| In 2016,when investigating the incidence of tobacco planting in Luoyang tobacco area and Luohe tobacco area in Henan Province,it was found that the tobacco-borne diseases mainly consisted of black shank and root-knot nematodes,and some areas also had root black rot,angular spot disease,etc.In order to reduce the occurrence of tobacco soil-borne diseases and improve the yield and quality of tobacco leaves,through the control measures on the affected tobacco fields in Yiyang County,Ruyang County,Luoyang City,Henan Province,and Linyi County,Luohe City,Henan Province,such as the application of biological fertilizer,lime nitrogen,intercropping,crop rotation,etc.,to study the changes of soil microbial quantity and structure and their effects on pathogenesis.The rhizosphere soil was taken before transplanting,rosette stage,vigorous growth stage and mature stage.The number of culturable microorganisms,basic physical and chemical properties of soil,high-throughput gene sequencing were detected.The agronomic traits of tobacco plants,the morbidity at maturity stage,the yield quality and economic traits of flue-cured tobacco in the test fields of Bio-bacterial fertilizer and lime nitrogen were determined.The number of microorganisms,flora structure,dominant strains and their changing characteristics in tobacco rhizosphere soil under different control measures were analyzed and determined to provide theoretical basis for effective prevention and control of soil-borne diseases and improvement of tobacco production quality.The results are as follows:(1)The application of biological bacteria fertilizer is beneficial to the colonization and mass reproduction of beneficial microorganisms in the soil,which has a significant and stable impact on soil microbial structure and soil-borne disease control.Sphingomonas was the most effective bacterial genus in the soil of Bacillus amyloliquefaciens B1619.The mature treatment period T was 15.53% higher than that of the control C.Gibberella was used as a fungal genus to promote plant growth.The long-term treatment T was higher than the control C 1058.60.%.The measures improved the micro-ecological balance of rhizosphere soil of tobacco plants,and had a great impact on the community structure and quantity of rhizosphere soil microbes.The yield and output value increased by 4.94% and 3.50%,respectively.(2)From before transplanting to rosette stage,the amount of culturable bacteria,fungi and actinomycetes in the rhizosphere soil of limestone(treated T)was reduced by 87.0%,89.8% and 87.3%,respectively,but gradually recovered with the growth of tobacco plants;normal fertilization(control C)The number of fungi removed from the field decreased by 82.1% in the stalk period,and the difference in the number of bacteria and actinomycetes was not significant.In the middle and late growth stages of tobacco plants,the microbial content of T was generally lower than that of control C.High-throughput sequencing results showed that the application of lime nitrogen had an effect on the microbial population and community structure of rhizosphere soil of tobacco plants,and the effect on fungi was more obvious.The incidence of root knot nematode disease in T tobacco plants was half of that of control C;the incidence of black shank was significantly lower than that of control C,and the control efficiency of root knot nematode and black shank was 50.0% and 41.8%,respectively.The yield per mu increased by 4.65%,and the output value per mu increased by 7.19%.(3)Using different crops for teasing: the number of cultivable bacteria and actinomycetes in the rhizosphere soil of continuous cropping field increased with the growth of tobacco plants,and the number of fungi decreased;the number of bacteria cultured in the rhizosphere soil using sweet potatoes and peanuts With the increase of sweet potato growth,the number of fungi and actinomycetes decreased.The cultivating bacteria and fungi content in the rhizosphere soil of wheat field with wheat tiller increased with the growth of wheat,and the number of actinomycetes decreased.From before transplanting of tobacco plants to the vigorous growth stage,At the genus level,the total content of fungi content in the rhizosphere soil of continuous cropping fields decreased from 72.35% to 17.29%,from 51.68% to 39.84%,and from peanuts mites increased from 51.68% to 79.39.At the phylum level,the fungal content of the rhizosphere soil in the continuous cropping field decreased from 89.42% to 30.92%,the fungus content of the sweet potato was reduced from 74.28% to 55.06%,and the fungus content of the peanut mites increased from 74.28% to 96.24.%.In the wheat field and its control tobacco field,the bacterial content of continuous cropping tobacco field was between 94% and 96% in two periods;the fungal content in the control tobacco field was between 90% and 95%,and the fungus content in wheat field was between 95% and 98%.The number of Gibberella in the rhizosphere soil taken by sweet potato was significantly lower than that before transplanting;the number of Gibberella in the rhizosphere soil taking peanuts was significantly increased;the wheat pollination could increase the content of soil probiotic Sphingomonas,while the rhizosphere The content of soil fungus Schizosaccharomyces was significantly reduced.It can be seen that through the regulation of sweet potatoes,peanuts and wheat,the number and types of fungi in the rhizosphere soil can be significantly changed,and the content of probiotics in the rhizosphere soil can be improved,and the effect of wheat stubble adjustment on rhizosphere soil microorganisms was the best.(4)The sweet potato-tobacco intercropping can enrich the alkaline nitrogen,available phosphorus and available potassium in the rhizosphere soil of tobacco in the middle and late growth stages.The number of culturable bacteria in rhizosphere soil of monoculture and intercropping tobacco fields decreased with the growth of tobacco plants.Actinomycetes first decreased and then increased with the growth of tobacco plants,and then decreased slightly at mature stage.Fungi first increased and then decreased with the growth of tobacco plants,the single crop tobacco field reached the highest in vigorous growth stage,and the intercropped tobacco field reached the highest in rosette stage.At the level of fungi,six dominant bacteria appeared in the single crop field,and ten dominant bacteria appeared in the intercropped tobacco field,indicating that the intercropping was conducive to the increase of the dominant species,and the floristic structure of the rhizosphere soil microbes changed.The soil micro-ecological structure tends to be benign.The benign development of soil micro-ecology in the rhizosphere of tobacco plants is conducive to the normal growth of tobacco,improve resistance,and has certain effects on the prevention and control of tobacco soil-borne diseases.(5)The promotion experiment found that the application of biological fertilizer and lime nitrogen can increase the proportion of the superior tobacco leaves,the yield and output value of the flue-cured tobacco.The bio-fertilizer test field that was continuously applied for two years was increased by 1.00% and 4.2%,respectively,in terms of the ratio of superior tobacco and tobacco production value compared with the one year of the bio-fertilizer test field.Considering the economic cost and application effect,it is recommended to promote the demonstration and preferably adopt the treatment of applying lime nitrogen. |
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