2003 年 38 巻 p. 82-
Plants release any chemical compounds, allelopathic substances, affect the plant growth or fungal growth etc. It has been reported that germinating sunflower seeds had a species-selective allelopathic function, and an allelopathic substance, 4,15-dinor-3-hydroxy-1(5)-xanthene-12,8-olide (sundiversifolide), was isolated and identified from the exudates of germinating sunflower seeds. Sunflower has a strong allelopathy during seed germinating process. The strong allelopathy gradually reduce after the germination. The amount of the substance and allelopathic action were linear. We have also found that sundiversifolide inhibites some fungus growth. It has been found that the allelopathic substances from sunflower seeds show a strong inhibitory activity in dicotyledon rather than in monocotyledon. In this study, we investigated the effect of sundiversifolide on the oat coleoptile section test. In even monocotyledon, oat coleoptile, sundiversifolide weakly inhibited auxin-induced growth. Further investigations are under study. We have also purified and identified some substances, which may relate to allelopathic activity in sunflower seeds.