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- Abstract：In order to clarify the characteristics of kernel growth and development between different positions of maize ear under synchronous pollination (SP) and natural pollination (NP) treatments,the maize hybrid ‘Zhengdan 958’ was grown in the field at two planting densities (5 and 11 plant/m2).The results showed that:The SP respectively increased kernel number by 1.1% and 30.0% at 5 plants/m2 and 11 plants/m2 in 2017; 1.4% and 26.2% at 5 and 11 plants/m2 in 2018.The ovary/kernel weight at apical region of ear was significantly lower than that at the basal region of ear during early kernel development under NP treatment.Difference between apical ovary and basal ovary turned smaller from silking to pollination day and no difference was found at pollination day under SP treatment;The ear growth rate was significantly increased at 15 d (days after pollination) by SP.Hence,the effect of SP on grain number per ear was not significant under low plant density.However,the grain number per ear and ear growth rate were significantly increased under high plant density indicating the decrease of the difference between the apical and basal ovary and grain growth,and the enhancement of assimilate distribution to sink.Keywords：maize;kernel number;synchronous pollination;natural pollination;ovary;sink1|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore suitable cultivars and planting density for maize in south of Shanxi Province.Effects of planting density on the stalk characteristics and yield of summer maize cultivar ‘Xianyu 335’,‘Zhengdan 958’ and ‘Xundan 20’ were investigated.The experiment involving 7 planting densities (4.50×104,5.25×104,6.00×104,6.75×104,7.50×104,8.25×104 and 9.0×104 plant/hm2) of maize were conducted.The results showed that:Plant height and ear height increased with the increase of planting density,while the stem diameter decreased and lodging rate increased;Under the same density condition,the lodging rate of ‘Zhengdan 958’ is lower than that of ‘Xianyu 335’ and ‘Xundan 20’.The maximize yield of ‘Xianyu 335’,‘Zhengdan 958’ and ‘Xundan 20’ were 11 034、8 668 and 8 456 kg/hm2 when the planting densities were 7.50×104,8.25×104 and 9.00×104 plant/hm2,respectively.With the increase of planting density,the number of ears per unit area increased,while ear length,ear diameter,kernels per row and 100-kenel weight decreased.According to the results of comprehensive traits of stem and yield,the planting density of ‘Xianyu 335’ with the planting density ranged from 6.75 to 8.25×104 plant/hm2 is preferable for maize production.1|9|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The impacts of change in three climatic factors,cultivar and other agronomic management practices change on growth duration of winter wheat and summer maize in Henan Province were analyzed based on crop phenology data from 30 winter wheat and 18 summer maize agro-meteorological observational stations during 1980-2014.The first difference and stepwise regression methods were adopted in this study.The results showed that 1) The reviving date of winter wheat was delayed during 1980-2014,while the jointing,heading and maturity dates were advanced.The growing periods from the reviving to jointing and from the jointing to heading were shortened by 4.8±1.9 and 3.3±0.9 d/10 a respectively.The growing period from the heading to maturity was prolonged by 2.3±0.8 d/10 a.The whole growth duration of winter wheat did not change significantly in most stations of Henan Province.There was also no significant change in phenological phases of summer maize in a majority of agro-meteorological observation stations.The whole growth duration of summer maize was prolonged at 44% of the stations.The growing period from tasseling to maturity was prolonged by 2.5±1.4 d/10 a.2) The temperature increased in winter wheat growing season during 1980-2014.Precipitation decreased at 33% of the study stations.Moreover,there was no significant change in winter wheat growing season average daily solar radiation.During the growing period from reviving to jointing,the mean temperature and averaged daily solar radiation increased,while precipitation in the growing period decreased.During summer maize growing season,the mean temperature increased at 39% of the study stations.However,the growing season averaged daily solar radiation decreased at 39% of study stations.There was no significant change trend in growing season precipitation.During the growing period from the emergence to jointing,mean temperature increased.However,the averaged daily solar radiation during the growing period from the emergence to jointing and from the heading to maturity decreased.3) The length of growth duration of winter wheat was sensitive to changes in temperature,precipitation and solar radiation.The length of growth duration of summer maize was sensitive to changes in temperature and solar radiation.In general,changes of temperature,precipitation and averaged daily solar radiation shortened the whole growth duration of winter wheat and summer maize by 6.3±4.2 and 0.8±0.9 d/10 a,respectively.Cultivar shifts and change in agronomic management practices prolonged the whole growth duration of winter wheat and