Abstract
The objective of this investigation was to clearly the changes in the allelopathic effects of water extracts of soil amended with powdered plant materials (shoots of Artemisia princeps, Miscanthus sinensis, Pueraria lobata, Glycine max and Zea mays, and leaves of Acacia morisima and Solidago altissima) on the germination and root elongation of lettuce.
1. The germination and radicle elongation of lettuce were inhibited by the extracts of soil amended with any of these plant materials in the early period of incubation, although the inhibitory effects disappeared with the duration of the incubation period (Fig. 2, Fig. 3). Besides, radicle elongation was even promoted after the disappearance of the inhibitory effect (Fig. 2, Fig. 3).
2. The allelopathic effects of the extract of soil amended with leaves of S. altissima on the germination and radicle elongation of lettuce were strongest and persisted throughout the incubation period in this experiment (Fig. 2, Fig. 3).
3. Changes in the allelopathic effects of the extracts of soil amended with the ethanol soluble fraction of black wattle and tall golden rod leaves were comparable to those of the extract of soil amended with the unfractionated leaves (Fig. 4).
