ABSTRACT
The allelopathic effect of aqueous extract of lupin [Lupinus terms cv. Giza 1] seeds at 5 percent, 15 percent and 25 percent concentration [w/v] on soybean after 30 days of seedling establishment could be effective in enhancing the production. The data illustrated that soybean seed yield was stimulated by lupin extract at 5 percent concentration, no appreciable changes with 15 percent level whereas the highest concentration [25 percent] showed an inhibitory effect .The promotion or reduction of soybean yield, caused by lupin extract treatments was paralleled with increased or decreased total protein and oil constituent of the seeds. The biochemical interference of lupin extract may afford greater possibilities for mechanism of allelopathic action that depends upon physiological response, capacity of soybean. This is reflected mostly on the primary and secondary metabolic products. So the 5 percent lupin extract has a positive allelopathic effect due to its ability to increase plant growth and to stimulate soybean yield production. This finding suggests that the potential beneficial involvement of lupin seed aqueous extract as crop-crop stimulator, by its application at lower concentrations after soybean emergence, should be effective in enhancing crop production