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- Abstract：The objective of this study was to evaluate the phenotypic characterization and reveal group classification of Tibet maize landraces.One hundred and seventy-nine maize landrace varieties from Tibet were used to carry out phenotypic studies.All materials were planted for a 2-year phenotypic characterization of 36 traits.Shannon-Weaver diversity index was calculated based on the phenotypic estimates.Euclidean distance among the 179 maize landraces was calculated based on phenotypic traits,on which the ward cluster analysis was carried out.The result showed that high level of diversity was observed in the accessions from Tibet maize region.The Shannon-Weaver diversity indices of 20 agronomic traits were more than 2.0 in 36 agronomic traits,among which the especially kernel color reached 2.27 reflecting the characteristics of rich color of accessions from Tibet maize region.The 179 maize landraces were separated into 3 groups by the ward clustering analysis,including late-maturing with high stem genotype,early-maturing genotype from alpine region,hard kernel genotype from dry-hot valley region.The third genotype was the main local germplasm with Tibet characteristics from Tibet maize tradition main plant area.In general,there high level of phenotypic diversity was existed among Tibet maize landrace varieties;Diversity was of great importance in analyzing the ecological evolution,which provides theoretical basis for Tibet as an important afferent path of maize in China.Phenotypic summary statistics revealed that landraces of each group possessed a distinct phenotypic characterization indicating high potential utility of these germplasm in maize breeding and cultivars improvement.Keywords：Tibet maize;landrace;phenotypic diversity;group classification2|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：A total of 18 homologous PIN3 genes were identified in 17 species in Brassicaceae family based on genomic data available including Arabidopsis thaliana,Capsella rubella,Brassica rapa and Brassica oleraceaetc.Gene sequences were subjected to bioinformatics analysis and light-,hormone-response elements and stress-response elements are differently contained in the gene promoter as cis elements.The auxin-response and geotropism response elements are conservative among the 18 homologous genes.The promoter of PIN3 (CbPIN3) from Capsella bursa-pastoris was recombined with GUS reporter system CbPIN3pro::GUS and transformed into Arabidopsis thaliana to investigate the specific expression model of the homologous gene.By comparison of GUS staining,it was found that the CbPIN3 gene displayed same expression pattern with the chip data of PIN3 in Arabidopsis.However,the expression pattern of CbPIN3 varies in some tissue.This might be related to the differentiation of auxin polar transport regulation in plant morphogenesis.The differences in expression pattern of PIN3 between Capsella bursa-pastoris and Arabidopsis thaliana were adaptive evolution in the Brassicaceae family.Keywords：Brassicaceae family;PIN3;gene;promoter elements;expression0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Studies on virus genome variation are necessary for virus disease prediction and control.During 2013-2015,tobacco samples which showed typical vein necrosis symptom were collected from Guizhou Province.Four pairs of specific primers were designed from the conserved regions of published genome sequences of Potato virus Y (PVY).After total RNA extraction,RT-PCR,molecular cloning and sequencing,the data of PVY genome sequence was then used for phylogenetic analysis by MEGA software.The result suggested that two PVY strains,PVY-FQ and PVY-DF,which were collected in tobacco plants from Fuquan area and Dafang area respectively,were confirmed as dominant isolates.Genome sequence analysis showed that PVY-FQ and PVY-DF contained 9 699 and 9 706 nt,of which their unique ORF located in 188-9 373 and 190-9 375 nt respectively.PVY-FQ and PVY-DF were confirmed sharing common genome structure with other isolates published previously.Phylogenetic analysis suggested that PV-FQ had high homology with PVYNTN strain,while PVY-DF had high homology with PVYN strain.Keywords：Potato virus Y;genome sequence;phylogenetic analysis3|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore the effects of sugarcane canopy structures on resistance to pokkah boeng disease.Field experiment was carried out using Fusarium verticillioides as virulent source.Thirteen newly introduced clones from Florida,USA and dominant cultivar ROC22 in Guangxi were taking as planting materials.Principal component analysis and correlation analysis indicated that the pokkah boeng disease resistance was significantly and positively correlated with leaf area of first-top-leaf,and positively correlated with angle index.Furthermore,the 14 tested sugarcane materials were clustered to 4 grades:High resistant varieties (clones) were CP07-2518,CP06-4647,CP06-3458 and CP06-3332;CP07-2547,CP07-1527,ROC22,CP06-3477 and CP06-2897 belonged to resistance grade;CP09-4707,CP09-4369 and CP07-1533 belonged to medium resistance (MR) grade;CP06-3051 and CP06-2422 belonged to medium