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- Abstract：In order to quantitatively evaluate the overall gap on agricultural science and technology(S&T)level between China and the developed countries, based on the consideration on theory of agricultural S&T power, an evaluation index system was designed through multidisciplinary, multiple-groups, multiple-rounds discussions in this study. The index system mainly consisted of five primary indices, including the S&T supporting ability, agricultural technology level, S&T efficiency, S&T condition and S&T output, and 19 secondary indices. The relevant data on agricultural sector in China and other developed countries were collected based on the designed index system. A preliminary evaluation was then conducted for the realization degree of agricultural S&T power in China based on an analytic hierarchy process. The results showed that the degree of the implementation of China's agricultural S&T power was 62% presently. There was still a big gap of agricultural S&T power between China and other developed countries. China has just walked over two-thirds of the way to become a country with strong agricultural S&T power, and is in the “climbing camp” phase. It is necessary for China to make more efforts in increasing agricultural S&T input intensity, agricultural S&T human resources and enterprise R&D strength, and improving agricultural labor productivity, agricultural products processing value-added and land productivity. These measures would ensure that China would become into a counrty with great power in agricultural S&T of the world by 2050.Keywords：agricultural science and technology;powerful country of science and technology;index system;evaluation;modernization of agricultural science and technology33|14|10<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To establish a unified evaluation method, which is prerequisite for salt tolerance mechanism research, reports on the evaluation strategies in cotton salt tolerance since 1990 were summarized. Meanwhile, the evaluation protocols and corresponding results related to cotton salt tolerance during seed germination, seedling stage and whole growth stages were analyzed. The results showed that the unified evaluation protocols of salt-tolerance in upland cotton are: Under laboratory conditions, the cotton seeds germinating ratio is conducted by using the folding filter paper and keeping it wet at room temperature after treatment with 150 mmol/L NaCl solution at seed germination stage; Under outdoor conditions, the cotton seedlings survival ratio was determined after treatment with 0. 40% NaCl in salt pool at three leaves seedling stage.Keywords：cotton;salt tolerance;germination stage;seedling stage;evaluation protocol27|11|10<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore metabolites with medicinal and edible values in cotton flowers, the flowers of Gossypium hirsutum L. and Aurea helianthus were sampled on the day of flowering to carry out metabolomics analysis. A total of 465 metabolites were detected by metabolomics sequencing. The fold change and VIP(Variable importance in projection)were combined used to screen the differential metabolites. A total of 269 metabolites showed significant changes between G. hirsutum L. and A. helianthus, while there were no significant difference in the contents of 196 metabolites. There were 29 metabolites only detected in A. helianthus, including amino acids and derivatives, phenolic acids, flavonoids, lignans and coumarins and etc. There were 41 metabolites only detected in G. hirsutum L. , including flavonoids, phenolic acids, tannins and etc. The results above showed that cotton was rich in flavonoids, amino acids and derivatives, phenolic acids, alkaloids, organic acids, lipids, nucleotides and derivatives, tannins and coumarins.40|11|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to establish a quantitative near-infrared spectroscopy(NIRS)model for the rapid analyze of chemical components of energy conversion in stems and leaves of energy sorghum, and to explore the optimization method of the model, 27 sweet sorghum and 28 biomass sorghum varieties were selected. The contents of soluble sugar, cellulose, hemicellulose, lignin and ash in the stem and leaf samples of each variety were determined by chemical analysis methods. Meanwhile, the differences in the content of the two types of energy sorghum were analyzed and compared, and the correlation between the content of the stems and leaves was investigated. The partial least squares(PLS)was used to establish the NIRS models to analyze main chemical components of energy sorghum stems and leaves, and the model was optimized by first derivative and competitive adaptive reweighted sampling(CARS)selection. The results showed that there were significant differences in stem soluble sugar, cellulose, hemicellulose, lignin and leaf soluble sugar between sweet sorghum and biomass sorghum(P<0. 