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- Abstract：Understanding how effective protective memory responses are produced in coccidiosis and how to design a successful anticoccidial vaccine are long goals in the coccidiosis research area. This study summarizes research progresses in the last 50 years and pinpoints possible directions to guide novel anticoccidial vaccine design. The assumption and new strategy are based on the three key points of generating efficient protective memory immune response, namly, threshold, effect site and time of generating protective immune level. The results show that: 1)Differences should be noted between the immune responses induced by infections and antigens delivered either as recombinant proteins, DNA or live vectors. Live oocysts vaccine can induce protective memory immune responses, rendering the infected hosts to a ‘Primed' immune state(that is, the immune system can quickly and efficiently recognize hundreds of coccidian antigen and have higher resistance to reinfection by coccidia); Non-live oocyst vaccine may fail to develop protective memory responses, and the vaccinated hosts are in immune ‘Naive' state(that is, the immune system can only recognize one or several specific coccidian antigens, and its ability ro resist reinfection by coccidia is not effective to resist pathogen infection). This also explains the limited success achieved in developing new anticoccidial vaccines. 2)The primed immune state originated from multiple players, including tissue resident memory cells(TRM), circulating effector memory T cells(TEM), central memory T cells(TCM), etc. , which can inhibit the infection at an early stage. How to develop vaccines inducing effective memory cells, especially TRM cells which populate the front line of coccidia infection, is key to achieve primed immune states for vaccinated hosts. Targeting antigen-experienced DCs to the gut offers a tremendous potential. 3)Inhibiting early schizogenesis of coccidian is an important feature of a ‘primed' host to resist coccidiosis, which provides a new idea for evaluating high-efficient coccidian vaccine. In summary, only when we fully understand how to achieve the ‘primed' immune state after infection or vaccination, can the scientific prevention and control of coccidiosis be realized.Keywords：coccidiosis;anticoccidial vaccine;naive;primed;gut-resident memory T cell13|11|4<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to improve the antibacterial and therapeutic effect of bacteriophages against intracellular bacteria, the literature review method was used to retrieve the relevant literatures on carrier mediated phages entry into cells in recent years. The functional development, experimental techniques and application prospects of carrier mediated into cells were summarized and discussed. The results showed that: 1)Bacteriophages, as a class of viruses, can infect and lyse bacteria. The natural antibacterial properties of phages make them widely studied as alternatives to antibiotics. However, the basic research of bacteriophage on intracellular bacteria is abundant in foreign countries, but few in China. 2)Compared with free phages, using inorganic nanoparticles, liposomes as carriers to mediate phage delivery can effectively improve the efficiency of phage entry into cells, and prevent phages from being cleared by the host immune system and avoid the influence of intracellular environment. 3)Liposome has become the most widely studied phage carrier into cell. Because it can effectively improve phage entry efficiency and bactericidal efficiency as a carrier. Therefore, this paper reviews the recent research progress of carrier mediated phage entry and anti-intracellular bacteria, and expounds the different carrier mediated characteristics, the mechanism of entry into the cell and how to improve the efficiency of entry. Finally, the present problems and development prospects are prospected, in order to provide reference and theoretical support for solving practical problems of intracellular bacterial infection by efficient delivery of phages with carrier delivery system.Keywords：bacteriophage;carrier delivery system;intracellular bacteria;antibacterial activity16|9|1<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to analyze the application and development potential of pose estimation in animal behavior recognition and animal welfare research, this paper took the deep learning-based pose estimation method as a breakthrough, summarized the research progress and directions of animal pose estimation from the perspective of two-dimensional and three-dimensional space, and introduced the common data sets and evaluation indexes. Then integrated the research results related to animal behavior recognition based on pose estimation, focused on the algorithms of keypoint detection and behavior classification and their features. Pose estimation provides skeleton information and motion features for tasks such as action recognition and behavior analysis, and became a non-contact monitoring method for animal behavior recognition and abnormal information warning. However, due to the limitation of small training data set, the research and development of animal pose estimation was relatively slow compared to human pose estimation. Therefore, the used of cross-domain learning to further improve its performance has become an emerging tool in recent years. This review expands research ideas and research methods for researchers related to intelligent animal behavior recognition, animal welfare research, and smart farming.Keywords：animal behavior recognition;health monitoring;pose estimation;keypoints detection;behavior classification12|11|7<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to deeply understand the research information and development trends related to microplastic pollution in soil, VOSviewer and CiteSpace were used to collate the published research results in the field of soil microplastic pollution in CNKI and Web of Science databases from 2000 to May 2022, and analyzed them in terms of the number of articles published, journals published, authors and affiliations, countries/regions, keywords and co-citation information. The bibliometric analysis results showed that: 1)The volume of literature in the previous period fluctuated slightly and the reaearch heat continued to increase after 2018; The Northwest Agriculture and Forestry University, the Wageningen University Research Centre, and the Chinese Academy of Sciences have issued the largest number of papers in this field. 