susceptible (MS) grade.There was correlation between sugarcane canopy structures and pokkah boeng disease resistance.The sugarcane variety (clone) with compact shape,stand upright and narrow leaves,and easy to defoliate displayed stronger resistance to pokkah boeng disease.The sugarcane variety (clone) with loose shape,wide leaves,and uneasy to defoliate showed the weaker resistance to pokkah boeng disease.Keywords：sugarcane;pokkah boeng disease;canopy structures;Fusarium verticillioides0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：A multiplex PCR method was developed for detection of 7 swine respiratory diseases in this study.Based on the conservative sequences of Porcine pseudorabies virus (PRV),Classical swine fever virus (CSFV),Africa swine fever virus (ASFV),Porcine reproductive and respiratory syndrome virus (PRRSV), Haemophilus parasuis (HPS),Pasteurella multocida (PM),and Actinobacillus pleuropneumoniae (APP),7 pairs of specific primers were designed and synthesized.After optimizing the amplification conditions,the results demonstrated that this assay react best at the annealing temperature of 51℃,and the primer concentration of 0.8 μmol/L.The sensitivities of multiplex PCR were 2.59×103,2.56×103,2.52×101,2.49×104,2.46×103,2.43×103 and 2.40×101 copies/μL for PRV,CSFV,ASFV,PRRSV,HPS,PM and APP,respectively.Under the optimized reaction conditions,no cross reaction was detected between these 7 kinds of templates and negative control.Moreover,this assay was also effective in the detection of different serotypes in relevant pathogens.In conclusion,the multiple PCR assay is rapid,sensitive and specific,which can provide scientific basis for clinical differential diagnosis and epidemiologic survey.Keywords：swine;respiratory disease;multiplex PCR;detection method9|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming to study the effect of nitrate on methane yield,rumen fermentation and growth of cattle,in vitro and in vivo experiments were conducted.In vitro experiment was designed by single factor including control,1% and 2% nitrate with 3 replicons.In vivo experiment was conducted on 8 cattle,which was single factor randomized design including no additives and 1% nitrate.The experiment was continued for 56 days,which was 14 d of dietary adaption period,39 d of ad-libitum feeding growth and 3 d of 80% limited feed in chambers.The results showed that the methane productions were respectively decreased by 15.2% and 46.2% under the administrations of 1% and 2% nitrate in in vitro experiment.The methane production was declined by 28.5% in 1% nitrate at 4 h after feeding in in vivo.The reduction of methane/DMI and methane energy/gross energy was respectively 31.8%.Although there were no differences in daily weight gain and feed conversion ratio were not different between treatments and control,nitrate significantly inhibited VFA production.In conclusion,nitrate effectively restrained methane,while had no positive impact on production performance.Keywords：methane;nitrate;cattle;respiratory chambers;growth performance1|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming to find sex-determining genes,transcriptome profile of female and male adults of Parabronema skrjabini in camel were investigated.Samples of female and male were analyzed using Illumina HiSeq2000TM RNA sequencing platform and their transcriptome libraries were constructed.After quality filtering and de novo assembling,functional annotation and bioinformatics analysis were carried out.The results showed that:A total of 6 430 differentially expressed genes between female and male were obtained,of which 2 131 and 4 299 of genes were up-and down-regulated,respectively.And 341 328 and 714 differentially expressed genes were annotated into biological process,cellular component and molecular function and 41 functional categories.KEGG analysis showed that 1 116 differentially expressed genes were assigned to 198 KEGG pathways,and clustered significantly in immuno regulation,oocyte maturation and so on.Functional cluster analysis indicted that reproductive development,oviposition and reproductive behavior were high enriched in female adult stage,whilst the sperm main protein,serine/threonine specific protein phosphorylas etc.were high enriched in male adults stage.Moreover,we identified ten the significant sex-determining genes,such as Tab-3,Tab-5 and Fem-1,eight gender-specific expression genes of male adult and four gender-specific expression genes of female adult.These genes were necessary to decide nematode gender.In this study,the biological characteristics of differentially expressed genes were predicted by bioinformatics,which involved in functional genes and metabolic pathways.This study provides a foundation for the further whole genome sequence analysis,drug target prediction and vaccine candidate gene screening.Keywords：Parabronemas krjabini;transcriptome;differentially expressed genes;bioinformatics analysis0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming at the complication of optimizing water delivery scheduling,and to reflect its spatial and temporal characteristics,a multi-variable and multi-objective optimization model for canal scheduling