Preliminary Study On Consecutive Monoculture Problem And Reduction Techniques In Flue-cured Tobacco

Pool-culture and field experiments were used to study the effect ofcontinuous cropping on the growth, the physics and chemistry character of soilplanting tobacco, and discuss the improvement effect of different control techniqueson the tobacco growth, development and quality of continuous cropping flue-curedtobacco. Meanwhile the physics and chemistry character of continuous cropping soilwere investigated. It would offer some effective technologies for the abatementtechnology of continuous cropping of flue-cured tobacco, furthermore for thesustainable development of the tobacco produces in Dali tobacco areas. The resultswere mainly summarized as below:1The effect of continuous cropping on tobacco in Dali tobacco areas1.1The effects of different years of continuous cropping on growth anddevelopment of cured-tobacco were different. Generally with the continuous croppingyears increasing, the trends of the growth of flue-cured tobacco became weak. Growthconditions of the first cropping was much better than that of2years continuouscropping and5years cropping. While Growth conditions of2years continuouscropping was significantly better than that of5years of cropping,1.2In this study, with the continuous cropping years increasing,the trends of theyield and value of flue-cured tobacco were firstly increased and then decreased, butfor the trends of the ratio of mid-high grade leaves and average price of tobacco weredownward. The results explained the continuous cropping can improve the tobaccoproduction in the short term. But it could be seen when the continuous croppingincreasing, the tobacco growing worse in the long term. It also could decline thetobacco production and quality and reduce the economic efficiency.1.3The long-term continuous cropping could reduce the content of total sugar,revivification sugar and potassium, but increase the content of nicotine and decrease coordination deteriorates in the tobacco. With the increase of continuous cropping,the content of revivification sugar, total sugar and potassium all had a downwardtrend in the tobacco middle leaves, While the content of nicotine had a rise one. Theratio of Sugar nicotine and Potassium chloride in that of5years continuous croppingwere the lowest.1.4With continuous cropping increasing, the trends of number of the bacteria,fungi and actinomycetes first increased then decreased. The results of BIOLOGanalysis were similar to traditional soil microbial culture, the trend of rhizospheremicrobial growth also first increased then decreased as the continuous croppingincreased. The flue-cured tobacco rhizosphere soil of2years continuous cropping wasbeneficial for the Microorganism which used the carbon as microbial growth substrate,such as carboxylic acids derivatives, polymers, carbohydrates, phenolic acids, aminoacids and amides. While the flue-cured tobacco rhizosphere soil of first corpping wascarbohydrates carboxylic acids derivatives, carbohydrates, amino acids and amides.The sequence of degree of phenolic acids utilization was:2years>5years>the firstcropping. It was to say there was more phenolic acids and Pathogenic microorganismsin the continuous cropping.1.5From the point of the rhizosphere soil texture related activities, withcontinuous cropping increasing, the trends of urease and cellulase activities firstincreased then decreased, but the trends of invertase and acid phosphatase activitiesfirst decreased then increased. Compare with the2and5years continuous cropping,the activities of dehydrogenase, peroxidase, polyphenol oxidase were substantiallylower in the first cropoing. to some extent, explain, the tobacco planting soilaccumulated much harmful substances and stimulated the Enzyme activities whichrelated to improving soil texture.2The effect of different restoration techniques on continuous cropping oftobacco in Dali tobacco areas2.1The experiment was conducted in2012and2013. The treatments ofquicklime (900kg/hm2), calcium cyanamide (375kg/hm2) and microbial agents (210kg/hm2) could significantly improve cropping tobacco growth and promote tobacco strains growth.2.2The treatments of quicklime, calcium cyanamide and microbial agents couldsignificantly improve the economic characters of flue-cured tobacco. Compare thedifferent treaments, the best one was calcium cyanamide, Whose production value,average price, the middle and highest proportion of smoke and the yield were highest.Meanwhile there were significantly differences among the calcium cyanamide to themicrobial agents, quicklime and the contrast for the tobacco yield and output value.2.3The treatments of calcium cyanamide and microbial agents effectivelyimproved the content of central smoke revivification sugar, total sugar and potassium,reduced the chlorine. The main chemical components of tobacco became morecoordination. The ratio of sugar nicotine and Potassium chloride in the treatment ofcalcium cyanamide and microbial agents higher than that of the contrast. Inconclusion, the treatments of calcium cyanamide and microbial agents were betterthan that of the contrast, whose chemical composition of flue-cured tobacco weremore coordination.2.4To a certain extent, the applications of quicklime, calcium cyanamide andmicrobial agents could improved the microorganisms number and microbialdiversities in the flue-cured tobacco rhizosphere soil.The number of microorganismsin the contrast was lower than that of quicklime, calcium cyanamide and microbialagents. It was to say these three treatments can improved the microorganisms numberin the flue-cured tobacco rhizosphere soil.In a word, the treatments of quicklime,calcium cyanamide and microbial agents could improve the rhizosphere microbialdiversities by the BIOLOG analysis, especially quicklime and calcium cyanamide.2.5In some extent, the treatments of quicklime, calcium cyanamide andmicrobial agents could improve the enzyme activities and soil nutrients for theflue-cured tobacco rhizosphere soil. The treatments of quicklime, calcium cyanamideand microbial agents also could improve the activities of urease, sucrase, polyphenoloxidase, catalase and peroxidase in soil; the treatments of quicklime and microbialagents improved the activities of phosphatase and dehydrogenase, but reduced thecellulase activities in soil. In summary, the different restoration techniques of quicklime (900kg/hm2),calcium cyanamide (375kg/hm2) and microbial agents (210kg/hm2) could improvethe quantities and diversities of the flue-cured tobacco rhizosphere microbial,increased the soil enzyme activities, promoted tobacco plant growth, increased theyield and quality of flue-cured tobacco. It can be further promoted.for practice infuture.