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

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.通过测定种子萌芽期生物学指标和盆栽苗期生理指标,研究谷子不同部位(叶片、茎秆)不同浓度(原液、10倍稀释液、50倍稀释液、100倍稀释液)浸提液对反枝苋、藜、狗尾草3种谷田恶性杂草的化感作用。结果表明: 谷子叶片、茎秆水浸提液对3种杂草均存在显著化感作用,且不同浓度浸提液化感作用存在差异,总体表现为原液有抑制作用,稀释液(10、50、100倍)有促进作用。叶片、茎秆浸提液原液处理下,反枝苋、藜、狗尾草的发芽率分别下降了63.9%、37.3%和41.7%,根长仅为对照的27.8%、37.8%和18.4%,芽长仅为对照的34.5%、27.7%和17.6%,净光合速率为对照的66.6%、89.9%和88.2%,蒸腾速率为对照的69.0%、87.5%和56.1%,原液对3种杂草的综合化感效应指数为-0.699、-0.716和-0.795,表现出较强的化感抑制作用。稀释液处理下化感促进作用随稀释倍数增加呈先上升后下降趋势,其中50倍稀释液促进作用最强,3种杂草的发芽率、根长和芽长均与对照达到差异显著水平,综合化感效应指数分别为0.261、0.217和0.165。谷田伴生杂草大量生长与谷子秸秆中化感物质淋溶有关。.