Effect of Various Aqueous Plant Extracts upon Seed Germination

Aqueous extracts of residues from 23 plant species inhibited the germination of clover, lettuce, radish, and wheat seeds. Extracts from potato, sugarbeet, sagebrush, green soybean, alfalfa, pea, and bean were extremely toxic to germinating seeds, while the extracts from Douglas-fir, peat moss, and sphagnum moss stimulated the growth of some germinating seeds. The degree of toxicity was dependent upon the maturity of the plant residue, the concentration of the extract, the species from which the extract was obtained, and the species of seed used in making the bioassays.