Study on the Characteristics of Florescence and Pollen in Lagerstroemia speciosa

大花紫薇开花及花粉特性研究

[ Objective] To study the characteristics of florescence and pollen in Lagerstroemia speciosa. [ Method ] The process of flower opening and pollen tube germination of Lagerstroemia speciosa was observed and the pollen viability was determined through in vitro germination. [ Result] Sepals of L. speciosa started to diverge at 4：30 am, at 7： 00 am petals flatten up, anther diverged, and the stigma secreted a large number of mucus, it was the best time for artificial pollination. Boric acid and sucrose had a great effect on in vitro pollen germination of L. speciosa, the combination which made highest rate of pollen germination, was sucrose 150 g/L ＋ boric acid 20 mg/L ＋ CaCI2 10 mg/L. Through the fluorescence microscope, it was known that four hours after flowering, a lot of pollen grains germinated on the stigma, six hours after flowering, lots of pollen tubes entered the style and reached to 1/4 length of the style, 12 hours after flowering, pollen tubes concentrated into a beam forward, and reached to 1/2 length of the style, 24 hours after flowering, lots of pollen tubes entered the ovary in a beam and then fertilized and produced seeds. [ Conclusion] The results provide some basis for utilizing L. speciosa to breed.

1材料与方法1．1大花紫薇开花习性观测试验地为广西壮族自治区柳州市城站路的街道绿地，该绿地位于市区南面，属亚热带季风气候，年平均气温20．5℃，极端最高气温37．2℃，极端最低气温-3．8℃，最冷月1月平均气温10．4℃；年平均降水量1500．1mm，其中80％以上的降水集中在4～10月，年平均蒸发量160614mm，年平均相对湿度79％；全年无霜期319d，霜期46d（霜日约8d），寒潮期间常有0～-1℃的低温天气，寒害时有发生。土壤为砂岩发育成的红壤，较肥沃，pH值为5．5～6．0。