Abstract
The Sandwich Method enables us to assay the allelopathic activity of the leaf litter of a donor plant inserted in agar medium, and evaluate the effects on the growth of the receptor plant. The allelopathic activity was determined as the percentage of growth of the radicle length of the receptor plant, lettuce (Lactuca sativa), grown in the agar medium containing the test plant leaf with that in the control medium containing agar only after 3 days at 20°C. We collected 29 plant species on 2nd February and 46 plant species on 28th June at the Yamashina Botanical Research Institute in Kyoto. Oxalis corniculate, Elaeocarpus zollingeri, Nageia nagi, Mucuna sempervirence, Atoropa belladonna, Moringa oleifera, Cinnamomum cassia, Pimenta dioica and Illicum anisatum showed very strong allelopathic activity; growth of radical length was suppressed to 8-30 ％ of that of the control. The plant species were medicinal plants, poisonous plants or oxalic-rich plants. Elucidation of the allelochemical is needed to make the allelopathy information useful to agriculture.