is proposed,which considers the time uncertainty.Decision variables are flow rates,start time and end time of the distributary canals.The objectives are to minimize the standard deviation of flow rates of superior canal and the seepage of the distributary canals.The model is solved by multi-objective genetic algorithm with the first objective taking the top priority.The results show that:On the premise of satisfying the need of actual operation,compared with planned conditions at the same period,the rotation decreases from 25 to 15 d,the average flow rate of superior canal increases from 1.298 to 1.414 m3/s,the water use efficiency grows from 0.651 to 0.706 and the amount of water into farmland rises by 14.25%.In conclusion,the model can realize concentrated and high-efficient water distribution,and it can be applied to many contexts in order to provide theoretical and technical support.Keywords：canal scheduling;multi-variable;optimization model;multi-objective genetic algorithm2|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In view of the problem that it is difficult to determine whether or not need dredge to govern urban polluted river,indoor research of batch equilibrium static and the Langmuir,Freundlich and Henry model simulation were conducted.And the research materials were sediments from different depths of three typical sections in North Canal,Tongzhou District,Beijing,including Tugou,Yulin Village and Hehe Station were taken as study materials.Thermodynamic behaviors of adsorption and desorption for ammonia nitrogen were studied under eight ammonia nitrogen solution concentration gradients of 20,40,80,160,200,320,400 and 600 mg/L.The results show that:1) Adsorption and desorption processes fitted well with the Langmuir,Freundlich and Henry model with correlation coefficient R2>0.85;2) The sediments' maximum adsorption capacities for ammonia nitrogen of typical sections,whose depth were respectively 0-20,20-40 and 40-60 cm,were 1 184.60-26 168.00,343.46-648.00 and 228.10-462.05 mg/kg. Therefore,0-20 cm sediments' adsorption potential was the biggest.And their maximum desorption capacities were 178.11-367.52,98.45-329.62 and 78.58-148.51 mg/kg,respectively.Thus,the 0-60 cm sediments' desorption potential had little difference;3) The adsorption constants of Langmuir model at different depths in ascending order was kL(0-20 cm),kL(20-40 cm) and kL(40-60 cm).The sort of n,which was adsorption constant of Freundlich model in ascending order was n(0-20 cm),n(20-40 cm)and n(40-60 cm).Above results reflected that the greater the depth of sediment was,the better the adsorption performance was;The desorption ratio of three different depth sediments in ascending order was n(0-20 cm),n(20-40 cm) and n(40-60 cm),which reflected that the greater the depth of sediment was,the bigger the degree of desorption for ammonia nitrogen was;4) About magnitude relation of the ammonia nitrogen mass concentration between sediments' adsorption/desorption critical state and overlying water body,Tugou section's at 0-40 cm depth was greater;Yulin Village and Hehe Station sections' at 0-60 cm depth were less than overlying water body. Dynamic balance for ammonia nitrogen existed in the sediments' adsorption/desorption processes.This study provided theoretical guidance for dredging river management.Keywords：urban river;sediment;ammonia nitrogen;adsorption;desorption;depth of sediment0|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To provide a scientific basis for the rational development and utilization of land resources micro-aggregate and particle-size distribution under different slope lengths and disturbance surface were studied.Through field sampling and laboratory analysis,fractal features of rhizosphere soil micro-aggregate and particle-size and its relationship with soil physicochemical properties in the natural slope and disturbance surface in 20,40 and 60 m were investigated.The results showed that:Soil particle-size distribution in the dominant aggregates was 0.250-0.050 mm,and the content was 33.21%-22.55%;Soil micro-aggregates in the dominant aggregateswere 0.250-0.050 mm and secondary advantage was 0.050-0.010 mm;The fractal dimension under disturbance surface was less than the fractal dimension under natural slope length. The length of slope was longer and the fractal dimension was higher;Soil nutrient content of the longer slope length was higher in the order of 60>40>20 m;Soil nutrients under disturbance surface were less than those under natural slope length in three slope lengths;Positive correlation between soil fractal dimension with the soil bulk density was significant (P<0.01) while soil total nutrient was significantly associated (P<0.01) and the dimension of soil fractal under disturbance surface with soil porosity were significant or very significantly correlated (P<0.01 or P<0.05).In conclusion,the fractal dimension of soil micro-aggregate and particle-size distribution better reflected physical and chemical structure of soil in the purple soil area and more intuitively reflected the changing of soil structure and physical and chemical properties after the disturbance,which providing a scientific basis for soil quality