| Tobacco is an annual or limited perennial herb of Solanaceae,which has many functions.Throughout the growth period of tobacco,different microorganisms exist in the surrounding and rhizosphere soil,as well as in the tobacco plant tissues.Fujian is a big province of tobacco cultivation used paddy-upland rotation for a long time.In order to better understand the microbial community structure in the tobacco region of Fujian province,this study investigated from the following two aspects:(1)The effects of different organic fertilizers on tobacco fungal communityIn recent years,overuse of chemical fertilizers in tobacco plantation has caused many problems,e.g.,soil compaction.Partial replacement of chemical fertilizer with organic fertilizers is widely used in tobacco plantation.The rational use of organic fertilizers can also enhance the disease resistance of tobacco.However,there are many kinds of organic fertilizers available at present,therefore,it is very important to know the effects of different organic fertilizers on tobacco growth before choose the suitable organic fertilizers.Representative tobacco field with medium fertility in Nanping tobacco area in Fujian province was selected for experiments.From 2017 to 2019,different organic fertilizers(sesame meal fertilizer,rapeseed meal fertilizer,cow dung,chicken manure and straw)was used to replace partial chemical fertilizers,and pure chemical fertilizers as the control.During vigorous growth period,the treated tobacco plants,including roots,steams and leaves were collected.We analyzed the fungal community of tobacco plants by traditional isolation culture and high-throughput sequencing.The results showed that the dominant genera of leaf fungi treated with different organic fertilizers were Boeremia,Rhodotorula and Cladosporium.Replacing some fertilizers with organic fertilizers can change the fungal community in tobacco leaves.The fungal diversity of tobacco leaves with the treatment of chicken manure was relatively rich.Although the application of straw decreased in richness,the diversity index was higher.Compared with the application of pure chemical fertilizer,the diversity of leaf fungus community in rapeseed cake fertilizer and cow manure decreased.It was also found that there were different abundance of pathogenic fungi in different treatments,including Magnaporthe,Monographella,Fusarium and Boeremia,which could cause rice or tobacco diseases.Although the number of strains isolated from the straw treatment group was the largest,the pathogen content decreased year by year.Chaetomium spp.,as fungal biocontrol agents,were higher in the straw treatment.It provides a good direction to promote the growth of tobacco plant and control tobacco disease in the future.Based on the analyses of soil fungi,N,P,K and other indicators,straw as organic fertilizer to substitute chemical fertilizer has a good prospect in tobacco cultivation.(2)Microbial community structure from tobacco infected with bacterial wilt and healthy tobaccoIn Fujian,tobacco bacterial wilt(TBW),as one of the important bacterial diseases of tobacco,occurs in a large area in Fujian and seriously affects the yield and quality of tobacco leaves.In order to study the influence of bacterial wilt on the microbial community of tobacco plant,this experiment started from two aspects of bacteria and fungi.We sampled roots,stems of tobacco and soil from both infected and healthy tobacco from two regions(Hulei and Shanghang)in Longyan.The results showed that the microbial communities of rhizosphere soil of tobacco plants in different sampling regions were quite different.The bacterial community structure of tobacco(especially the stem)was more affected by TBW,but the soil was less affected.The fungal community structure of tobacco was less affected by bacterial wilt and more affected by tissue.Ralstonia,the pathogenic bacteria of TBW,is abundant in the stems of diseased tobacco.In addition,Streptomyces,Pectobacterium and Comamonas have high content,which can decompose tobacco stalks to a certain extent and accelerate the onset of bacterial wilt.Plectosphaerella is a pathogenic fungus of various plants that causes root and fruit decay.However,its relative abundance in the stems of healthy tobacco plants is significantly higher,and it is negatively correlated with Ralstonia.There may be a competitive relationship between the two,which may provide a new way to inhibit and predict TBW.The contents of organic matter,total nitrogen,alkaline hydrolysis nitrogen and available phosphorus in the rhizosphere soil of the pathogenic tobacco plant were significantly lower than that of the healthy tobacco plant,which to some extent indicated the lack of nutrient elements in the soil,which would hinder the growth of the tobacco and increase the possibility of tobacco disease.Through redundancy analysis(RDA),it was found that C/N,available potassium,p H,total potassium,calcium,available phosphorus and magnesium were closely related to the microbial community. |
