Studies On Allelopathic Inhibition Of Aromatic Plants On Weeds

In the past several decades scholars have paid much attention to biocontrol on weeds via plant allelopathy. Aromatic plants are well known to have the ability of allelopathy and are expected to be used in biocontrol on field weeds.In order to screen inhibiting effects of aromatic plants, aqueous extracts of overground part of nine aromatic plants(Mentha piperita L., Origanum vulgare L., Nepeta citriodora L., Nepeta cataria L., Thymus marschallianus Willd., Salvia officinalis L., Ocimum basilicum L., Achillea millefolium L. and Ruta graveolens L.) were used as donors andthreeweeds as acceptors.to simulate aromatic allelopathy viarain leaching in the natural condition. Firstly, biological detection were conducted in petri dishes to sequence weed suppression of nine aromatic plants, then matrix pot experiment was carried out to verify the effect of weed suppression and to evaluate impact on wheat growth.Secondly, LC-MS was used in component detection special for target extracts which have outstanding weed inhibition. Finally, inhibitory intensity of allelochemicals components and their interaction were studied.Our petridish assays showed that Aqueous extract of Ocimum basilicum L., Ruta graveolens L. and Nepeta cataria L. present stronger inhibiting effects on Chenopodium album L., and aqueous extract of Ocimum basilicum L., Nepeta citriodora L., Ruta graveolens L. and Mentha piperita L. have higher inhibiting effects on Amaranthus retroflexus L., and Ocimum basilicum L. and Ruta graveolens L. have inhibiting effects on Portulaca oleracea L. Meanwhile, we found that the strongest inhibiting effects happened at 5% concentration for all of water extracts. Besides, three weeds have different sensitivity to different aromatic plants indicating that aromatic plants have selective inhibition on weeds. Furthermore, roots of the weeds are more sensitive to the water extracts than seedlings.Bonsai experiment showed that the 5% aqueous extracts of Ocimum basilicum L. and Ruta graveolens L. presented effective inhibiting on Chenopodium album L., and promote the wheat growing.We found five allelochemicals from extract of Ocimum basilicum L. and three allelochemicals from Ruta graveolens L. and three allelochemicals from Nepeta cataria L. in the presence of 70.47μmol/L, 54.40μmol/L and 50.88μmol/L respectively.Then, we performed the suppression effect test of single and mixed composition for five allelochemicals at the known concentration detected in the aqueous extracts of Ocimum basilicum L. Through comparing inhibition rate of root length,evaluating inhibitory effect of allelopathic substances, Through comparing statistical contribution value of different allelochemicals to root length inhibition rate, evaluation of the interactions between the allelopathy components. The results showed that the inhibition rate is exist diference of thirty-one components, a mixture of vanillin and salicylic acid composition is the largest inhibition rate. In addition, through the SPSS factorial analysis results show that the interaction effect between allelopathy components, mixed component relative to the single-component effect performance for gain or antagonism or both gain and antagonism.