evaluation and agricultural assessment in purple soil area.Keywords：slope length;disturbance surface;soil micro-aggregate;soil physicochemical properties;fractal features0|7|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to improve the quality of whole straw coverage with no tillage planter and reduce the throwing power consumption.Box-Benhnken central composite experimental design principle was adopted to study the working parameters of impeller-blower.Rotating speed,material moisture,vane slope angle were taken as three factors. Experiments on the three factors with three levels of response surface were conducted.A mathematical model of response surface was established.The influence of each factor on the working quality and optimize each factor comprehensively was analyzed.The results showed that the rotating speed,material moisture,vane slope angle in a decreasing order reduced power consumption significantly.The best model for comprehensive work parameters was set as following:when the rotating speed was 1 600 r/min,the material moisture was 63% and vane slope angle was 9°,the specific power consumption was 919.89 m2/s2.Through comparing the mathematical model with the experimental result,it was discovered that the relative errors of all the property indices between these two were less than 5% indicating the model established was useful and could be used for predicting and optimizing.Keywords：no tillage planter;impeller-blower;mathematical model;response surface methodology;optimization2|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming at the problems of low efficiency,high energy consumption and repeatedly rubbing of the buckwheat huller,the main working parts of the huller were improved and the causes of the error of gap adjustment were analyzed.Research on improving the milled rice rate and reducing the relative broken rice rate during the shelling were conducted.Buckwheat's particles size between 4.6 and 4.8 mm were selected as test material and the milled rice rate and relative broken rice rate were taken as evaluation index.Main factors affecting shelling efficiency were shelling gap,running speed of sand disk and gap circumferential error.The results showed that:When the shelling gap was nearly 5 mm,the milled rice rate was higher and relative broken rice rate was lower;With the increasing of sand-disc speed,the relative broken rice rate was quadratic function gradually ascending,the best speed was 950 r/min.Orthogonal experiment results showed that:The clearance of shelling circumferential error significantly affected the relative rate of broken rice;The peeling clearance and speed of sand wheel affected the rice yield rate and reduced the relative rate of broken rice.In conclusion,when the shelling gap was 4.8 mm,the running speed of sand-disc was 950 r/min and circumferential gap to the error was less than or equal to 0.05 mm,the milled rice rate reached 35.4%,the relative broken rice rate was 5.8%,and the milled rice rate was higher than the current level of production of buckwheat rice by 10%-25%.0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Leakage,vibration and noise problems often happen in the existing hydraulic system piping structure of spraying seeding-machine.Hydraulic manifold block (HMB) was adopted in the machine and fluent software was used to perform the numerical simulation analysis of channel flow field.The results showed that:1) HMB effectively reduced the existing hydraulic system piping structure,which made the hydraulic system compact and achieved no-pipe connection between components.Meanwhile it reduced leakage,vibration and noise;2) The pressure loss was related with the HMB structure and fluid velocity.By analyzing of the impact of internal structure to field influences,under operating conditions permitting,it reduced the velocity of the fluid in order to reduce the pressure loss;3) By optimizing the channel structure,the pressure loss was reduced.Increasing technical hole in the "T" type channel,the pressure loss can be reduced by about 8%.When the inlet and outlet port diameter were inconsistent,the outlet port diameter of 0.8 to 1.2 times the inlet diameter was recommended.Keywords：spraying seeding-machine;hydraulic manifold block;flow field;pressure loss;channel structure0|9|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To realize timely and accurately diagnose and identification of alfalfa leaf diseases,automatic recognition of four kinds of alfalfa leaf diseases including common leaf spot caused by Pseudopeziza medicaginis,rust caused by Uromyces striatus,Leptosphaerulina leaf spot caused by Leptosphaerulina briosiana and Cercospora leaf spot caused by Cercospora medicaginis,was investigated based on image processing technology.A sub-image with one typical lesion or multiple typical lesions was obtained by artificial cutting from each of 899 digital images of the four kinds of alfalfa leaf diseases and then was segmented by using a segmentation method integrating with K median clustering algorithm and linear discriminant analysis.After segmentation,a total of 1 651 typical lesion images,each of which only contained one lesion,were obtained for further feature extraction