2)Farmland soil is the most representative type of soil. In addition, microplastic pollution in deserts, wetlands and mountains has been highly concerned by scholars at home and abroad. 3)The research directions in this field include the mode of entry of microplastics into terrestrial soils and the characteristics of their abundance distribution in soils, the selection and optimization of microplastic detection technology in soil samples, microplastics as carriers to adsorb and transport heavy metals and dissolved organic matter in soil, and possible harmful effects of microplastics on organisms transmitted through the food chain, etc. 4)From the perspective of research hotspots, the research object of microplastic pollution in soil has gradually expanded from agricultural soils to a wide range of soil types and remote areas. The concentration transport and size selection mechanism of microplastics in various soils and their applicable detection methods have been further developed. The analysis and testing of microplastics with different particle size ranges in soil has developed into a more subdivided research program. Especially the assessment of the risk of microplastics in soil and the analysis of the potential hazards of microplastics from soil entering different tissues of plants and animals and organs of the human from the microscopic perspective of cells, molecules and genes have become a new research hotspot in the field. The results of bibliometrics analysis in this paper can provide reference for the in-depth study of microplastic pollution in soil.Keywords：soil;micro-plastic;visual analysis;knowledge graph;bibliometrics11|14|3<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to understand the hot trends of tea drought research at home and abroad, and clarify the development of the history of tea drought research and look forward to the development prospects of tea drought research in the future, in the study, bibliometrics method and CiteSpace 5. 7. R5 software were used to study literatures related to tea plant drought published from 1990 to 2021 in CNKI and Web of Science databases for understanding the dynamics of hotspots, the historical development and the development prospects of tea plant drought research in China and abroad. The number of published papers, journal sources, co-authors and citation of tea plant drought research at home and abroad were analyzed. The results show that in the field of tea plant drought research, the number of publications in Web of Science and CNKI databases show an overall upward trend. Most of the authors with the highest number of publications are from China, and the main research institutions are also from Chinese research institutes and universities. At present, the research on the molecular level of drought stress in tea plants is a hot field in the world. The sequencing of tea plant genome has been completed and with the continuous improvement of tea plant genome annotation information, the research on the molecular mechanism of tea plant drought resistance will still be a hot spot in the future. Meanwhile, this study provides one of the key points for future work for researchers in the field of tea drought research: to strengthen the study on the coupling effects of two-factor or even multi-factor stress during the occurrence of tea drought.Keywords：tea plant;drought;CiteSpace;research trends;research hotspots8|15|5<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：Orchidaceae, commonly known as orchids, is the most important ornamental flowers. Constructing genetic maps, especially high-density genetic maps, can improve breeding level, this paper reviewed the genetic map and QTL mapping of important traits of Orchidaceae plants. The results showed that: 1)Since the first genetic map of Dendrobium in Orchidaceae was published in 2007, a total of 13 linkage maps of Orchidaceae plants have been published. 2)In terms of map type, 5 maps are for inter-cultivar mapping and 8 maps are for inter-species mapping. In terms of map usage, 7 maps could be used for QTL mapping and 3 maps could be used for fine mapping or gene cloning. 3)According to the constructed genetic map of Orchidaceae, the total map distance is higher and the average map distance is smaller which lays a foundation for the practical application of the map. However, the small mapping population is always a problem. 