summer maize by 5.2±5.4 and 2.6±2.6 d/10 a.The results revealed that climatic factors change shortened growth duration of both winter wheat and summer maize.However,cultivar shifts and change in agronomic management practices compensated the negative effect induced by climate change.There was uncertainty in the impacts of climatic factors,cultivar shifts and change in agronomic management practices on the growing periods of winter wheat and summer maize in Henan Province.The study provides an important reference in adapting to climate change and arranging crop growth season rationally.Keywords：winter wheat;growing season;climatic factors;variety;summer maize;Henan Province1|9|6<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The aims of this study were to investigate the nitrogen,phosphorces,potassium rates and fertilizer formulates and provide references for optimal and scientific feritilization in diffirent wheat production regions.Unreasonable formulae and application of fertilizer has been the main factors to limit wheat production.This study first summarized and analyzed a total of 1 575,4 232 and 3 924 on-farm experiments with various rates of nitrogen (N),phosphorus (P) and potassium (K),and then conducted during 2005-2010 across major agro-ecological regions of wheat production in China.Based on the data and literature analysis,China wheat production area were divided into 7 sub-regions of fertilization.The optimal rates of N,P and K were then estimated and formulated optimized compound fertilizer in each sub-region.The results showed that:Wheat yield was highest in the North China Plain (Ⅲ),6.8-7.5 t/hm2,followed by the irrigated sub-region in the Northwest China (Ⅱ-2) and the middle and lower reaches of Yangtze River (region Ⅳ) 6.0 t/hm2,others were the lowest on average 5.3 t/hm2.In the nationwide,the optimal rates of N across all the 7 sub-regions were N 169 kg/hm2 on average and ranged from N 106 kg/hm2 in the Northeast China (Ⅰ) to N 184 kg/hm2 in the irrigated sub-region in the North China Plain (Ⅲ-1).The optimal rates of P were P2O5 77 kg/hm2 on average and ranged from P2O5 55 kg/hm2 in the southwest region (Ⅴ) to P2O5 88 kg/hm2 in the irrigated sub-region in the North China Plain (Ⅲ-1).The optimal rates of K were K2O 50 kg/hm2 on average and ranged from K2O 36 kg/hm2 in the rain-fed sub-region in the Northwest China (Ⅱ-1) to K2O 59 kg/hm2 in the rain-fed sub-region in the North China Plain (Ⅲ-2).Given variation in the optimal nutrient rates,climate,crop production and soil types among different agro-ecological regions,a total of 9 regional special fertilizer formulaes were designed for the 7 wheat sub-regions in China,including 7 formulae using a basal plus top-dressing fertilization approach and 2 formulae using only basal fertilization application.Keywords：wheat;region;sub-region of fertilization;optimal nutrient rate;fertilizer formula6|11|13<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore the influence of lower irrigation limit and emitter flow on winter wheat growth under subsurface drip irrigation,a full factor experiment was conducted with 3 emitter flow types (0.1,0.9 and 1.5 L/h) and 2 lower irrigation limits (80% and 60% of field capacity in the test site).The effects of different experimental treatments on soil moisture distribution and winter wheat growth were analyzed.The results showed that:The higher flow subsurface drip irrigation had a large amount of water infiltration,which resulted in an increase in soil moisture content in 40-80 cm soil layer.The smaller flow subsurface drip irrigation water was mainly stored in the upper soil.The lower limit irrigation of 80% field capacity,compared with 60% field capacity,promoted the increase of plant height,leaf area index,dry matter accumulation and yield of winter wheat,and reduced the decrease of flag leaf Chlorophyll content during grain filling period.The leaf area index of winter wheat treated with 0.9 L/h under different flow treatments was the highest.Increasing the emitter flow rate could reduce the lowering of the Chlorophyll content under the lower irrigation limit of the 60% field capacity.Considering crop growth,yield and water use efficiency comprehensively,the optimal irrigation system under the conditions of this experiment is the lower limit irrigation of 80% field capacity and irrigation water flow rate of 0.9 L/h.Keywords：winter wheat;subsurface drip irrigation;soil moisture;plant growth0|9|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The multi-spectral image of winter wheat obtained by UAV is used as the data source,and the traditional vegetation index is improved by making full use of the red edge channel unique to multi-spectral sensors.The LAI of winter wheat is then carried out for inversion accuracy comparison based on the method of modeling multiple vegetation indices.The results show that the random forest (RF) based on multi-vegetation index is more accurate than the Akachi information criterion-partial least squares method (AIC-PLS).R2=0.822,and RMSE=1.218 are obtained between the obtained LAI inversion value and the true value.The study proves that the random forest prediction has a better fitting effect and has a good applicability to the LAI inversion of