and image recognition of the diseases.Features of the typical lesion images were extracted based on convolutional neural networks and were then used to build support vector machine (SVM) models for image recognition of the diseases.The results showed that the optimal one among the SVM models was built based on the normalized feature HSV,were obtained by merging the normalized features H,S and V while the corresponding original features which was extracted from the normalized lesion images of 32×32 pixels.For this optimal disease recognition SVM model,the recognition accuracy of the training set reached 94.91% and that of the testing set was 87.48%.The results indicated that the image recognition model built based on deep learning and SVM could be applied to conduct the recognition and identification of the four kinds of alfalfa leaf diseases.In this study,some basis and methodological references were provided for the diagnosis and identification of alfalfa diseases and other plant diseases.Keywords：alfalfa;disease;image recognition;feature extraction;deep learning;convolutional neural network;support vector machine11|9|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to research the characteristics of bacterial community in aquaculture water,a tracking simulation experiment was carried out to monitor the cyanobacterial bloom process in the aquaculture base of Pearl River Fisheries Research Institute from May to July in 2015.The bacterial community composition in the water during this process of cyanobacterial blooms outbreak was analyzed by high-throughput sequencing technology.The result showed that the percentage of Bacteroides increased along with the escalation of the cyanobacteria bloom and declined when the bloom diminished;On the contrary,the percentage of Actinobacteria declined constantly throughout the bloom process;at the end stage of the bloom,dissolved oxygen was almost depleted in the water,and the anaerobic Heliobacteria,which belong to the Firmicutes,thus gained a high percentage in the overall bacterial population as the cyanobacterial bloom faded away.The bacterial diversity in the water decreased with intensifying bloom and recovered as the bloom faded away.This study not only provided bacterial diversity information of bacterial community,but also supplied information in the water throughout the cyanobacterial bloom occurrence process.Keywords：aquaculture water;cyanobacterial bloom;high-throughput sequencing;Bacteroides;Actinobacteria;Firmicutes;bacterial community0|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore the sustainable utilization of reclaimed land and industrial transformation in coal mining area,the mechanism and mode of reclaimed land and industrial transformation were studied through the composition relationship analysis of the industrial structure framework.The traditional land reclamation mode and the industrial structure characteristics and succession regulations in the mining area were also investigated by taking the industrial chain extension of Pingshuo mining area as an example.The conclusions are that the sustainable use of reclaimed land and the target mechanism of industrial transformation in China's mining area should be transformed to "multiple coexistence of leading mechanism" from "dual leading mechanism",and finally achieve "multi-party cooperation leading mechanism".Change of the industrial framework from extensive and epitaxial type to lean and connotative type is an inevitable requirement in Pingshuo mining area to enhance its core competitiveness.According to the different industrial chain,Pingshuo mining industry transformation modes have two categories.One is black industrial chain:"coal mining-coal gangue-electricity-silica-alumina-building material industry",which can realize the efficient use of resources,energy and waste,and reduce the environmental pressure of industrial transformation.The other is green ecological industry chain:"agriculture-forest-animal husbandry-medicine-agricultural product processing-ecotourism",which is an inevitable way to reconstruct the space of "production,life and ecology" and promote the function of land reclamation on the basis of the economic and technical principles of the rural complex.Keywords：mining area;land reclamation;industrial transformation;industrial chain extension;Pingshuo mining area0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to quantitatively evaluate landscape ecological effects before and after land consolidation,a land consolidation landscape ecological effects evaluation system,which contains four levels and fourteen indexes,is constructed.Comprehensively landscape and ecology effects are considered and relevant theories of landscape ecology are applied.AHP is used to determine index weight and apply comparative analysis method to determine indicators division level and scores.The evaluation system is applied to evaluate the landscape ecological effect of a land consolidation project,which is located at Hanshan Country,Anhui Province.The results show that contribution rate of comprehensive landscape ecological effects is 13.86% in the land consolidation project,which plays a certain improvement role in