01). In the process of establishing NIR model, the coefficient of determination of cross validation(R2CV)was 0. 82-0. 99 by “first derivative-CARS”. The ratio of performance to deviation of cross validation(RPDCV)and ratio of performance to deviation of validation(RPDV)of stem soluble sugar, cellulose, hemicellulose and lignin model, and leaf soluble sugar, cellulose and ash model were all more than 3. 0, which improved the prediction performance of the model significantly.Keywords：near-infrared spectroscopy;energy sorghum;lignocellulose;partial least squares;model optimization24|10|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to clarify the degradation process and residual properties of the biodegradable plastic film in the semi-arid area of western Liaoning Province, combined with scanning electron microscope(SEM)and Fourier transform infrared spectroscopy methods, a two-years field study was conducted in National Agricultural Experimental Station for Agricultural Environment in Fuxin. The experiment included two treatments, which were conventional plastic film mulching(CPF)and biodegradable film mulching(BPF). The results showed that the degradation of biodegradable plastic film started from the seedling stage(about 40 d). The degradation of plastic film entered the rupture stage at jointing stage of maize and entered the disintegrating stage after heading stage. With the increase of mulching years, the residual amount of mulching film increased accordingly. The cumulative weight of residual film on the surface of common mulching film and biodegradable mulching film increased by 165% and 47%, respectively and the total amount of residual film increased by 80% and 21%, respectively. The residual amount of plastic films decreased with the deepening of the soil layer, however, with the increase of the mulching years, the proportion of the residual film in the deep soil to the total residual film increased. The proportion of common plastic film increased from 8. 2% to 12. 4%, while the proportion of biodegradable plastic film increased from 2. 9% to 3. 7%. After 2 years of mulching, the number of pieces of common and biodegradable plastic films in the topsoil was 2. 77 million and 2. 36 million pieces/hm2, respectively, and the mass of films was 73. 6 and 57. 6 kg/hm2, respectively. In conclusion, compared with common plastic film, PBAT biodegradable plastic film can achieve self-degradation and reduce farmland residue. Therefore, it is feasible to replace common plastic film for corn mulching cultivation in semi-arid areas in western Liaoning Province.Keywords：conventional plastic film;biodegradable plastic film;degradation;residual characteristics27|13|7<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to promote mountain apple quality and efficient production in the hilly-gully region of northern Shaanxi, the trunk and dispersal-stratified canopy used in traditional sparse planting orchard were transformed into small and sparse canopy, spindle or cylinder canopy, high stem and open-center canopy, and open-center canopy in this study. The intracoronal light transmittance, crown size, number of annual branches and fruit-bearing branches and their composition proportion, and fruit yields, fruit quality and fruit output and others of different canopy were monitored and estimated. The results showed that: Compared with the trunk and dispersal-stratified canopy, the crowns of high stem and open-center canopy and open-center canopy trees were large and flat, and their intracoronal light transmittance were higher. The foliage branches and short branches of open-center canopy accounted for 61. 21% of the total annual branches, and the tree vigour was moderate to the upper. The foliage branches and short branches of trunk and dispersal-stratified canopy, small and sparse canopy, and high stem and open-center canopy accounted for more than 70. 00% of the total annual branches, and the tree vigour all were weaker. The short fruit-bearing branches of open-center canopy accounted for 60. 68% of the fruit-bearing branches, and the middle fruit-bearing branches accounted for 28. 67%, which were beneficial to high quality and high yields in consecutive years. The short fruit-bearing branches of trunk and dispersal-stratified canopy accounted for 85. 00%, and the middle fruit-bearing branches accounted for only 8. 