| Tobacco black shank disease is a disease of worldwide with widespread distribution and serious harm.Therefore,the prevention of diseases has become the most important link in tobacco production.With the damage of chemical prevention to the environment and human beings,there is an urgent need for a safe and efficient prevention method.This moment,the use of plant rhizosphere bacteria to control tobacco black shank disease has become a research hotspot in biological control.Plant rhizosphere bacteria have the characteristics of potassium release,nitrogen fixation,root colonization,and secretion of antibacterial substances,which can not only promote the growth of plants,but also inhibit the pathogens to reduce diseases,mainly bacillus?Bacillus?,Burkholder?Burkholderia cepacia complex?and the like.This study was conducted determination of biological functionson Paenibacillus polymyxa strain H1-2;B.subtilis strain 3183 and strain 1441;Burkholderia cepacia complex strain G2-7,D2 and strain N7-8-17,such as antibacterial ability,etc.The effects of growth index of tobacco plants and the prevention evaluated of tobacco black shank disease on different strains and their combination,combination and optimization of additives were by indoor potted prevention disease and growth promotion tests.The main findings are as follows:1.Firstly,the biological functions of six strains were analyzed from the aspects of antibacterial activity,potassium release,nitrogen fixation and colonization ability.The antibacterial effect was found that strain G2-7 had a good antagonistic activity against the Phytophthora Parasitica Var.nicotianae.The antimicrobial diameter reaches 2cm,and the other strains antimicrobial diameter reache 11.5cm.Quantitative analysis of potassium showed that of the 6 strains,strain H1-2 had the strongest potassium releasing ability,and the effective potassium content reached 13.76mg/L.The other 5 strains The effective potassium content ranged from 0.59mg/L12.97 mg/L.The colonization capacity determined that the strains H1-2?N7-8-17 had strong colonization ability in the tobacco roots,and the colony concentration was 2.73×105cfu/mg?2.67×105cfu/mg;Analysis of root vigor showed that the treatment of strains G2-7 and H1-2 significantly enhanced the vigor of the roots,and the reduction strength reached 80?g g-1.h-1,80?g g-1.h-1.2.To comprehensively utilize the biological functions of each strain,to analyzed the effects of different strains and their combinations on the growth of tobacco seedlings and the control of black shank disease.In order to understand whether different strain treatments have a concentration effect,fist selected strain H1-2 for concentration effect measurement.Indoor pot experiments showed that different concentrations of H1-2 had different effects on tobacco growth and disease prevention,among which the concentration of bacteria was 108cfu/mL,at the maximum leaf width,maximum leaf length,plant height,and underground dry weight of tobacco compared with the control were increased by 17.91%,7.33%,15.63%,and 21.92%,and the control effect was 61.11%,which was significantly higher than the other two treatments.The result showed that the 108cfu/mL growth promoting effect and disease prevention effect were significantly better than the other two concentrations.Each strain was 1:1 combined and analyzed the effect of different strains and their combined strains on disease prevention and promotion at concentration of 10 cfu/mL.The result showed that the strain H-2:G2-7?1:1?prevented effect was best reached 68.09%.Its maximum leaf width,maximum leaf length,plant height,ground dry weight,and underground dry weight compared with the control were increased by 22.08%,6.64%,15.83%,37.47%,and 41.75%,which were higher than other combinations and single strain treatment.It showed that the strain H1-2:G2-7?1:1?had the strongest preventive and growth promoting effects.2.In order to prolong the storage period of bacteria and improve the disease preventive effect of datian,L18?35?experimental design was adopted to select strain H1-2 to optimize various additives.The result showed that the optimized form for the five additives was 0.5%of HZSN,2%of CMC-Na,2%of MHA,1%of FZS,and 2%of MHJ.To understand whether the optimize additive and the combination strain H1-2/G2-7 have an promoting effect growth and disease preventive effect on tobacco,the respective additives and the combination strain H1-2/G2-7 to proportione according to the above ratio,analysis the effect of preventing disease and promoting growth of different treatments.As a result it was found that the maximum leaf width,the maximum leaf length,the plant height,the above ground dry weight,and the underground dry weight of the tobacco seedlings were significantly different from those of the control,which were increased by 29.38%?13.99%?26.80%?41.88%?51.71%.The maximum leaf length and plant height were significantly higher than other treatments.From the control effect,it was found that the optimized additive and combined strain H1-2/G2-7 reached 76.73%,and other treatment control effects reached59.58%70.07%,indicating that the additive and the combination strain H1-2/G2-7 ratio can significantly enhance the growth of tobacco and black shank disease prevention.4.Disease prevention and growth promotion in the field:additives with a combination strain H1-2/G2-7 were diluted at a concentration of 108cfu/mL,and field experiment on disease prevention and growth promotion in the field of tobacco black shank disease.The res ult showed that compared with the control the bacterial treatment had a significant effect on tobacco growth and the control of black shank disease.The plant height increased by 33.4%compared with the control,and the control effect was 73.47%.The result showed that the additive with the combination strain H1-2/G2-7 can significantly enhance the growth of tobacco and the resistance to black shank disease. |
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