regional ecological environment and landscape functional although there is also a large room for improvement.Keywords：land consolidation;landscape ecological effects;ecological effects;landscape effects;analytic hierarchy process0|9|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to promote social investors' enthusiasm in land consolidation-PPP model,this paper analyzed the features of game behavior in the mode between local governments and social investors are analyzed.An Evolutionary Game model is established to analyze the game behavior features of local governments and social investors' evolution paths in land consolidation-PPP Mode,and to study a land consolidation project of B Street in Nanjing.If social investors' expected revenue is less than their opportunity cost,local governments' fostering will stimulate investors' motivation to take part in the PPP project.It is found that,the revenue,which is brought to local government and social investors,increases continuously by the project.The optimal strategy for governments is to help social investors' to engaging in the PPP project,and for investors to join it actively.In the land consolidation project of B Street,when social investors' expected revenue is more than their opportunity cost,all of them steadily tend to engage the project.The support for social investors depends on local governments' income.When the income decreases,the support will fall.Two suggestions are put forwarded to further promote social investors' positivity in the mode,and speed up construction of land consolidation-PPP Mode market:One is to set up an incentive mechanism of land consolidation PPP project to complete local governments' performance appraisal mechanism.The other is to establish reverse constraint mechanism of the land consolidation PPP project.Keywords：land consolidation and readjustment;public-private partnerships;evolutionary game theory;project financing land credit2|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the micro survey data,the Probit-ISM model is used to determine factors influence the willingness of farmers to participate in land trust circulation.The results show that income structure and the trust degree on local government are direct surface factors.And the income of non-agricultural employment and local economic development level are intermediate reason.Householder age,whether or not they participate non-agricultural employment and in employment stability are both the deep root of factors.Further analysis showed that improving the stability of employment was the key factor for land trust circulation.Keywords：land trust;farmers’ willingness;participation behavior;influencing factors;Probit-ISM model0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To acquire an accurate understanding the spatial distribution rule of agricultural non-point source pollution in China,the panel data of 30 provinces in China from 1997 to 2013 were adopted to analyze the spatial and temporal distribution characteristics of Chinese agricultural non-point source pollution. A non-parametric kernel density estimation model was built to discuss the dynamic evolution of agricultural non-point source pollution and an exploratory spatial data analysis method was further employed to discuss its spatial correlation.The result showed that:Pollution from four sources including agricultural fertilizer inputs,agricultural solid wastes (straws),aquaculture and livestock and poultry farming,and three kinds of pollutants,which are nitrogen,phosphorus and chemical oxygen demand,kept increasing year by year.Among which,the livestock and poultry breeding contributed the most.The area of serious agricultural non-point source pollution was concentrated in big agricultural provinces and economically developed places.The central and northern regions were the core area in the spatial distribution,and the core area was radiating to the external and shows a decreasing trend.Agricultural non-point source pollution areas agglomerated obviously,but differed greatly,and polarized seriously.Agricultural non-point source pollution showed obvious spatial correlation,and formed a high-high concentration area,mainly located in big agricultural provinces.Therefore,the policy incentives should be strengthened,environmental awareness of farmers should be guided,and agricultural production should be encouraged to develop from extensive growth to quantity and qualitative and quantitative growth.Considering the negative effects of spatial spillovers of adjacent regional policy,the zone defense policy should be utilized to eliminate the shift of agricultural non-point source pollution management in high-high agglomeration areas and to create a win-win situation with great effort and strict control.Keywords：agricultural non-point source pollution;spatial correlation;dynamic evolution;spatial differentiation0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore key factor substitution and growth path of citrus production based on the panel date on the cost-benefit of citrus from 1997 to 2014 in seven main production areas in China.An empirical analysis of the substitution relationship among the citrus production factors to