winter wheat.Keywords：UAV;multi-spectral remote sensing;LAI;inversion;AIC-PLS;random forest5|10|18<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore cotton cytoplasmic male sterility (CMS) genes,the mitochondrial differential genes and their expression levels between CMS line ‘07-113A’ and its maintainer line ‘07-113B’ were compared by RFLP,Northern blot,homologous cloning and Real-time quantitative PCR(RT-qPCR) analyses.The results showed that:1) A total of twelve mitochondrial genes were used as probes and digested with EcoR Ⅰ and Hind Ⅲ restriction endonuclease in RFLP analysis.Among which,only atpA/EcoR Ⅰ and ccmB/EcoR Ⅰ combinations displayed polymorphism;2) The Northern blot analysis of atpA and ccmB genes revealed same transcript size between the two lines;3) The CDS sequence of atpA and its partial flanking sequences were cloned from the CMS line and its maintainer line.The results indicated that there was no difference between the sterile line and the maintainer line in the coding sequences,while there were 2 bp variations at the 5' flanking sequence and 4 bp variation at the 3' flanking sequence of the sterile line compared with the maintainer line.4) RT-qPCR analysis showed that the expression of the atpA in the CMS line was 0.44,relatively to the control ‘07-113B’ (P<0.01).It is speculated that CMS line (‘07-113A’) pollen abortion may be associated with abnormal expression of atpA.Keywords：cotton;cytoplasmic male sterility;RFLP;atpA;gene expression0|9|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To clarify the expression pattern of cucurbitacin glycoside catalyzed by Citrullus colocynthis L.Shrad UDP-glycosyl transferase.The C.colocynthis L.Shrad "WM9" variety leaves were used as the test materials.The C.colocynthis L.Shrad UDP-glycosyl transferase gene was cloned by RT-PCR and the physicochemical properties of the encoded proteins were analyzed.The expression patterns of two C.colocynthis L.Shrad UDP-glycosyl transferase genes in different tissues and organs were investigated by qRT-PCR and ACTIN as the internal reference gene.The results showed that:Two UDP-glycosyl transferase genes UDP-E1 and UDP-E2 with full-length cDNA sequences of 1 546 bp and 1 559 bp were obtained,named.The results of biological information analyses determined that the complete open reading frame (ORF) of the UDP-E1 gene is 1 314 bp in length encoding 437 amino acids,and its theoretical molecular weight is 49.02 ku.The isoelectric point was 5.99 and is a stable protein.Genbank accession number is MK576125.The UDP-E2 gene has an ORF of 846 bp and encodes 281 amino acids with a theoretical molecular weight of 32.78 ku and an isoelectric point of 5.23.It is an unstable protein and Genbank accession number is MK576126.These two genes belong to the glycosyl transferase superfamily.Sequence multiplex alignment and phylogenetic tree analysis showed that the genes UDP-E1 and UDP-E2 have the highest similarity to the UDP-glycosyl transferase gene sequences of melon and cucumber.UDP-glycosyl transferase was expressed in all tissues and organs,and the expression level was the lowest in stems and the highest in leaves.The expression level was the lowest in stems and the highest in leaves.0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Morphological character analysis and SRAP molecular marker analysis were used to study the genetic diversity of seven new Phalaenopsis varieties and three lines,which were selected and bred from the progenies of Phalaenopsis ‘Jubao Red Rose’ and Phalaenopsis ‘Ben Yu Star’ by Environmental Horticulture Research Institute of Guangdong Academy of Agricultural Sciences.The results of morphological character analysis showed that the offspring had obvious diploid maternal inheritance,low degree of genetic variation and almost no superparental inheritance.On the other hand,a total of 24 primer pairs with stable bands and good polymorphism were screened.A total of 172 bands were amplified with an average of 7.17 fragments,up to 10,and at least 4 per pair of primer among which 99 (58.14%) were polymorphic bands.Based on the amplification results of SRAP markers,the genetic similarity coefficients of GS were calculated by using NTSYS 2.10e software,and a UPGMA clustering map was established.At the genetic distance of 0.778,the parents and offspring could be divided into 4 subgroups,which were closely in line according to the morphological characteristics.The results of morphological character analysis and molecular markers showed that the genetic differentiation of offspring was small due to the high degree of parental similarity,which was not conducive to the breeding of new varieties.Keywords：new variety breeding;hybrids;morphological character;SRAP1|9|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to rationally utilize and protect the natural enemies in tea garden and provide scientific basis for integrated pest control,a comparative study on the close degree of spatial follow-up relationship between Brevipalpus obovatus Donnadieu,Monolepta hieroglyphica mots and natural enemies of "Baihaozao" tea garden in 2015 and 2016 was conducted.Using the geostatistical method to obtain the variances of the semivariogram theoretical model,the gray correlation degree