed by higher natural conditions of cross-pollination and seed setting rate ratio, apomixis and seed setting rate was zero. P/O value and the OCI values indicate same breeding system.