Allelopathic effects of water extracts from different parts of foxtail millet straw on three kinds of weeds

Abstract

We examined the allelopathic effect of extracts from different parts of foxtail millet straw with different concentrations (undiluted water extracts, 10-fold, 50-fold, and 100-fold dilution) on three different kinds of malignant weeds (Amaranthus retroflexus, Chenopodium album, and Setaria viridis) by water extract. In this experiment, we measured biological indicators for seed germination period and potted seedling physiological parameters. The results showed that water extract of foxtail millet leaves and stems had significant allelopathic effects on the three species of weeds, with the effects of different concentrations being different. Undiluted water extract inhibited the growth, while dilution (10-fold, 50-fold, 100-fold dilution) promoted the growth. Under the treatment of undiluted water extract of leaf and stem, the germination rate of three weeds decreased 63.9%, 37.3% and 41.7%, respectively, while root length was only 27.8%, 37.8% and 18.4% of the control. The bud length was only 34.5%, 27.7% and 17.6% of the control. The net photosynthetic rate accounted for 66.6%, 89.9% and 88.2% of the control. The transpiration rate accounted for 69.0%, 87.5% and 56.1% of the control, while the synthesis allelopathic index of the three weeds were -0.699, -0.716 and -0.795 by undiluted water extract, respectively. Results implied strong allelopathic inhibition. The allelopathy promoting effect of dilution increased first and then decreased with the increases of dilution folds. Among which, 50-fold dilution had the strongest promoting effect with the germination rate, root length and bud length of the three weeds being significantly different from those of the control, with the synthesis allelopathic index being 0.261, 0.217, and 0.165, respectively. A large number of associated weeds grow in foxtail millet field which is related to the leaching of allelopathic substances in straw.