between the nine natural enemies and the two pests was studied by the grey correlation analysis method.And the parameter was then divided by the maximum value of this type of parameter,and its quotient was a close index.The larger the closeness index value was,the closer the spatial follow-up relationship between natural enemies and pests was,and the higher the predatory parasitism rate to pests was.According to the results obtained above,the degree of closeness of natural enemies to the spatial follow-up relationship of the two pests was judged.In 2015,the top five natural enemies closely related to Brevipalpus obovatus were Clubiona japonicola Boes (1.000 0),Leis axyridis Pallas (0.979 0),Neoscona theisi Walckenaer (0.954 9),Tetragnatha squamata Karsch (0.943 9) and Theridion octomaculatum Boes.et Str.(0.934 6).In 2016,the top five natural enemies closely related to Brevipalpus obovatus were Theridion octomaculatum (1.000 0),Erigonidium graminicolum Sundevall (0.977 8),Misumenops tricuspidatus Fabr. (0.970 6),Clubiona japonicola (0.958 6) and Leis axyridis (0.897 4).Compared with the sum of the two years' close index,the top five natural enemies were Clubiona japonicola (1.958 6),Theridion octomaculatum (1.934 6),Leis axyridis Pallas (1.876 4), Erigonidium graminicolum (1.870 2) and Misumenops tricuspidatus (1.793 7) in turn.In 2015,the top five natural enemies closely related to Monolepta hieroglypica were Tetragnatha maxillosa Thoren (1.000 0),Clubiona japonicola (0.966 3),Neoscona theisi (0.955 1),Erigonidium graminicolum (0.928 3) and Misumenops tricuspidatus (0.928 8).In 2016,the top five natural enemies closely related to Monolepta hieroglypica were Misumenops tricuspidatus (1.000 0),Clubiona japonicola (0.999 1),Erigonidium graminicolum (0.988 8),Theridion octomaculatum (0.975 2) and Tetragnatha maxillosa (0.950 9).Compared with the sum of the two years' close index,the top five natural enemies were Clubiona japonicola (1.965 4),Tetragnatha maxillosa (1.950 9),Misumenops tricuspidatus (1.928 8),Erigonidium graminicolum (1.917 1) and Leis axyridis (1.841 4) in turn.The Clubiona japonicola was the first natural enemy closely related to the two pests' space.On April 11,2015,the ratio of the number of individuals of Brevipalpus obovatus to the number of individuals of the first natural enemy Clubiona japonicola closely related to space was 65.25,and the ratio to the number of individuals of the ninth natural enemy Neoscona theisi was 130.50.On April 11 2016,the ratio of the number of individuals of Monolepta hieroglypica to the number of individuals of its first natural enemy Misumenops tricuspidatus was 1.322 0,and the ratio of the number of individuals of its ninth natural enemy was 4.105 3.Preliminary analysis showed that the smaller the ratio of pests to natural enemies was,the closer the spatial follow-up relationship between natural enemies and target pests was.The shortage of bait was the cause of the close spatial follow-up relationship between pests and their natural enemy insects.This method was an ideal analysis method to judge the spatial follow-up relationship between pests and their natural enemy insects.Keywords：Brevipalpus obovatus;Monolepta hieroglyphica;geostatistics;grey correlation;spatial following relationship1|8|7<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to address the question of construct the rodent lepidic predominant adenocarcinomas (LPA) model,literatures related to LPA using Jaagsiekte sheep retrovirus (JSRV) were searched by using "JSRV","adenococinomas" and "mouse model" as keywords.The related literatures were reviewed and summarized.The results showed that:Numerous studies demonstrated that JSRV-mediated rodent cell transformation mainly depended on non-receptor-dependent mechanisms,through PI3K/Akt and Ras/MEK/MAPK signaling pathways.The main construction method was transfecting plasmid into cells or to breed transgenic animals.The rodent LPA model constructed using JSRV based on complete bioinformatics data was optimal model for further study of the pathogenic mechanism of LPA molecules.However,the pathogenesis of LPA and the targeted drug for different stages of LPA need further studies.Keywords：Jaagsiekte sheep retrovirus;lepidic predominant adenocarcinomas;tumor model;signaling pathway;tumorigenic mechanism0|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To identify high efficient cellulose degrading bacteria from faeces of yak and promote high fiber feed utilization in Tianzhu Country,Gansu Province,high-yielding cellulase strains were isolated from the feces of yak firstly by the methods of Congo red staining method and then by cellulase activity analysis.Morphological observation,physiological and biochemical characterizations and the analysis of 16S rDNA sequences alignment were conducted for further identification.The culture time,culture temperature,initial pH and inoculation size were optimized by single factor analyses and Box-Behnken design was then adopted on the basis of optimization.Wheat,corn and rice straws were treated with optimized cellulase solution,and the degradation rate of straws was measured 10 days after treatment.The results showed that a high-yielding cellulase strain M2 was isolated and identified as