Abstract
To elucidate the cross-compatibility among 9 species of genus Fagopyrum, the pollen tube growth in intra- and interspecific pollination was investigated. 120 pollination treatments were conductcd under screen house conditions in their fully flowering stage. Florets were harvested 4 hours after pollination, and pollen tubes were viewed on a fluorescent microscope. Measurements of pollen tube length were made on the longest pollen tube per style and 6-30 styles were observed per pollination treatment. The pollen tubes of F. esculentum and F. cymosum grew similarly in their reciprocal pollination, and the pollen tubes of thrum in crosses among F. Ieptopodum. F. capillatum, F. pleioramosum. F. urophyllum and F. callianthum showed satisfactory growth. Besides, the pollen tubes of F. tataricum in the style of F. esculentum and F. cymosum grew satisfactory as well as the self pollination of F. tataricum, in contrast, the pollen tubes of F. gracilipes were inhibited in the styles of F. esculentum and F. cymosum. When F. tataricum was used as a female parent, the pollen tube in all of the 8 interspecific crosses could penetrate into the micropyle. It is clear that there was a close re-lationship between the PL : SL ratio and the frequency of pollen tube reaching the ovary. Accordingly, it is suggested that the combinations showing high pollen tube growth in this interspecific crosses have a high potential of interspecific cross-compatibility. By cluster analysis based on the similarity of pollen tube growth, the species of Fagopyrum can be classified into two groups.
