INTERSPECIFIC CROSS-COMPATIBILITY IN FAGOPYRUM ACCORDING TO POLLEN-TUBE GROWTH

To elucidate the cross-compatibility among 9 species of genus Fagopyru m, the pollen tube growth in intra- and interspecific pollination was investigated. 120 pollination treatments were conducted under screen h ouse conditions in their fully flowering stage. Florets were harvested 4 hours after pollination, and pollen tubes were viewed on a fluoresc ent microscope. Measurements of pollen tube length were made on the lo ngest pollen tube per style and 6-30 styles were observed per pollinat ion treatment. The pollen tubes of F. esculentum and F. cymosum grew s imilarly in their reciprocal pollination, and the pollen tubes of thru m in crosses among F. leptopodum, F. capillatum, F. pleioramosum, F. u rophyllum and F. callianthum showed satisfactory growth. Besides, the pollen tubes of F. tataricum in the style of F. esculentum and F. cymo sum 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 clos e relationship between the PL : SL ratio and the frequency of pollen t ube reaching the ovary. Accordingly, it is suggested that the combinat ions showing high pollen tube growth in this interspecific crosses hav e a high potential of interspecific cross-compatibility. By cluster an alysis based on the similarity of pollen tube growth, the species of F agopyrum can be classified into two groups.