Bacillus pumilus.The optimum conditions for M2 to produce cellulase were shown as follows:Culture temperature 33℃,initial pH 6.5,inoculum size 5% and culture time 30 h.Under the optimum condition,its CMCase activity reached 520 U/mL,which was 1.3 times higher than before and the FPAse activity was up to 98 U/mL,which was 1.1 times higher than before.The degradation rate for corn straw was better than the other two types of straws.The degradation rates of cellulose,hemicellulose and lignin of corn stalk were 36.2%,25.5% and 4.3%,respectively.Keywords：Yak;cellulase;faeces;Bacillus pumilus;enzyme optimization;straw degradation2|11|6<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To understand the situation of the resistance in gastroinstestinal nematodes of grazing sheep to current anthelmintics (ivermectin and albendazole),an investigation was carried out by taking 60 grazing sheep infected with gastroinstestinal nematodes in Helinger,Hohhot and Salaqi,Baotou as study objects.The grazing sheep were randomly divided into 3 groups with 20 in each group.Two experimental groups were respectively treated with ivermectin or albendazole,while the control group received no treatment.Faecal egg count reduction tests were employed to determine the efficacy of the these two drugs against gastroinstestinal nematodes infection.The results showed that the reduction in arithmetic mean faecal egg counts achieved by ivermectin or albendazole in Helinger were 28% and 77% after 72 h of treatment,respectively,and their effects were respectively 40% and 100% in Salaqi.This study indicated that there was high resistace of ivermectin against the gastrointestinal nematodes in grazing sheep in two areas and there were mildly resistance of albendazole in Helinger.However,albendazole appeared to be very effective on sheep in Salaqi.Keywords：sheep;Inner Mongolia;Ivermectin;albendazole;gastrointestinal nematodes;drug resistance0|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming at the problems in traditional egg hen behavior detection,single classification and poor real-time performance in laying hens,a lightweight hen behavior detection algorithm TD-YOLOV3 based on deep learning was proposed.The detection algorithm uses YOLOV3 as the basis network structure and compresses the network structure to obtain a lightweight T-YOLOV3 network structure to improve the system detection speed;The residual module in the first multi-scale prediction was replaced with Dense block and add the MLP in the NIN network after the convolutional layer of the Convolution 5,Convolution 7,Convolution 10 and Convolution 13 in the network structure to improve detection accuracy;The data set of this study was trained and tested by clustering dimension optimization and training strategy optimization based on K-means algorithm.The test results showed that the average precision of the TD-YOLOV3 detection algorithm proposed in this study was 89.26%,the detection speed was 33 frames per second,and the parameter quantity was 55 MB.Compared with YOLOV3 and T-YOLOV3 at the same hardware level,TD-YOLOV3 has the best overall performance in terms of detection speed and accuracy,and is more suitable for real-time automatic detection of cage laying behavior.Keywords：laying hens;YOLOv3;Dense block;K-means algorithm8|9|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Traditional meat freshness detection methods need longer time and complex procedure to get the results.In this study,the spectral reflectance data of pork were collected under normal temperature conditions in the laboratory,and the spectral detection methods of meat freshness were investigated.The effects of different modelling methods and sampling intervals on prediction accuracy were also analyzed.The results showed that:1) The weighted model based on spectral angular distance criterion had the highest accuracy,whose coefficient of determination (R2) was 0.999 7 and the root mean square error (RMSE) was 3.427 5;2) The weighted model based on Euclidean distance criterion and cubic polynomial fitting model are next to the above method,whose R2 were 0.998 1 and 0.998 1,and RMSE were 8.572 5 and 8.473 5,respectively.In conclusion,the weighted interpolation model based on spectral angular distance measurement could be used for rapid meat freshness detection with the highest accuracy among the above 3 methods.Keywords：meat freshness;spectral angular distance;Euclidean distance;spectral analysis;spectral detection1|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming at the problem that the existing pneumatic seed metering device is difficult to achieve fine seeding for small-sized seeds such as millet,and according to the physical characteristics of millet shape,a spoon-aspiration combination millet precision metering device was designed by optimizing the structure of the metering device to study on the influence of the structure and parameters of the key components of the seed metering device on the seeding performance of millet.Using the JPS-12 seed metering device performance test bench,three-factor and three-level orthogonal experiments were carried out.The rotation speed of the seed metering axis,the spoon position angle and the central angle of seed spoon were considered