4)Although QTLs are mapped for leaf and flower color of Phalaenopsis, sepal size and stem and total polysaccharide contents of Dendrobium, but it is not involved in flower size, flower number, flower fragrance, flower type, flower spot, plant resistance and so on. Therefore, the construction of genetic map, especially the high-density genetic map can provide reference for the biological research and molecular marker-assisted breeding.Keywords：Orchidaceae;genetic maps;QTL mapping14|12|4<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to explore and utilize agricultural management measures with high carbon sequestration and low emissions, summer maize production in the North China Plain was taken as the research object. Based on field experiments and life cycle assessment methods, five nitrogen application treatments including control check(CK), low nitrogen fertilization(LF), suitable fertilizer utilization(SU), emission reduction(suitable nitrogen with inhibitor, ER)and high nitrogen fertilizer(HF)were conducted to quantitatively evaluate the warming potentials of soil greenhouse gas emissions, agricultural inputs(GWPIndirect), and net primary productivity(GWPNPP). The net comprehensive warming potential(Net GWP)and the economic benefits in the whole process of summer maize production were also investigated. The results showed that: The total warming potential(GWPSoil+GWPIndirect)of emissions ranged from 10 831. 3 to 14 301. 9 kg/hm2(measured in CO2 equivalent)under different treatments, with HF>SU>LF>ER>CK in descending order. The GWPSoil and GWPIndirect of HF were the highest, 10. 9% and 153. 3% higher than those of CK, respectively. GWPSoil made major contributions to the total emissions(>70%), while fertilizer contributed the most to GWPIndirect in agricultural inputs, accounting for 54. 1% to 69. 7%(except CK), followed by irrigation. The Net GWP of summer maize farmland in North China Plain was negative, which was the carbon sink of the atmosphere. SU and ER treatments had the largest Net GWP, which was 18. 1% and 17. 9% higher than CK treatment, respectively. To sum up, the net profits of ER and SU treatments were the highest and these two treatments belonged to the high yield-high Net GWP planting management mode. However, the GWPSoil value of ER reduced by 8. 7% compared with SU treatment. Therefore, ER treatment was more conducive to realize greenhouse gas emission reduction and suitable to be promoted as a green agricultural development mode in the North China Plain.Keywords：North China Plain;summer maize;greenhouse gases;life cycle;global warming potential11|12|4<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：This study aimed to explore the effects of different root distances between maize and neighboring maize or faba bean on maize(growth and phosphorus(P)uptake). The target maize was planted in a cirlindrical rhizo-box in single or monocropped with maize or intercropped with faba bean with different root distances under low P conditions. The P content, biomass and rhizosphere process of plants in different treatments were determined. The results showed that: 1)Compared with the single maize, there was competition between the target maize and neighboring plants regardless of the neighbouring plant species was monocropped maize or intercropped faba bean. When the root distance between the monocropped maize was close, the biomass and P contents of monocropped maize decreased by 21% and 33%, respectively, while that of intercropped maize decreased by 34% and 31%; respectively. When the distance between neighboring plants was large, the biomass and P contents of monocropped maize decreased by 10% and 15%, respectively, while that of intercropped maize decreased by 29% and 29%, respectively. 2)When the root distance between maize and faba bean was close, rhizosphere pH of faba bean was significantly higher than maize, but there was no significant difference between plants in intercropped treatments with large distance. Moreover, when the root distance between maize and faba bean was large, the rhizosphere carboxylates concentration of intercropped maize was higher than monocropped maize, while there was no significant difference in the treatments with close root distance. 3)There were no significant differences in total root length and total root surface area of monocropped and intercropped maize under different treatments. In conclusion, under low P condition, the intraspecific competition intensity of monocropped maize decreased with the increase of root distance; but the intensity of interspecific competition between maize and faba bean was similar among different root distance treatments and there was no facilitative P uptake. The competitive and facilitative P uptake through interspecific rhizosphere interaction could depend on moderate soil P supply.Keywords：maize;faba bean;root distance;intercropping;phosphorus uptake22|11|2<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：The aims of this study were to clarify the carbon dynamics of farmland ecosystem, provide data support for the realization of low-carbon agriculture and ecological revitalization in Heilongjiang and help achieve carbon peak and neutrality targets in China. Based on the agricultural production input data of 13 cities in Heilongjiang from 2000 to 2020, a carbon footprint model of farmland ecosystem was constructed. The spatial and temporal changes of carbon footprint of farmland ecosystem were analyzed, and the spatial correlation of carbon emissions of farmland ecosystem were analyzed by ArcGIS. The results showed that: The carbon absorption and carbon emissions of farmland ecosystem presented an increasing trend. The carbon footprint displayed fluctuation characteristics, which was spatially “high in the southwest and low in the northeast”. The farmland ecosystem in Heilongjiang showed a carbon ecological deficit and played a carbon source function. The carbon ecological surplus showed an increasing trend since 2010, the carbon source function continued to be weak. Therefore, strategies and suggestions for strengthening field management and realizing carbon sequestration and emission reduction in farmland were proposed in a targeted manner.Keywords：carbon