investigate the technical progress and growth path of citrus production in China was conducted by using transcendental logarithmic production function.The results showed that:The output elasticity of labor force and agricultural machinery was relatively stable,and the output elasticity of chemical fertilizer and other factors was fluctuant;The substitution relationships of chemical fertilizer to labor,agricultural machinery to labor,and other factors to labor force were significant,The substitution relationships of chemical fertilizer and agricultural machinery to other factors were stable;There also existed a complementary relationship between fertilizer and agricultural machinery factors;In the process of citrus production,the labor-saving technical progress was obvious,and the land-saving technical progress is developing constantly.The future growth path of citrus production should be mainly in the direction of labor-saving agricultural machinery technology and aided in the direction of land-saving biochemical technology.In conclusion,the choice of the development direction of citrus technical progress should be made bases on its endowment advantage of production factors;Focuses should be on the development of labor-saving citrus production machinery technology and reasonable application of the land-saving biochemical technology including chemical fertilizer,pesticide,plastic film,and free-virus seedling wood.Keywords：factor substitution;growth path;transcendental logarithmic production function;random effect model;citrus fruits7|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：From the perspective of key factor marketization level,the impact and mechanism of financial (capital),labor and land market level to the income gap between urban and rural residents were explored based on 1999-2013 national 30 provinces (municipalities and autonomous regions) panel data.The results showed:1) With the upgrading of the level of financial market nationally,the income gap between urban and rural areas gradually expanded,and the level of labor market had no significant influence on the income gap between urban and rural areas,while land market was conducive to narrow the income gap;2) Two periods,1999-2007 and 2008-2013,the results of eastern and central-western areas regional analysis both showed that the three elements had different impacts;3) Mechanism analysis discovered that finance and labor market can effectively improve the income of urban residents,and finance and land market can effectively improve the income of rural residents.Based on the above research,several specific policy recommendations are put forwarded.Keywords：market-oriented level of elements;urban-rural income gap;finance;labor;land0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：PMP model is used to analysis the effect of the subsidy policy on alfalfa planting farmers in Huanghua City,Hebei Province based on the survey data.The results show that the implementation of direct subsidies to alfalfa growers does not change the production structure of the farmers;while the subsidies linked acreage can effectively enhance the enthusiasm of farmers planting alfalfa and significantly increase the economic efficiency of farmers.The results also show that alfalfa product prices and grain price fluctuations affect the effect of subsidies.Grain prices affect the effect of subsidies on alfalfa planting area expanded in the opposite direction and affects farmers' income in the same direction.Alfalfa price affects the effect of subsidies in the same direction in these two areas.According to the measurement results,we suggest that:The development of the government subsidy policy should distinguish between professional and non-professional alfalfa planting area;Alfalfa subsidies should change with external conditions and make timely adjustments;Alfalfa subsidies must consider factors which can change the alfalfa planting acreage,and guarantee alfalfa growers having stable income.Keywords：alfalfa;PMP model;farmers subsidies;effect0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming at the problem of risk assessment for seed enterprises by combining the seed enterprises' risk and seed enterprises characteristics,an evaluation model on the risk of the seed enterprise is built.An optimum index set of influence factors on the risk of the seed enterprise is chosen.Synthetic evaluation for rule layer is made and an evaluation matrix is then built with determining the weight of index layer through evaluation matrix and AHP method.Three representative seed enterprises,which are Beijing Doneed Seed Company,Origin Agritech Limited and China National Seed Group Company,are selected to analyses empirically.Their scores of synthetic evaluation of risk are 0.56,0.58 and 0.67 respectively,and their risk ranks in descend order is G1,G2 and G3.In conclusion,China National Seed Group Company does best in risk management among the three enterprises and there is apparently much room for improvement in Beijing Doneed Seed Company.Keywords：risk of seed industry enterprise;risk assessment and risk management;information entropy;AHP method;risk ranking0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