as test factors.The qualification index of hole seed number,the qualified index of the distance between holes,the void index and the coefficient of variation of the distance between holes were taken as the test indexes.The significant effects of various experimental factors on the performance indicators were analyzed.The results show that the optimal working parameters of spoon-aspiration combined small-size seed precision metering device were central angle of seed spoon 45°,spoon position angle -15° and rotation speed of the seed metering axis 10 r/min.The comprehensive performance test index of optimized seed metering device was 88.7% of the qualified index of hole number,87.7% of the qualified index of hole spacing,1.3% of the hole index and 12.3% of the variation coefficient of hole spacing.In conclusion,the seed metering device meets the precision seeding and agronomic requirements of small grain crops.Keywords：pneumatic metering device;millet;precision seeding;structural design;performance test6|10|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The aim of this study is to accurately describe the pressure at any point inside the bulk material in silo.By considering that the interface between bulk material in silo and silo wall and the interface between bulk materials are all not necessary in the critical state of relative sliding and thus the ratio of the actual friction force to the normal force on the contact interface is less than or equal to the maximum static friction coefficient,"effective coefficient of friction",which represents the ratio of actual frictional stress and normal stress on the contact surface of two objects,is defined.Firstly a finite element numerical simulation for the distribution of the effective coefficient of friction in grain pile is carried out,and the mathematical expression for the distribution law of effective friction coefficient on silo wall and effective friction coefficient in interior of grain pile are presented;Then based on the distribution law of effective friction coefficient of grain pile and the bulk material in the silo is divided and static equilibrium analysis of grain pile infinitesimal is used,the calculation method of static pressure field of bulk material in silo is presented;The calculated results of this study are compared and analyzed with the numerical simulation values and Janssen formula.The results show that:1) The vertical and horizontal pressures at any point in the bulk material and the lateral pressures of the silo can be calculated,and the non-uniformity of the vertical pressure distribution on horizontal plane of grain pile can be obtained by the method of this study;2) Compared with the numerical simulation results,the pressures at different depths in interior of grain pile calculated by the method of this study are different;3) Compared with the results of numerical simulation and Janssen formula,the lateral pressure of silo calculated by the method of this study has little difference.Keywords：grain pile;silo;effective friction coefficient;pressure field;frictional stress;non-uniform distribution1|7|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to scientifically evaluate the land ecological status under the combined action of natural and human activities and better reflect its spatial heterogeneity,this study takes pixel as evaluation unit and constructs a land ecological status evaluation model (LEI model) that covers five remote sensing parameters including land use type,vegetation coverage,soil moisture,bare soil index and soil brightness.The spatial differences of land ecological status in Chen Barag Banner,the core area of Hulunbuir grassland are investigated,and the main limiting factors are analyzed,the corresponding ways of land ecological regulation are then put forwarded.The results show that:The land ecological status of Chen Barag Banner is gradually deteriorating from northeast to southwest spatially,and the overall land ecological status of Chen Barag Tiger Banner displays a trend of deterioration from 2000 to 2010.The area of land ecological status in "general" has increased from 65.75% to 69.75%,and the proportion of "deteriorated" and "improved" areas has increased 12.59% and 5.19% respectively,and the deterioration process of land ecology in the East is faster than that in the west.The land use type and vegetation coverage are the main limiting factors affecting the land ecology in the study area.Keywords：land ecosystem status;remote sensing parameters;synthetic assessment;limiting factor0|9|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to comprehensively consider the impact of the amount of arable land and other factors on food production,this study used LMDI approach and decomposed the factors of arable land utilization for grain production into 4 factors including arable land area,multiple crop index,planting structure and intensive cultivation.And studying the mechanism of changes in national food production from 1996 to 2016.The results showed that:1) The amount of arable land area in China continued to decrease and the spatial characteristics were the decline in the southern region and the increase in the northern region,which had also brought a significant shift in grain