footprint;carbon emissions;carbon absorption;farmland ecosystem;spatial-temporal evolution;Heilongjiang10|14|11<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to explore the allelopathy of wheat straw and extract on weeds in foxtail millet fields, four treatments of wheat straw aqueous extract 1(T1), 2(T2), 10(T3), 100 g/L(T4)and control(CK1, 0 g/L)were set up to determine their effects on seed germination rate, root length, bud length, germination allelopathy index, root length allelopathy index, bud length allelopathy index and comprehensive allelopathy index of four weeds Echinochloa crusgalli (L. )Beauv, Amaranthus retroflexus L. , Setaria viridis(L. )Beauv and Chenopodium album L. In the field experiment, four wheat straw mulching treatments 0(CK), 2 250(W1), 4 500(W2), 9 000 kg/hm2(W3)and three plastic film mulching treatments 50%(P1), 70%(P2), 100%(P3)were set up to measure the number, density, coverage and control effect of 4 kinds of weeds in the field. The results show that the water extract of wheat straw treated with T4 had the highest allelopathic index and the strongest allelopathic inhibition effect on the seeds of four kinds of weeds in the foxtail millet field. The inhibition effect on the seed germination of four kinds of weeds from high to low was as follows: C. album>A. retroflexus>S. viridis>E. crusgalli. And the allelopathy index were respectively -0. 85, -0. 77, -0. 71 and -0. 34; T1 showed allelopathic promoting effect on the germination of weed seeds of C. album, S. viridis and A. retroflexus, and the promoting effect from strong to weak was as follows: S. viridis(0. 14)>C. album(0. 05)>A. retroflexus(0. 02). And the allelopathic inhibiting effect was discovered on the germination of E. crusgalli seeds; T2 showed allelopathic promotion on the bud length of four weeds; T3 showed allelopathic inhibition on root length of S. viridis and E. crusgalli and allelopathic promotion on C. album and A. retroflexus; the allelopathic effects of T4 on four kinds of cereal weeds from high to low was: S. viridis>A. retroflexus>C. album>E. crusgalli. Compared with the treatment without straw mulch, the occurrence density of C. album decreased respectively by 69. 39%, 64. 29% and 43. 34% in W3(9 000 kg/hm2)after 3 times of moderate rain for five days, and the total coverage of weeds decreased by 22. 04%, 41. 98% and 12. 49% respectively. With the extension of straw mulching time, the number of rainfall increased, the density of weeds decreased first and then increased, and the coverage of weeds gradually decreased. With the increase of straw coverage from 2 250 to 9 000 kg/hm2, the control effect of weed plants increased from 20% to more than 60%. Therefore, the 100 g/L extract of wheat straw has the most significant inhibition effect on the seed germination, root length and bud length of four weeds, and 9 000 kg/hm2 wheat straw mulch can be used to control weeds in foxtail millet fields.13|9|6<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to explore the effects of endogenous hormone content on the grain-filling process of oat, 9 oat varieties with different genotypes were selected as experimental materials in 2020 and 2021. Field experiment was conducted to determine the grout grain weight, photosynthetic characteristics, leaf carbon metabolizing enzymes(sucrose phosphate synthase SPS, sucrose synthase SS)activity, auxin(IAA), gibberellin(GA3), zeaxin nucleoside(ZR), abscisic acid(ABA)contents and grain weight. The differences in physiological characteristics and endogenous hormones among different genotypes of oat at filling stage were investigated by variance analysis and cluster analysis. The results showed that: There were significant differences in the content of endogenous hormones and other physiological characteristics among different varieties(P<0. 05). According to the grout grain weight, oat varieties were divided into strong grout varieties and weak grout varieties. Among them, the varieties with stronger grain filling reached the peak filling stage earlier, and the grain filling started earlier than other varieties; grain weight fitting degree was better, the net photosynthetic rate and the activity of carbon metabolism enzymes during the grain filling process were higher, and the grain weight was better than other varieties. The grain weight per panicle of the varieties with stronger grain filling was 11. 8% to 176. 5% higher than that of the varieties with weak grain filling; the contents of IAA, GA3 and ZR in flag leaves of the strong grouted cultivars were respectively 12. 6% to 18. 2%, 7. 2% to 98. 0%, and 21. 4% to 72. 2% higher than those of the weak grouted cultivars. The contents of(GA3+ZR+IAA)/ABA were 39. 3% to 311. 9% higher than those of the weak grouted cultivars. Under the premise of the coordination of endogenous hormone levels, the contents of IAA and GA3 and grouting grain weight fitting degree displayed very significant positive correlation, which directly affected the grout grain weight, indirectly affected the activities of Pn and SPS, and regulated the synthesis of sucrose during grain filling, thereby affected the grain weight. In conclusion, during the grain filling process of oat, the appropriately increasing in the contents of IAA and GA3 in leaves has a positive effect on grain weight.Keywords：oat;endogenous hormones;grain filling stage;physiological characteristics;cluster analysis24|20|1<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to analyze the influence of coupling environmental factors on melon seedlings and realize the precise management of greenhouse melon environment. In the study, the daytime air temperature, carbon dioxide concentration and nutrient solution concentration were used as the regulatory factors, and the universal rotating combination design with three factors and five levels was adopted. The factor analysis method was introduced to extract the common factors of six growth indicators(total fresh weight, total dry weight, net photosynthetic rate, seedling index, leaf area and chlorophyll content), and the obtained common factors were used as the comprehensive evaluation index of seedlings. According to the evaluation value, the response model of integrated growth of melon seedlings to environmental factors was fitted, and the synergistic regulation of environmental factors was analyzed. The results showed that the coefficient of determination(R2)of the model was 0. 