79%, which were easy to form alternate bearing. The fruit yields of trunk and dispersal-stratified canopy were the highest among different canopies, and followed by open-center canopy. The fruit quality, fruit uniformity and fruit price of open-center canopy were the highest, and trunk and dispersal-stratified canopy were the lowest. The economic output value of open-center canopy was the highest, followed by trunk and dispersal-stratified canopy, and high stem and the open-center canopy was the lowest. By comprehensive comparison, in the hilly and gully region of northern Shaanxi, the trunk and dispersal-stratified canopy of traditional sparse planting orchard should be transformed into an open-center canopy.Keywords：mountain apple;canopy transformation;intracoronal light transmittance;number and proportion of branches;economic output value23|11|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to improve the efficiency of fertilizer utilization in apple production and solve the problems of tree growth, difficult to flower and fruit quality decline, caused by large amount of fertilizer application, four Red Fuji orchards of different tree ages under normal management were selected in Yan'an City, Shaanxi Province from 2017 to 2019 by using self-made bioactive element compound formulation. Treat with conventional fertilization(control)and increased application of bioactive element, the effect of bioactive elements on the orchard nitrogen utilization and growth and development of Red Fuji apple was explored from the aspects of soil physical and chemical properties, tree growth and development, and fruit quality, The results showed that: 1)After the bioactive element treatment, the total nitrogen content of the soil increased by 4. 69%~51. 35%, and the improvement effect was more obvious in the young tree orchard. 2)After treatment, the number of flower buds of young trees increased year after year, with an average increase of 58. 42%, and the proportion of flowering trees increased by 22%. 3)The fruit yields and aroma of the 4 participating orchards were increased. 4)The partial productivity of fertilizer in the 3 orchards increased by 11. 32% on average, showing an overall increasing trend. The application of bioactive element can promote early flowering and early fruit for young trees, and increase the yield and quality of mature trees. In conclusion, the application of bioactive elements is an effective measure for the efficient use of fertilizers and high-yield and high-quality production of Red Fuji apples in the Loess Plateau.Keywords：apple;bioactive;fertilizer utilization;number of flower buds;fruit aroma23|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore the genetic variations of important traits and fruit phenotypes of non-astringent persimmon, 170 individual F1 hybrids of ‘Fuyu'בAkagaki' were used as materials. The diversity of gender type, fruit astringency type and phenotype were investigated through trait investigation and determination. The correlation among phenotypic indexes and the similarity among individual plants were analyzed by Pearson correlation analysis and cluster analysis. The results showed that: 1)In the hybrid F1 progeny population, the separation ratio of female plants, male plants and monoecious plants was close to 4∶1∶2. 5, and the separation ratio of PCA persimmons, PVA persimmons and PVNA persimmons was about 4∶1∶2. 7. 2)Among 148 fruit samples, the variation coefficients of 5 phenotypic quantitative traits ranged from 12. 36% to 34. 64%, which indicated the phenotypic diversity of fruit was high. The variation coefficient of single fruit weight was the largest. 3)The Shannon-Weinner diversity index of fruit shape was 1. 746, with the most abundant genetic diversity. 4)The mid-parent heterosis values of single fruit weight, fruit longitudinal diameter, and fruit transverse diameter were less than 0, indicating that heterosis was decreasing in F1 generation population. The diversity of gender types, fruit astringency types and fruit phenotypes in the F1 generation were relatively high. The study on the genetic variation of non-astringent persimmon provided a theoretical and material basis for the genetic improvement of PCNA persimmon.Keywords：non-astringent persimmon;F;1;progeny;gender type;fruit astringency type;fruit phenotypic diversity24|11|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To utilize the current chestnut germplasm resources scientifically and manage and preserve them efficiently. Taking 279 Castanea mollissima Bl. germplasm resources from 12 provinces(cities and autonomous regions)as original materials, the multi-times random sampling based on SSR molecular markers was conducted by using UPGMA cluster method. The allele-preferred sampling method and random sampling strategy were compared according to SM or Dice similarity coefficient. The effective number of alleles, Nei's gene diversity index and Shannon's information index of two core sample groups were compared to determine the optimum building method. T-test and the principle coordinate analysis method were used to confirm on the primary core collection. The results showed that: The allele preferred sampling method was more representative with higher values of genetic diversity index compared with the random sampling strategy; The method of stepwise clustering according to SM similarity coefficient was better than Dice similarity coefficient; The principal coordinate analysis and morphological traits analysis showed that the core collection constructed by allele preferred sampling method and according to SM similarity coefficient could represent genetic diversity of initial collection more comprehensively. The 68 core collection included 24. 