Microbal Diversity In Continuous Cropped Tobacco Field And Application Of Microbial Agents

In the same field year after year planting the same crop or multiple cropping way called continuous cropping.Tobacco belongs to the genus Solanaceae,is a continuous crop.The effect of continuous cropping is not only the growth of plants,the shortness,the decrease of yield and quality,the deterioration of maturity and the long-term continuous cropping of soil physical and chemical properties and ecological environment.And the number of soil microbes changed,the number of carbon metabolism decreased,the structure of bacterial community changed,and the microecological imbalance of soil.Pests and diseases are increasing,the soil fertility is declining.And the current production is mainly dependent on the application of pesticides and fertilizers.This not only causes the increase of the input cost,the worse the quality of the tobacco leaves,pollutes the farmland soil and the water environment,and finally endangers human health.Therefore,the relationship between soil environment and soil microbial community structure was analyzed from the study of microbial community in continuous cropping tobacco fields.At the same time,the number and composition of rhizosphere microbes in continuous cropping tobacco fields were studied by pot experiment and field experiment,rhizosphere soil enzyme activity,soil pH and soil physical and chemical properties,in order to overcome the tobacco continuous cropping obstacles to provide theoretical guidance.In different cropping years,the microbial diversity of bacteria was higher in continuous cropping for four years.Fungi in the second consecutive year when the microbial diversity is higher.From the OTUs value,for a period of 4 years,the total number of bacteria in the sample was 3034,a total of OTUs were 228,the fifth consecutive year,the sixth year,the eighth year,the sample bacteria total OTUs value are 3429,sample fungus total OTUs value are 190.Indicating that with the increase in continuous cropping,microbial diversity decreased.At the level of the species distribution map,the higher abundance of bacteria was detected: the acid bacteria door,the strain of bacteria,Fungi abundance is higher: the combination of bacteria door,ascomycetes.In the cluster analysis,the similarity between bacteria and fungi was higher in the second year of continuous cropping and the third year of continuous cropping.The similarity between bacteria and fungi was the same in the first year and for more than three years.Based on the application of microbial agents in the laboratory to overcome the application of tobacco continuous cropping obstacle,a total of 12 microbiculate formulations were selected for the benefit and environment-friendly strains.Potted trials and field experiments were carried out for 4 years.The growth indexes and soil physical and chemical properties were analyzed at different stages of tobacco growth.Combining the results of pot experiment and field experiment,it is concluded that the formula is T5 and T10.Among them,the best is T5.The plant height of T5 in field was 126.70 cm,which was 9.78 % higher than that of the control.The stem diameter was 12.96 cm and 13.50 % higher than the control.From the incidence of tobacco,T5 incidence rate of 18.89 %,compared with the control decreased by 54.05%.The contents of soil organic matter and the contents of microorganisms such as bacteria,yeasts and actinomycetes were significantly higher than those of the control group,and the effect of T5 was the most obvious.