| Weeds can interfere with the yield and the quality of crops,and are a major problem in all crops growing area.Currently,using chemical herbicides are among the main control measures used for weeds and are parts of weed management;however,with the continuous use of a large number of chemical herbicides,it can lead to the human health problems and the emergence of weed resistance.There is still a need for an environmentally friendly,economical and effective method for weed management.Samples of soil were collected from the farmers’ wheat fields during 2020 August in Huangzhong District,and the plate seed germination test was used to isolate a strain that had the inhibitory effect the weeds seed germination.The morphological characteristics,molecular identification,inhibitory activity analysis and preliminary separation of active components of the strain were carried out,providing more biological resources for weed management.The main research results are as follows:(1)A total of 15 strains of actinomycetes were obtained from soil by dilution isolation method,and the numbers codes were 15-5,15-6,3-17,14-6,12-16,AGG1,G7-1,G1-1,3-20,12-1,15-7,5-16,13-4,6-4,and 3-19,respectively.The plate seed germination test initially obtained 4 strains that had inhibitory effect on seed germination,of which strain 15-5 had the best inhibitory effect on seeds,and the inhibitory rate of its fermentation broth on radicle and shoot of Avena fatua seeds was83.4% and 89.98%;the radicle and shoot inhibition rates of Brassica juncea seeds were 43.30% and 78.39%,respectively.The results of the crop safety test showed that it had no effect on the germination of Vicia faba,Pisum sativum,Triticum aestivum and Hordeum vulgare seeds.Therefore,the further research on strain 15-5 was carried out.(2)Through 16 S r RNA gene sequence and phylogenetic tree analysis,strain 15-5was established on the same evolutionary branch with the closest strain Streptomyces lavendulae(99%),and combined with the analysis of morphological and cultural characteristics,the strain 15-5 was identified as the Streptomyces lavendulae.(3)Strain 15-5 was subjected to large-scale liquid fermentation,and the fermentation broth was centrifuged and filtered,extracted three times with equal volumes of ethyl acetate and n-butanol,and evaporated and concentrated under a rotary evaporator to obtain a crude extract.A.fatua,B.juncea and Bromus tectorum was used as targets,the results of the plate seed germination test showed that the activity of the crude extract of ethyl acetate phase was the best,and the inhibition rates of radicle and shoot on the growth of the three weed seeds were almost 100%.(4)After centrifuging and concentrating the fermentation broth of strain 15-5,15 fractions were obtained by separation by silica gel column chromatography and thin layer chromatography,which were recorded as Fr.1～Fr.15.The radicle and shoot inhibition rates of A.fatua,B.juncea and B.tectorum were all as high as 90%.Fr.5was analyzed by HPLC.Under the condition of methanol: water=45:55,the inhibitory component 1 and component 2 were obtained,and the inhibitory effect of component1 was stronger,and its retention time was 16.894 min. |