production capacity to the north.2) Grain yield per unit and the multiple cropping indexes were all the factors that promoted production,among which,the increase in grain yield per unit contributed the most to the increase in total grain production.The decline of arable land area and the adjustment of planting structure during the period were the factors that reduced grain production.The results obtained from this study suggests that in the process of urbanization,the reduction of arable land is unavoidable.To ensure food security,it is necessary not only to strictly protect arable land,but also to strengthen the strategic measures for storing grain in technology and continuously improve the grain yield per unit and multiple crop index to stabilize and optimize grain production level.Keywords：arable land area;multiple crop index;planting structure;grain yield per unit;grain production capacity;China1|8|8<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To clarify the changes of the planting structure of major food and oil crops in China,based on the provincial production data of major food and oil crops in china from 1951 to 2015,the theory of advantage index was used to analyze the temporal and spatial variation characteristics of the dominant food and oil crop production.And the driving factors that affected the changes of the food and oil crops planting structure in China were explored.The results showed that the planting area of rice,maize and peanut in China increased,while the planting area of wheat and soybean decreased during 1951 and 2015.The total production and average yield of all crops increased significantly.From 1951 to 2015,the planting structure of food and oil crops changed most significantly in Northeast China and North China.The area of rice and maize increased significantly in Northeast China,while the area of wheat decreased significantly.The area of maize and peanuts in North China increased significantly,while the area of soybean decreased significantly.Keywords：rice;wheat;maize;soybean;peanut;planting structure5|7|13<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To understand the impact of carbon emissions on the measurement of total factor productivity of rice and its extent,based on the rice panel data of 23 provinces in China from 2006 to 2015,the impact of carbon emissions on total factor productivity of rice and provincial difference are empirically analyzed.The Malmquist-Luenburger productivity index based on directional distance function and panel Tobit model are adopted in this study.The results show that:1) Considering carbon emissions,China's total factor productivity of rice displays first increasing and then decreasing trend,and the overall progress is deteriorating.Only a few provinces have achieved growth.2) The overall growth driving force is transformed from technological efficiency improvement to technological advancement,while the provinces that achieve growth are mainly benefited from the dual role of technological advancement and technological efficiency improvement.3) The "high carbon" and "low carbon" provinces have obvious cross-distribution patterns of T-shaped from northand southto east and west.4) The growth of rice TFPC and its decomposition index are benefited from the level of urbanization and industrialization,but they are restricted by the level of economic development and the rate of disaster.5)The difference between high and low carbon groups is mainly reflected in the role of fiscal support and planting structure adjustment in the "low carbon" provinces.Keywords：carbon emissions;rice;total factor productivity;technological advancement1|7|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The aim of this study was to accurately grasp the substitution relationship between corn production factors under the background of rapid labor price increase.Based on the transcendental logarithmic production function model,the factor output elasticity from the national and regional levels was investigated by using the provincial panel data from 2000-2016.An empirical study was conducted on the elasticity of substitution between elements,and the direction of technology selection for corn production in China was discussed.The results show that:1) China's corn production effectively replaces the labor factor,the substitution elasticity was 1.099,and the rapid development of corn harvest mechanization played an important role;2) Compared with the northern spring corn area and the Huanghuai sea summer corn area,the southwest advantage of China The replacement speed of labor in the corn area was accelerated;3) The output level of chemical fertilizers continued to decline during the sample period.The degree of substitution for labor and machinery was gradually weakening;4) The production of corn adopted mechanical technology and biochemical technology As supplementary technology.China's corn production needs to further strengthen the combination of agricultural machinery and agronomy,and promote mechanization development according to local conditions.Keywords：corn production;factor substitution;output elasticity;growth path;empirical research0|7|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to clarify whether there is a spatial