Survey of Japanese medicinal plants for the detection of allelopathic properties.

Abstract

Plants with allelopathic properties were screened among Japanese medicinal plants using the lettuce seed germination and seedling growth tests and Fusarium oxysporum germination and hyphal growth tests. spore Plants with allelopathic properties were more fre- quently selected among these medicinal plants than among common crops and weeds. The strongest activity which was observed in Pulsatilla cernua (okina-gusa) and Crematis paniculata paniculata (sen-nin-sou), both Ranunculaceae, followed by Inula helenium (oo-guruma), Thymus vulgaris (French thyme), Ammi visnaga, Laurus nobilis (laurel) was manifes- ted by both plant growth inhibition and fun- gicidal properties. Water extracts of Allium tuberosum and Allium sativa and methanol extracts of Glycyrrhizae glabra and Curcuma longa displayed a strong anti-fungal activity, but did not affect plant growth. On the other hand, Phytolacca americana, Cinnamomum sieboldii, and Mentha piperita exhibied a strong plant seed germination and seedling growth inhibition, but had no effect on fungi.