944, and the root mean square error(RMSE)was 0. 07, which was a good fit. In the experimental range, the effect of daytime air temperature on melon seedlings was greater than that of CO2 concentration and nutrient solution concentration. The comprehensive evaluation value of melon seedlings increased first and then decreased with the increases of CO2 concentration and nutrient solution concentration, and increased with the increase of temperature. The optimal combination of environmental factors for the comprehensive growth of melon seedlings was daytime air temperature 33 ℃-35 ℃, CO2 concentration 1 043-1 408 μmol/mol and nutrient solution concentration 2. 0-2. 9 mS/cm. This study can provide decision support for the optimization of environmental regulation of melon seedlings.Keywords：melon;orthogonal rotation;greenhouse environment;comprehensive evaluation index;model23|14|1<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：To investigate the impact of flowering characteristics and breeding system of Hemerocallis minor on its sexual reproduction process, in the study, the flowering characteristics and breeding system of H. minor through the determination and study of pollen activity change under different storage conditions and stigma receptivity, controlled pollination, pollen-ovules ratio(P/O)and out crossing index(OCI)were explored. The results indicated that: 1)The single flowering period was up to 20. 5-21. 5 h, and the group flowering period was about 60 days. 2)With the extension of pollen storage time, the pollen viability showed a decreasing trend. Under the same storage time and temperature, the pollen viability under dry condition was higher than that under non-dry condition. The best storage condition was -80 ℃ dry. 3)The receptivity of the stigma of H. minor showed a trend of rising first and then declining after flowering, and the fertile ability reached the highest after 3 h of flowering. 4)The breeding system type of H. minor was heterointer type, partially self-inbred affinity, and crossbreeding requried pollinators. Its pollen-ovules ratio(P/O)value was 2 364. 13±117. 39 and the out crossing index(OCI)value was 4. The results of this study provide a research basis for the addition of H. minor to Hemerocallis breeding and cultivating new varieties of Hemerocallis with early flowering and long flowering period.Keywords：Hemerocallis minor;pollen vitality;stigma receptivity;breeding system12|12|2<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：To select an appropriate process for gene differential expression analysis, the study analyzed the performance of three comparison tools TopHat2, HISAT2 and STAR and three differentially expressed gene screening tools DESeq2, edgeR and limma based on the fat transcriptome data of Songliao Black Pig and landrace pig, and comprehensively evaluated the performance in combination with the enrichment results of KEGG pathway. The results show that: 1)HISAT2 has the fastest running speed and STAR has the highest unique mapping ratio. After comprehensive consideration, this study selects HISAT2 data for subsequent screening and analysis of differentially expressed genes. 2)616 differential genes were screened by DESeq2, 890 differential genes were screened by edgeR and 829 differential genes were screened by limma, and 246 differential genes overlapped among the three. 3)The up-regulated differentially expressed genes of DESeq2, edgeR, and limma were enriched to 110, 108, and 142 pathways respectively, of which 72 were overlapped, while the down-regulated differentially expressed genes were enriched to 190, 247, and 177 pathways, of which 158 were overlapped. HISAT2 is recommended for genome mapping in this study. When there is no biological duplication, edgeR is recommended to screen differentially expressed genes. In order to reduce false positives during analysis, DESeq2 or the intersection of differentially expressed genes of two or more tools can be selected. The results of this study will help researchers obtain better and more comprehensive biological insights from transcriptome data.Keywords：differential expression;RNA-seq;analysis tools19|15|1<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to establish a culture scheme for rapid isolation of primary canine mammary epithelial cells, the study was to isolate canine mammary epithelial cells from the milk of healthy lactating golden retrievers, inoculate them with two different media and subculture them, and to explore the biological characteristics of cells in different media to provide simple and convenient isolation measures and suitable culture methods for canine mammary epithelial cells. The milk of golden retrievered dogs that had been lactating for one week was collected under sterile conditions, and mammary epithelial cells are obtained after centrifugation and cultured with complete and basal medium, respectively. Through morphological comparison and observation, the expression of cytokeratin 8 was detected by indirect immunofluorescence, and the growth curve of the third generation of mammary epithelial cells cultured in two kinds of media was drawn for investigating the cryopreservation and resuscitation activity of the 6th generation mammary epithelial cells cultured in complete medium. The results showed that: 1)A large number of cell clumps can be obtained by milk separation, and “fried egg-like” adherent cells appear after inoculation of both mediums, and both are highly expressed by cytokeratin 8 after digestion and passage. 