Effects of Continuous Cropping on Soil Microbial Flora and Research Progress of Continuous Cropping Obstacle Reduction Techniques

Continuous cropping can bring economic benefits in a short time and meet the growing demand of agricultural products such as grain,but long-term continuous cropping will accelerate soil degradation,lead to the reduction of crop yield and the increase of disease rate,and destroy the balance of soil microbial structure.Therefore,it is not conducive to the sustainable development of soil ecosystem.In this paper,the problems caused by continuous cropping,such as imbalance of soil microbial flora,decrease of biodiversity,accumulation of root exudates and their effects on soil fertility and crop growth,were summarized,and some measures were suggested to alleviate the obstacles of continuous cropping,such as reasonable rotation,adjustment of intercropping planting mode and application of biological fertilizers.Moreover,the paper also looked forward to the development trend of continuous cropping obstacle reduction techniques,including the integration and application of biological techniques,the promotion of green ecological techniques and the application of intelligent management system.This study provides theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promote the healthy and sustainable development of modern agriculture.

Impact of Continuous Cropping on Soil Phenolic Acid Substances and Research Progress on Continuous Cropping Obstacle Reduction Techniques

At present,long-term continuous cropping in agricultural production has formed a relatively common development trend.With the increase of continuous cropping years,soil phenolic acids are also affected to varying degrees.This paper summarized the effects of continuous cropping on soil phenolic acids and the research progress of continuous cropping obstacle reduction techniques,aiming at providing theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promoting the healthy and sustainable development of modern agriculture.

Research Progress on Effects of Continuous Cropping on Soil Microbial Florae and Its Restoration

Continuous cropping has become a common form of agricultural production at present, but with the increase of continuous cropping years, continuous cropping obstacles such as soil-borne diseases and plant growth potential decline are becoming more and more common. At present, the causes of continuous cropping obstacles and continuous cropping restoration have become a hot issue in agricultural research. This paper summarized the effects of continuous cropping obstacles on soil microbial community structure and main technical methods to repair continuous cropping obstacles, such as agricultural measure management, microbial balance adjustment and soil improvement, aiming to provide theoretical reference for protecting the sustainable utilization of soil ecosystem and ensuring the stability of crop production.

Systematic Analysis of Gene Expression in Western Flower Thrip( Frankliniella occidentalis Pergande ) before and after Infection with Impatiens Necrotic Spot Virus(INSV)

Impatiens necrotic spot virus( INSV) is an important plant virus identified in recent years. Western flower thrip( Frankliniella occidentalis) has been confirmed to be the most efficient vector for INSV. In the present study,Illumina's second-generation sequencing technique was used to determine the variation in gene expression at the transcriptome level in western flower thrip before and after infection with INSV. By aligning 168 188 unigenes of western flower thrip to the NCBI protein database,47 558 unigenes were annotated,accounting for 28. 27% of the total. Species classification revealed that 58. 7% of the annotated unigenes of western flower thrip did not match any other species,and 15. 4% of had a match in Zootermopsis navadensis,12. 4% in Mus musculus,7. 3% in Mustela putorius,3. 4% in Theileria parva,and 2. 7% in Tribolium castaneum. By analyzing DEGs between INSV-free and INSV-carrying western flower thrips,we found that 11 genes were upregulated,and 9 genes were downregulated in western flower thrip after INSV infection. In addition,cell cycle and ubiquitin-proteasome pathway in western flower thrip were significantly infected by INSV infection.

Adsorption performance and mechanism of Schiff base functionalized polyamidoamine dendrimer/silica for aqueous Mn(Ⅱ) and Co(Ⅱ)

Schiff base functionalized polyamidoamine(PAMAM) dendrimer/silica were prepared for the adsorption of aqueous Mn(Ⅱ) and Co(Ⅱ).The effects that influence the adsorption were investigated systematically and the adsorption mechanism was illustrated by theoretical calculation.The optimum adsorption pH are 4 and 6 for Mn(II) and Co(Ⅱ).Adsorption kinetics follow pseudo-second-order model and the ratecontrolling step is film diffusion process.Adsorption isotherm shows that high initial metal ion concentration facilitates the uptake of metal ions.The adsorption capacity increases first and then decreases in the temperature range of 15-35℃.Density functional theory(DFT) calculation demonstrates that Schiff base functionalized PAMAM dendrimer tends to coordinate Mn(Ⅱ) and Co(Ⅱ) with the oxygen atoms of hydroxyl and carbonyl groups,nitrogen of tertiary amine and imino groups.The imino and tertiary amine groups mainly dominate the adsorption.The reproducibility of the adsorbents indicates they can be regenerated by 5% thiourea and 0.5 mol/L HNO_(3) solution efficiently.