| In order to save production cost,it is common to cultivate strawberries year after year in greenhouse facilities in some places,and accordingly serious strawberry stubble disease has also occurred.In order to find out the species and biological characteristics of the pathogen of strawberry root rot and provide scientific basis for biological control of strawberry root rot,the sampling and analysis were carried out in a typical strawberry planting shed in Linyi City,Shandong Province.The research methods are as follows:using the pathogen of strawberry root rot as the target pathogen,using the biological control method to screen the antagonistic bacteria,identifying the antagonistic bacteria and studying the biological characteristics,applying the antagonistic bacteria to the pot experiment and field experiment,and preliminarily evaluating the resistance and growth promoting effect of antagonistic bacteria.The main results are as follows:1)A large number of diseased strawberry plants were collected in the infected strawberry shed,and the strain ZH-G01 was obtained by tissue isolation method.After purification,the strain ZH-G01 was identified by morphological characteristics and r DNA its sequence analysis.The results showed that the positive side of the plate colony of strain ZH-G01 was white velvet,no pigment was produced,the back was slightly yellow,the conidia were divided into 4 cells,5 cells,spindle like,3 brown in the center The its sequence of strain ZH-G01 is more than 99% similar to Neopaetalotopsis clavispora in Gen Bank.The pathogen was identified as Neopaetalotopsis clavispora by combining morphological and molecular biological characteristics.Gen Bank accession number is MN559410.The results showed that PDA medium was the most suitable medium,spore medium could produce spores rapidly and in large quantity,the most suitable growth temperature was 25 ℃,the most suitable p H value was 4.0-10.0,light had no significant effect on the growth of mycelium,the most suitable carbon source was soluble starch,the worst effect on the utilization of xylitol,the most suitable nitrogen source was yeast extract,the most effective on the utilization of urea Poor.2)Taking ZH-G01 as the target pathogen,in order to obtain better antagonistic bacteria,72 antagonistic bacteria were screened and rescreened by the method of flat plate confrontation,and three strains with good biocontrol effect were screened out.The microscopical observation of 10×4 times and 10×10 times of the edge mycelia of bacteriostatic circle showed that the edge mycelium of bacteriostatic circle was thin,twisted,increased branches and other abnormal phenomena.According to the morphological,physiological and biochemical characteristics and molecular biology,three antagonistic strains were identified as Bacillus amyloliquefaciens-17,Bacillus velezensis-27 and Bacillus subtilis-Y1-7.The optimum culture conditions were as follows: temperature 32 ℃,liquid volume 50ml(250ml triangle flask),initial p H6-7,carbon source glucose,nitrogen source yeast powder,initial p H6-7,initial p H6-7,temperature 30 ℃,liquid volume 50ml(250ml triangle flask),initial p H6-7,carbon source glucose,nitrogen source yeast powder For soluble starch,the nitrogen source is yeast powder;for antagonistic strain y1-7,it is not sensitive to bacitracin and ampicillin.The optimal culture conditions are: temperature 30 ℃,liquid volume 25ml(250ml triangle flask),initial p H6-7,carbon source is glucose,and nitrogen source is yeast powder.3)The results showed that the three antagonistic strains had different inhibition on Fusarium solanum,Botrytiscinerea Pers.,Botryosphaeria berengriana f.sp.Piricola,Pseudoperonospora cubensis,F.oxysporum and F.graminearum.The three antagonistic strains had phosphorus releasing effect,and produced IAA and iron carrier.The crude extract of antagonistic strains had antagonistic target The results showed that all the three biocontrol strains had the potential of promoting growth and disease resistance.4)Pot experiment showed that the control effect of bacteria in the same life was better than that of disease resistance,the control effect of compound bacteria was better than that of single strain,and the control effect was as high as 73.68%.The field experiment showed that the control effect of compound bacteria treatment was 57.18%-66.00% and 12.97%-37.99% higher than that of single bacteria treatment,the plant height of compound bacteria treatment increased by 17.84%-26.04%,the number of leaves per plant increased by 40.28%-56.86%,the area of leaves increased by7.51%-31.00%,and the number of flowering and fruiting increased by 57.18%-66.00%and 12.97%-37.99% respectively At the same time,the content of soluble sugar and vitamin C increased by 17.99%-19.69%,the content of vitamin C increased by 23%,the content of total acid decreased by 16.33%-37.79%,and there was no effect on anthocyanin content. |
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