Submitted to: International Journal of Allelopathy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 1996
Publication Date: N/A
Interpretive Summary: The common weed, corn spurry, was noted to cause severe growth reduction in some crops. The purpose of this investigation was to demonstrate that allelopathy (the production of substances by one plant that inhibits the growth of other plants) contributes to the competitiveness of this species. Natural corn spurry populations greatly reduced the growth of English pea and collard plants in the field. In the greenhouse, corn spurry plants an ground corn spurry tissue reduced broccoli and pea growth, and in the laboratory, extracts of corn spurry tissues were inhibitory to both crops. These results provide evidence that production of phytotoxic substances by corn spurry which inhibit the growth of neighboring plants is an important factor in the severe impact that this weed has on some crops.
Technical Abstract: In a field study, interference by an indigenous population of corn spurry reduced the shoot weights of English pea and collard by 93 and 72 percent, respectively. In a greenhouse experiment where physical light competition by corn spurry was prevented, broccoli shoot weights were reduced by corn spurry, but pea weights were not different from the controls. Corn spurry shoot homogenates incorporated into a greenhouse potting medium reduced th growth of both species, and a concentration effect was observed. Corn spurry shoot and root tissues were sequentially extracted with hexane, ethyl acetate, methanol, and 50% aqueous methanol, and the extracts were tested for inhibitory activity using millet seed germination and broccoli seedling growth bioassays. Methanol and aqueous methanol extracts were inhibitory to broccoli; whereas, all extracts inhibited millet germination. Although both shoot and root extracts were inhibitory, shoots appeared to have a higher concentration of inhibitors than roots.