2)The cells inoculated in the basal medium were mainly round monoclonal cell clumps gathered together in the early stage, and only a few cells survived in the fourth generation. With the increase of culture time, the cells became worse, and grew in a “cobblestone paving” shape, and the cell state was stable with the increase of passage times, and the cell growth curve presented a “S” shape. 3)After cryopreservation and recovery, the 6th genration mammary epithelial cultured in complete medium could adhere to the wall and and proliferate rapidly. In summary, the milk separation method successfully isolated the canine mammary epithelial cells. And compared with the basal medium, complete medium could better maintain cell activity, promote the proliferation and division of cells, and do not affect the viability of cell recovery after cryopreservation, providing an optimal culture scheme for rapid isolation of canine breast epithelial cells in the later stage.Keywords：canine mammary epithelial cell;milk separation;cytokeratin 8;cultivation optimization13|14|0<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order toidentity the pathogenic bacteria causing diarrhea and death of a racing pigeon in Nanjing, in the study, the pathogen from collected diseased materials were isolated and identified, the serotype, biofilm phenotype, virulence gene, and drug resistance spectrum of the pathogenic bacteria were analyzed, and artificial infection tests on the isolated strains were conducted. The results showed that: 1)The bacteria isolated from diseased pigeon tissues, swabs and feces were initially diagnosed as E. coli O157 in the laboratory. The isolated strains grew white and smooth round colonies on the NA plate and purple red colonies on the CT-SMAC plate. 2)The 16S rRNA gene sequence of the isolated strain was 98%-99% similar to that of Escherichia coli, and was named E. c. 86246. 3)The serological test showed that the isolated strain was Escherichia coli O157: non H7 strain, and the kinetic test further confirmed that it was a dynamic strain. 4)The isolated strain carriying tccp1014, eaeA and hly virulence genes can cause varying degrees of functional damage to the gastrointestinal tract of chicks, and even lead to death. Its median lethal dose was 2. 0×105 CFU/mL, with strong pathogenicity. 5)The isolated strain carries tetA, tetM, sul2, aadA1 and blaTEM resistance genes, had weak biofilm formation ability, and were severely resistant to tetracycline, aminoglycosides and other antimicrobial drugs, and were sensitive to amoxicillin, ofloxacin and norfloxacin. To sum up, the pigeon derived Escherichia coli O157: non H7 strain isolated in this study is mobile strain, has strong pathogenicity and certain drug resistance. The results provide theoretical basis and data reference for the epidemiological investigation, pathogenic mechanism analysis and precise treatment of antimicrobial drugs of Escherichia coli O157.24|24|3<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：Aiming at the problem of uneven distribution of solid inoculants directly added to the seedling substrate in the current production process of functional seedling substrates, based on a two-step compounding method, the mixing of γ-polyglutamic acid as inoculant carrier with traditional substrates was carried out. Single factor test and response surface analysis test were used to investigate the effects of carrier addition, seedling substrate moisture content, mixing speed and mixing time on the uniformity of Bacillus velezensis in seedling matrix. The results showed that the optimal mixing process parameters for the preparation of functional seedling substrates were as follows: The addition amount of γ-polyglutamic acid was 5. 6 g/L, the seedling substrate moisture content was 35%, the mixing speed was 42 r/min, and the mixing time was 333 s. Under the above conditions, the coefficient of variation of B. velezensis was 4. 59%. The optimized functional seedling matrix had no significant difference in bulk density and porosity with the traditional matrix, and the water-holding pore and maximum water-holding capacity of the matrix were increased by 5. 68% and 7. 92%, respectively.22|15|2<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：Aimed at the dynamic response problem of the leakage floor, the static analysis method is adopted to study the natural vibration characteristics of the leakage floor. The dynamic fundamental equations are established by considering compression and shear of foundation, translation and rotation inertia of beam with Timoshenko-Beam model and second-order effect of axial force. The dynamic displacement and internal force equations are derived. A method for analyzing the natural vibration characteristics of combined foundation beams is proposed, and the natural vibration period and mode shape of the floor are calculated. It results showed that: The period and mode shape of the combined foundation beam obviously differ from those of ordinary beams. Different structural parameters have different degrees of influence on the natural vibration period of the leakage floor, while the slats between the end joints do not change the vibration characteristics. The effects of bearing length and