A Study Of Allelopathic Effect Of Water Extracts From Abutilon Theophrasti Medic. On Lactuca Sativa L., Portulaca Oleraca L. And Amaranthus Retroflexus L.

Velvetleaf (Abutilon theophrasti medic) is an annual plant in the family Malvaceae. Allelopathy of the aqueous extract from different parts of abutilon in different growth periods on the seed germination and seedling growth of Lactuca sativa L., Portulaca oleraca L. and Amaranthus retroflexus L. was investigated and the allelochemicals of aqueous extract from leaf were preliminarily identified in this study, hoping to find effective materials which can prevent and control the weeds, to reduce the environmental pollution caused by chemical pesticides, and to increase the biosecurity.The results are as follows:(1) The inhibitory effects of abutilon in different growth periods on the seed germination and seedling growth of Lactuca sativa 1., Portulaca oleraca 1. and Amaranthus retroflexus 1. are different. The allelopathy of abutilon in mature stage is higher than that in seedling period. The allelopathy of different parts of abutilon is also different. The allelopathy of aqueous extract of root is stronger than that of stem, leaf, and seed under the same concentration.(2) The responses of different testing plants to allelopathy of abutilon are also different. The response of Amaranthus retroflexus 1. to the allelopathy of abutilon is the most sensitive, that is the seed growing of Amaranthus retroflexus 1. be inhibited totally under the highest concentration of aqueous extract from leaf.The response of Lactuca sativa 1. to abutilon is less sensitive, and response of Portulaca oleraca 1. is the weakest.(3)It is different for the response sensitivity from different parts of testing plants on the allelopathy of abutilon aqueous extract. The inhibitory effect of allelopathy of abutilon aqueous extract on the root growth of three plants is the strongest. The inhibition rate increased with the increasing concentration and difference between various concentrations was significant. The inhibitory effect of abutilon aqueous extract on the shoot growth showed that low concentration promoted growth and high concentration inhibited growth. The level of response to allelopathy of seed germination is between the responses of root and shoot.(4) HPLC-MS method was used to determine the composition of aqueous extract from abutilon leaf and one material which owns the strong allelopathy was identified. Its mass charge ratio(m/z) is 610, and its retention time is almost the same with rutin, as well as the three pieces of ion fragments. So the main allelochemicals of abutilon is rutin after integrated all the information.(5)In the bioassay of Amaranthus retroflexus 1., the inhibitory effect can be increased with rutin added into the aqueous extract of abutilon leaf, but single rutin’s inhibitory effect was not significant. These results showed that rutin is the main allelochemicals of allelopathy.