| Rice seedling blight is one of the main diseases of rice in China,Fusarium oxysporum is one of the most important pathogens.Rice seedling blight is a serious threat to rice production in China,which can cause serious economic losses to rice production.Therefore,it is very important to control rice seedling blight with high efficiency and environmental protection.Biological control has become a hot topic in the world in recent years because of its green and environmental characteristics.Among them,seed immune technology is to use biological control bacteria to coat the seeds of crops.By stimulating the immune response of plants,seed immune technology can be used to prevent and control plant diseases.This method is simple and efficient,and has become one of the main contents of biological control.In this paper,rice seeds were coated with biocontrol fermentation liquid.Through large-scale screening,indoor screening and pot experiment,the bacterial strains which can induce rice to produce systemic resistance to rice seedling blight were obtained.At the same time,the taxonomic status of the biocontrol bacteria with inducing and resisting effects was identified,and the bacteriostatic effect of biocontrol bacteria on Fusarium oxysporum and a variety of pathogenic fungi was confirmed through confrontation test.The results are as follows:1.Screening of induced resistant strains to rice seedling blight: 1761 strains of bacterial strains preserved in this study were coated with the seeds of Liaojing 212,inoculated with Fusarium oxysporum for preliminary screening,and 60 strains with induced resistance were obtained.The fermentation broth of 60 strains with the inducting effect was recoated with the same rice seed.In the middle of July,inoculation of Fusarium oxysporum was carried out by bacteria and soil method,and the incidence was investigated 15 days later.According to the investigation on the incidence,disease index and control effect of rice seedling blight,the control effect of 8 biological control bacteria was better after screening.The results showed that Sneb859,Sneb26,Sneb131 and Sneb1677 could promote the growth of rice.Sneb859 had the best effect on the germination rate,root length and bud length of rice seeds.The germination rate of Sneb859 was 8.30% higher than that of the control.At 13 days,the bud length was 1.50,1.15 and 1.13 times as long as the control,and the root length was 1.17,1.23 and 1.18 times as long as the control.The strains Sneb926,Sneb1017 and Sneb1623 promoted the bud length and root length in the early stage of rice,and inhibited them in thelater stage.Sneb129 promoted the early bud growth of rice,but not the later,and promoted the root growth.The results showed that Sneb859,Sneb131 and Sneb26 had lower incidence,lower disease index and better performance.The results showed that Sneb859 had the lowest disease index and the best control effect on rice seedling blight.The control effect was56.14%,which had a significant promoting effect on the growth of rice seedlings.2.Identification of resistant strains of rice to rice seedling blight induced by seed coating:using morphological and physiological biochemical characteristics identification method,combined with 16 S r DNA molecular biology analysis method,the 8 strains of effective biocontrol bacteria obtained from preliminary screening were classified and identified,and the classification status of biocontrol bacteria was clarified.The results showed that Sneb859 was Bacillus cereus,Sneb26 was Bacillus aryabhattai,Sneb131 and Sneb926 were Enterobacter ludwigii,Sneb129 was Bacillus subtilis,Sneb1017 was Pseudomonas marginal Strain Sneb1623 is Bacillus amyloliquefaciens and Sneb1677 is Bacillus velezensis.3.The bacteriostatic and antagonistic test of Sneb859,the strain with the best resistance activity to Fusarium oxysporum: the bacteriostatic effect of the fermentation liquid of Sneb859,a biocontrol strain,on a variety of plant pathogens was studied by means of plate confrontation method.The results showed that the fermentation liquid of Sneb859 had no bacteriostatic effect on Fusarium oxysporum and Fusarium equisetum,but had bacteriostatic effect on Fusarium graminearum,Fusarium solanacearum and Rhizoctonia solanacearum But the effect is not significant.The results showed that through systematic screening and identification,the fermentation liquid of Bacillus cereus Sneb859 coated the seeds of rice Liaojing 212,and the plate culture confrontation test showed that the fermentation liquid of Sneb859 had no bacteriostatic effect on Fusarium oxysporum,the pathogen of rice seedling blight.It is speculated that rice seeds coated with Sneb859 can induce resistance to Fusarium oxysporum,the pathogen of rice seedling blight. |
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