foundation stiffness are significant, the deviations caused by shear deformation, rotational inertia and foundation shear deformation are small and can be ignored. In conclusion, the geometric nonlinear dynamic combined foundation beam model is established, which can be used for comfort check and dynamic safety design of the piggery floor.Keywords：piggery;elastic foundation beam;leakage floor;inertial force;geometric nonlinearity;natural vibration characteristics10|12|0<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：Aiming at the problem of low uniformity during fertilizer application in the external grooved wheel fertilizer discharge device, an air-assisted centralized fertilization device and a synchronous fertilization control system were designed. The fertilization performance of three kinds of fertilization wheel structures, namely, straight groove, staggered groove and spiral groove, were compared using bench test, and the linear regression model between rotational speed and fertilizer discharge speed was established. Based on BDS and GPS system and limiting average filtering algorithm method, the fertilization control system was designed. The results showed that: 1)The fertilization performance was good for the spiral groove fertilization wheel at the fertilization speed of 10-60 r/min. The variation coefficients of stability the total fertilization quantity and consistency in each row were 0. 15% and 1. 57%, respectively. The variation coefficient of fertilization uniformity was <4%. 2)When the rotational speed of fertilization wheel is <60 r/min, the response time of fertilization control system was <0. 85 s. When the fertilization quantity and average operating speed were 300-600 kg/hm2 and 5. 22 km/h, respectively, the fertilization accuracy rate was >95%. In conclusion, synchronization, precision and uniform fertilizer application is achieved by the air-assisted centralized fertilization device and fertilizer application control system.Keywords：granular fertilizer;air-assisted centralized fertilization device;spiral groove fertilization wheel;synchronous control system;fertilization performance27|19|0<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to realize the rapid and accurate identification of nitrogen nutrition in rice, an improved VGG 16 network combined with transfer learning was used to diagnose and identify rice nitrogen nutrition. Nitrogen a application rates were respectively 0, 210, 300 and 390 kg/hm2 at the young panicle differentiation stage and full heading stage of rice. The rice leaf image data were obtained scanning and the data were then processed and expanded by image preprocessing. A network model was constructed by combining the improved VGG16 and transfer learning for the nitrogen nutrition diagnosis and identification of rice leaf image data. The results show that: 1)At the differentiation stage of young ears, the recognition accuracy of the improved VGG16 network is 93. 1%, the model size is about 1/6 of that of the transfer learning VGG16 model, and the training time is about 1 261 s. 2)The recognition accuracy of the model after fine-tuning can reach more than 95% in the young panicle differentiation and full heading stages of rice. In conclusion, the rice nitrogen nutrition diagnosis model based on transfer learning and the improved VGG16 network has good generalization ability, which can predict the nitrogen nutrition situation of rice, and can provide a reference for the nitrogen nutrition diagnosis of rice.Keywords：rice;nitrogen nutrition diagnosis;VGG16 network;transfer learning;fine-tuning26|16|9<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to explore the impact of herdsmen's livelihood capital and risk perception on the freezing-damaged livelihood risk in animal husbandry and its mechanism, based on the survey data of 644 herdsmen on 2020 in Ruoergai grassland located on the eastern edge of the Qinghai-Tibet plateau, this study constructs a theoretical analysis framework of “livelihood capital-risk perception-livelihood risk”, and uses the Tobit model, instrumental variables, mediation effects and other analysis methods to empirically test the effect of herdsmen's livelihood capital on the freezing-damaged livelihood risk from the perspective of risk perception's mediation effect. The results show that: 1)The livelihood capital significantly alleviates the impact of freezing-damaged livelihood risk in animal husbandry, specifically, physical capital and financial capital have a significant negative impact on it. 2)The risk perception of household has a significant positive effect on reducing the freezing-damaged livelihood risk in animal husbandry. 3)The risk perception of household has a significant mediation effect on livelihood capital's impact to freezing-damaged livelihood risk in animal husbandry, the mediating effect accounts for 13. 82% of the total effect. In conclusion, in order to reduce the freezing-damaged livelihood risk in animal husbandry, it is necessary to improve herdsmen's livelihood capital and risk perception, which could enhance the livelihood resilience of herdsmen and promote the high-quality development of grassland animal husbandry.Keywords：livelihood capital;livelihood risk;risk perception;grassland cold wave and snow freezing natural disaster;high-quality development of grassland animal husbandry8|11|4<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to explore the impact of livelihood capital on the relative poverty of rural households, the psychological capital is integrated to extend the sustainable livelihoods framework, the entropy method is used to measure the livelihood capital, and the impact of livelihood capital on relative poverty is analyzed from the dual perspectives of the level and structure of livelihood capital using the data from the China Family Panel Studies(CFPS). The results show that: 1)The level and structure of rural households' livelihood capital are unbalanced. The psychological capital of rural households is the most abundant, followed by human capital, natural capital, social capital and material capital, and the financial capital is the least abundant. The number of psychological capital dominate rural households is the highest. There are small number of rural households dominated by financial capital, material capital and social capital. 