Study On The Three Kinds Of Fumigants For The Prevention And Control Of Pestilence And Soil Biological Properties

Greenhouse soil provided by Shanxi Kunrun Modern Agriculture Co.,Ltd in Jiaocheng county of Shanxi province was applied as experimental soil for the pot experiment.With pepper as the experimental crop,influences of three kinds of fumigants including methyl iodide,ammonia water and dazomet on pepper in terms of its epidemic treatment,growth,output and quality were researched in this article.By adopting indoor culture experiments,influences of these three fumigants on enzymatic activity,PLFA content and microbial biomass C and N of soil were studied,for the purpose of screening the fumigants appropriate to be popularized and utilized in this region and providing the scientific basis for the prevention and treatment of soil-borne diseases.Research results are as follows:1.Treating soil respectively by fumigants of methyl iodide,ammonia water and dazomet all achieved a lower morbidity and disease index for pepper than that for PCK treatment.However,their control effects were higher than that for PCK treatment.During the same period,with the increase of the fumigant concentration,morbidity and disease index of pepper would be declined while the control effect of pepper diseases would see an increase.For the same treatment,with the extension of time,both the morbidity and disease index of pepper would be raised,giving rise to non-significant differences for the control effect of pepper diseases.Among all the treatments,treatment by high concentration of dazomet(PM3 treatment)ranked the bottom in the morbidity and disease index of pepper,indicating the best control effect.The morbidity and disease index of pepper had been controlled within 5%during the entire period of the experiment,ensuring a control effect above 94%.2.Treating soil respectively by fumigants of methyl iodide,ammonia water and dazomet could all promote the growth of pepper.The chlorophyll content of pepper leaves and height of pepper plants during the seedling and mature stages were higher than that for PCK treatment.With the rising of the fumigant concentration,the chlorophyll content of pepper leaves and height of pepper plants during the seedling and mature stages would be increased accordingly.Among all the treatments,treatment by high concentration of methyl iodide((PD3 treatment))ranked the top in the chlorophyll content of pepper leaves,higher than that for PCK treatment by 0.96 times.PM3 treatment presented the highest pepper plants during the seedling and mature stages,respectively higher than that for PCK treatment by 1.26 times and 0.82 times.The root activity of pepper for each treatment would decrease with the rising of the fumigant concentration.The root activities of pepper as a result of PD 1,PD2,PA 1,PA2,PM1 and PM2 treatments were all significantly higher than that for PCK treatment.However,the root activities of pepper resulting from PD3,PA3 and PM3 treatments were lower than that for PCK treatment.PMI treatment ranked the top among all the treatments in the root activity of pepper,exceeding that for PCK treatment by 24.85%.3.Treating soil respectively by fumigants of methyl iodide,ammonia water and dazomet could enhance the output and quality of pepper.The output,Vc content and soluble sugar content for each fumigant treatment were higher than that for PCK treatment.Among all the treatments,PM3 treatment achieved the highest pepper output and content of soluble sugar,higher than that for PCK treatment by 162.21%and 90.84%.PD3 treatment ranked the top in the Vc content of pepper fruits,higher than that for PCK treatment by 74.77%.The nitrate content for each fumigant treatment was lower than that for PCK treatment.Meanwhile,the nitrate content of pepper fruits would be decreased with the increase of the fumigant concentration.PM3 treatment presented the least nitrate content,lower than that for PCK treatment by 53.42%.4.By adopting fumigants of methyl iodide,ammonia water and dazomet to treat soil,in the event where the recovery day for the microorganism was zero,the contents of soil microbial biomass C and N were remarkably lower than that for SCK treatment.And with the rising of the fumigant concentration,the contents of soil microbial biomass C and N were lowered.SM3 treatment achieved the least contents of soil microbial biomass C and N among all the treatments,respectively decreased by 82.59%and 85.88%compared to that for SCK treatment and exerting the biggest influences on the contents of soil microbial biomass C and N.5.By adopting fumigants of methyl iodide,ammonia water and dazomet to treat soil,in the event where the recovery day for the microorganism was zero,the bacteria PLFA content,fungus PLEA content,actinomycetes PLFA content and total PLFA content for each treatment were lower than that for SCK treatment.Moreover,the higher the fumigant concentration was,the lower the above contents would be.Among all the treatments,SM3 treatment ranked the bottom in the bacteria PLFA content,fungus PLFA content,actinomycetes PLFA content and total PLFA content,respectively declined by 74.35%,68.55%,75.55%and 51.05%compared to SCK treatment and exerting the biggest influences on PLFA of soil.6.By adopting fumigants of methyl iodide,ammonia water and dazomet to treat soil,the sucrose activity of soil as a result of SD1 and SA1 treatments would present itself as the following process:activation-inhibition-activation-recovery.While the sucrose activity of soil resulting from the treatments of SD2,SD3,SA2,SA3,SM1,and SM2 was presented as:activation-inhibition-recovery.Each treatment would affect the soil phosphatase activity as:inhibition-activation-recovery.And the urease activity produced by each treatment would experience the process as:inhibition-recovery.Combined with the economic benefit analysis,three kinds of fumigant dazomet effect is best,methyl iodide,ammonia is poorer,PM3 is the best choose fumigation processing.