ABSTRACT
A specific method for assessing allelopathy was developed using intact plants growing in an agar medium without nutrients. There are several routes of action of allelopathy and this method deals with transferring allelochemicals through root exudates. A heat-resistant, transparent plant-box apparatus was developed to contain non-sterile plant tissue culture because of its ability to withstand autoclaving and easy observation of the root zone. The candidate donor plant was grown in sand for one to two mon to adapt it for the agar medium; then transplanted into a root zone-separating tube positioned inside the plant-box. A special low-temperature gelatinizing agar that solidifies at 30–31°C was used in order to avoid heat shock. An acceptor plant (lettuce) was seeded on the surface of the agar and incubated under certain conditions for 5 d. Allelopathic activity was calculated from the first regression curves between the radicle and hypocotyl length and the distance from the root zone. Using this method, a total of 336 plant species belonging to 48 families were evaluated. Among these plants, velvetbean (Mucuna pruriens) and oat species (Avena sp.) were found to have the strongest inhibitory activity.
