| In China’s current tobacco planting system,continuous cropping of tobacco has become a kind of pattern that can not be ignored.However,the long term continuous cropping of tobacco will lead to the change of the original habitat of tobacco planting soil,and cause a series of problems,for example,poor growth,the quality is reduced,the yield is decreased and the resistance is poor.It is very important to regulate the planting system and reduce the harm of tobacco continuous cropping.Soil factors including soil chemical substances and soil enzymes.Based on the actual production of tobacco in Henan,Luohe,in Tobacco Science and Technology Park Yancheng district,studied The continuous cropping soil of flue-cured tobacco,tobacco of Yuyan 6 as test material,study on the effects of continuous cropping on soil factors and the effects of continuous cropping on soil enzyme activities and microbial activities of root system combined with high throughput sequencing technology,for the redundancy analysis on soil environmental data,high throughput sequencing of bacteria and fungi in soil samples,to accomplish the analysis of microbial diversity in tobacco growing soil.The main results are as follows:1.Earthworm manure could adjust the acidity and alkalinity of continuous cropping soil,so that the continuous cropping soil decreased from p H 7.5 to p H 7.2.Microbial fertilizer could significantly increase soil available nitrogen and available phosphorus content.Compared with CK,the contents of available nitrogen,available phosphorus and available potassium in soil were significantly different in the two kinds of fertilizer mixed treatment,but the effect on the content of organic matter was not obvious.Compared with CK,different fertilization treatments had a significant effect on soil enzyme activities.The activities of enzymes in soil samples were significantly enhanced by T3 treatment,especially urease,which increased by 36.68%~157.27%.The effect of mixed application of two fertilizers was the most significant.Canonical correlation analysis showed that,the most significant factors affecting soil fertility were urease and alkali hydrolyzable nitrogen.Nitrogen content in tobacco growing soil is the key factor affecting soil quality.Factor analysis showed,the higher load on the first principal component of five indexes of urease,phosphatase,alkali hydrolyzable nitrogen,catalase and available potassium could be used to characterize soil fertility to some extent.Soil enzyme activity and soil physical and chemical factors can be used to evaluate soil fertility in common.Principal component analysis showed,the soil environment system could be divided into 4 small systems,in which the soil carbon level system had the greatest influence,and the soil organic matter content can significantly affect other soil factors.2.The analysis of soil microbial biomass indicated that,the number of bacteria in different treatments was increased with the post transplant period,showed a trend of first rising and then decreasing.Different fertilization treatments were beneficial to increase the number of bacteria.The total number of fungi showed a downward trend.Compared with the contrast,different fertilization treatments could reduce the number of soil fungi.Comparison of each treatment,earthworm manure was conducive to the increase in the number of bacteria,microbial fertilizer was beneficial to reduce the quantity of fungi.The effect of the combination of the two was more balanced,which could alleviate the phenomenon of soil microbial imbalance.3.High throughput sequencing of soil bacteria 16 S r DNA V4 region,1.60×106 sequences,and 2.02×109 bases were obtained.Tobacco grown soil containing 41 phylum of bacteria,distributed in 120 classes and 274 genera which species is very abundant.Continuous cropping tobacco planting soil,some bacterial populations had gradually became dominant groups,for a larger percentage.And some trace species gradually disappeared,Soil bacterial community structure changed greatly under the condition of continuous cropping,single cropping and fertilization.Each sample had a considerable number of unique OTUs,but the number of OTUs was not very different in general.OTUs heatmap image also showed the different treatments of bacterial community composition and dominant flora had little difference.4.High throughput sequencing of soil fungi 16 S r DNA-ITS region,1.11×106 sequences,and 1.15×109 bases were obtained.Tobacco grown soil containing 5 phylum of fungi,distributed in 16 classes and 35 genera.The advantage of the dominant bacteria was apparently.The proportion of the different samples in the Ascomycota could reach more than 90%.Fungal community had some structural stability and similarity.It is found that there are common pathogens in the rhizosphere soil of tobacco,such as Fusarium,Colletotrichum,Alternaria,Aspergillus and Penicillium.The diversity index and abundance index of the fungi community decreased with the application of soil modified fertilizers,the content of fungi in the soil containing a large number of soil borne pathogens in the family of tobacco plants was decreased.5.Redundancy analysis showed,the main factors affecting soil microbial abundance were soil p H and soil carbon.The abundance of bacterial community was mainly affected by organic matter content and amylase activity,was a positive correlation.Soil urease activity was negatively correlated with bacterial community diversity.The content of alkali hydrolyzable nitrogen and available phosphorus in soil was negatively correlated with the diversity index.The content of nitrogen and phosphorus in soil was the limiting factor of soil fungal community.The activity of invertase and amylase increased,which could promote the diversity of fungal community.In sum,continuous cropping system reduced the quality of Flue-cured Tobacco,broke the balance of soil environmental system in addition.It also reduced the ability of the soil to self repair,greatly changed the diversity of soil fungal community structure.However,the diversity of bacterial community structure had little influenced and a greater impacted on the abundance.The effects of continuous cropping of flue-cured tobacco on soil environment and rhizosphere microorganisms in Luohe tobacco growing areas were analyzed of wormcast and microbial fertilizer.This paper suggested that these two fertilizers could alleviate the continuous cropping obstacle to a certain... |