effect of sheep and goat meat price fluctuation in China,based on the inter-provincial panel data from 2001 to 2016,a spatial correlation test is conducted from the perspective of geography.An empirical test is carried out on the long-term trend change and cycle change of sheep and goat meat price in China by using the Spatial Durbin model.It is found that sheep and goat meat price in China is not simply randomly distributed and it has obvious spatial clustering characteristics.The regression results of the Spatial Durbin Model show that sheep and goat meat price and its changes are not only affected by the relevant factors in the region,but also have a positive spillover effect on neighboring sheep and goat meat price.At the same time,spillover effect shows an increasing trend over time.The spatial decomposition effect shows that production of sheep and goat meat,beef price,pork price and purchasing power can effectively influence the long-term trend change of sheep and goat meat price.The cyclical change of sheep and goat meat price is only related to the beef price and purchasing power in the model.Keywords：sheep and goat meat;price fluctuation;spatial effect;decomposition effect0|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to scientifically evaluate the implementation effect of beef cattle improved variety subsidy policy in China and make an empirical prediction of its trend,this study evaluates and reflects the beef cattle improved variety subsidy.The results show that:Since the implementation of the beef cattle improved variety subsidy policy,it has played an active role in improving the level of beef cattle breeding and promoting the construction and improvement of beef cattle breeding system.However,during the implementation process of beef cattle improved variety subsidy,the phenomenon of "three low and one fuzziness" exists.In other words,the farmers' cognition degree towards beef cattle improved variety subsidy is low,the patronage level of policy is low,the farmers' satisfaction level on policy is low and the charge standard of artificial insemination is obscure.In conclusion,this policy does not realize the original goal well.To some extent,the policy is a failure,and maybe abolished later.To promote the improved variety of beef cattle,it should adjust measures to local conditions and innovate the working ways to avoid the mismatch between policy supply and demand,and the ineffective policy.Keywords：beef cattle;farmers;improved variety subsidy;frozen semen of beef cattle0|8|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To raise scale level of laying hens through implementing diversified marketing strategy,following a logical main line of "risk perception-diversified marketing strategy decision-scale of laying hens",this context bases on the survey data of 5 major egg producing provinces from National System for Layer Production Technology and adopts endogenous switching regression model with modified selectivity to estimate the layer farmers' selection behavior of implementing diversified marketing strategy and the breeding scale equation of laying hens.The results reflect that the scale-up effect of laying hens with diversified sales strategy is significant,enabling average scale of laying hens to 2 839.The higher the ratio of farming income to total household income,the higher education level and degree of non-independent operation,the stronger the market risk perception ability and the younger layer farmers are more inclined to implement diversified marketing strategies.Keywords：risk perception;diversified marketing strategy decision;layer cultivation scale;endogenous switching regression model;average treatment effect0|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to understand the influence of social network and information cost on farmers' willingness to adopt ecological farming,based on the survey data of 2 068 households in Jiangxi Province,An empirically analyses was conducted by the binary Probit model,An interaction term was introduced to test the moderating effect of social network on information cost.The results showed that:1) The social network had positive impact on the willingness of farmers to adopt ecological farming,while the information cost displayed negative impact on the willingness of farmers to adopt ecological farming,and the social network could regulate the inhibitory effect of information cost.2) In addition to the above influencing factors,farmers' willingness to adopt ecological farming was also influenced by gender,age,education level,cultivated area and proportion of non-agricultural income.Therefore,on the one hand,the construction of rural social network should be strengthened.The demonstration role of various cooperatives or family farms (large professional growers) should be used to improve farmers' ecological farming willingness when promoting the construction of various information exchange platforms.On the other hand,the publicity and promotion of various ecological farming technologies should be strengthened to effectively reduce the cost for farmers to obtain relevant information.Keywords：social network;information cost;ecological farming;willingness0|8|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