2)The higher the levels of human capital, social capital, natural capital, material capital and financial capital are, the smaller the probability of rural households falling into relative poverty is, and the weaker the relative poverty intensity is. 3)Compared with the social capital dominance, human capital domination, natural capital domination, material capital domination, financial capital domination and psychological capital domination have stronger inhibitory effects on relative poverty. Therefore, the level and structure of livelihood capital have an inhibitory effect on the relative poverty of rural households, indicating that livelihood capital is an important factor to prevent rural households from falling into relative poverty.Keywords：livelihood capital level;livelihood capital structure;relative poverty;farmers17|11|4<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：In order to explore the role of digital economy in ecological resources enabling rural common prosperity, based on the spatial heterogeneity, the analytical framework of “ecological resources-digital economy-rural common prosperity” was constructed, and the provincial panel data from 2010 to 2020 were used to conduct an empirical test with the geographic detector tool. The results show that: 1)The value of ecological resources has a driving role in rural common prosperity. Among them, forest resources, grassland resources and natural reserve resources promote the transfer of urban and rural wealth through ecological economization, while government protection and governance investment and sewage reuse ensure the sustainability of sharing the dividends of ecological resource value in rural areas. 2)Digital economy plays a driving role in rural common prosperity. It mainly comes from the fact that digital economy has directly or indirectly promoted the flow of factors from cities to rural areas and alleviated the problem of unbalanced and insufficient development by enabling agricultural production, enriching industrial development models, restructuring the accumulation mode of human capital and promoting the construction of a unified market. 3)The interaction between ecological resources and digital economy has a significant driving effect on rural co prosperity. This mainly comes from the process of defining the property rights of the ecological resources empowered by the digital economy, as well as the process of implementing the property rights such as value accounting, development and construction, market transactions and benefit distribution, to promote the realization of the value of ecological products, so that they can truly become an ecological industry, and thus promote rural common prosperity. Therefore, policy suggestions are put forward in this study from three aspects including promoting rural digital development, building ecological resource supervision, development, trading platform, and promoting the realization of digital economy enabling ecological resource value.Keywords：ecological resources;digital economy;rural common prosperity;geographic detector33|17|5<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
- Abstract：To explore China's agricultural energy efficiency and its evolution trend from the perspective of technological heterogeneity, based on the framework of technological heterogeneity, this study uses the common boundary model to measure China's agricultural energy efficiency in the past 20 years, and uses the standard deviation ellipse analysis, Dagum Gini coefficient, two-way fixed effect and other methods to investigate the spatio-temporal evolution of agricultural energy efficiency and its influencing factors. The results show that: 1)During the sample period, the average agricultural energy efficiency in China is 0. 612, showing an increasing trend year by year, and there is still a large room for improvement. 2)Spatially, the low efficiency is associated with the lack of technological innovation of agricultural machinery equipment and the backward promotion of technology. In terms of time, the ellipse area does not change obviously indicating that the efficiency distribution does not have obvious convergence or divergence trend. 3)Dagum Gini coefficient results show that there is a gap between provinces in agricultural energy efficiency in China, but it tends to narrow, and the regional difference between eastern, central, and western is the main cause of the inter-provincial development imbalance of agricultural energy efficiency in China. 4)Influencing factor analysis shows that agricultural energy efficiency in China is positively correlated with planting structure and infrastructure level, and negatively correlated with energy structure, economic structure and disaster rate. Based on the analysis results, three policy suggestions are proposed in this study to improve agricultural energy efficiency in order to better promote the transformation of China's agricultural green development.Keywords：agricultural energy efficiency;meta-frontier SFA;Dagum Gini coefficient;standard deviation ellipse17|14|1<HTML><L-PDF> <Meta-XML>Updated：2024-07-16