37% germplasm samples of initial collection. The effective number of alleles, Nei's gene diversity index and Shannon's information index were respectively 1. 539, 0. 329 and 0. 502, which were higher than those of initial collection. In conclusion, the core collection could represent the genetic diversity of the whole chestnut resource fully. The studies showed that UPGMA cluster method according to SM similarity coefficient based on SSR molecular markers combined with allele-preferred sampling strategy was an appropriate method for the construction of primary core collection of chestnut.25|13|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to understand the biological information of bovine miR-2439-5p, preliminarily explore the interaction between miR-2439-5p and host gene MRTFA(Myocardin related transcription factor A), and further understand the tissue expression of miR-2439-5p, bioinformatics methods such as species conservation analysis, upstream sequence CpG island analysis, promoter prediction, transcription factor prediction, target gene prediction, gene ontology enrichment analysis and signal pathway enrichment analysis were used to predict “transcription factor-miRNA-mRNA” regulatory network of miR-2439-5p and the tissue expression profile of miR-2439-5p was also analyzed. The results showed that: 1)miR-2439-5p was bovine-specific miRNA, intron miRNA and miRNA*. 2)miR-2439-5p may be regulated by transcription factors such as C/EBPβ and RARα. 621 target genes were predicted to be enriched in AMPK signaling pathway, mTOR signaling pathway and biosynthesis of unsaturated fatty acids. 3)miR-2439-5p was relatively highly expressed in the kidney tissue of 28-month-old Jiaxian Red cattle, which was significantly different from that in muscle and back fat(P<0. 01); it was relatively highly expressed in back fat of 28-month-old Wagyu, which was significantly different from that in liver and spleen(P<0. 05); there was no significant difference in different tissues of 28-month-old Guyuan cattle(P>0. 05). In conclusion, miR-2439-5p may feedback regulate host gene MRTFA, thereby regulate bovine adipocyte differentiation. This study provides research direction and theoretical basis for further exploration of the function and mechanism of miR-2439-5p.Keywords：bovine;miR-2439-5p;“transcription factor-miRNA-mRNA” regulatory network;tissue expression profile analysis27|12|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to analyze the structural characteristics of JAG1 protein in Cashmere goats and its expression pattern in different hair follicle growth periods, three two-year-old Inner Mongolia cashmere goat ewes with similar body weight were selected from Alashan breeding farm. The similarity of the amino acid sequence of JAG1 between Cashmere goat and other species was compared by bioinformatics method, and the physicochemical properties and structural characteristics of JAG1 protein were analyzed. Immunohistochemistry and real-time fluorescence quantitative PCR were used to detect the expression sites and amounts of JAG1 in Inner Mongolia Cashmere goat skin. The results showed that the similarity of JAG1 amino acid sequence in Cashmere goat and sheep was 99. 5%. The signal peptide of JAG1 protein was located in the amino acid sequence of 1-29 containing a splice site and a transmembrane structure. There were 61 serine, 26 threonine and 19 tyrosine phosphorylation sites. 63 O-glycosylation sites, and 6 N-glycosylation sites. It was an unstable hydrophilic protein. The expression of JAG1 protein was not detected in hair follicle catagen(January)and telogen(April). However, JAG1 protein was expressed in the dermal papilla cells at the early stage of anagen(July)and anagen(September)hair follicle. JAG1 mRNA was expressed in the skin of Inner Mongolia cashmere goat in the four stages of hair follicle. With the development of hair follicles, the expression level of JAG1 mRNA gradually increased, and the expression level of JAG1 mRNA in the skin during the anagen was significantly higher than that in other stages(P<0. 05). In conclusion, the animo acid sequence of JAG1 in cashmere goat is relatively conservative in the process of species evolution, and the expression of JAG1 gene is increased in the early stage of anagen of hair follicle of Inner Mongolia Cashmere goat. This study provides a theoretical basis for further study on the regulation of hair follicle development by JAG1 gene in Inner Mongolia Cashmere goat hair follicle.Keywords：Inner Mongolia Cashmere goat;JAG1;bioinformatics analysis;expression pattern analysis26|12|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The aim of this study was to analyze the effect of low ambient temperature on H9N2 influenza virus infection in mice. A total of 120 male 6-8 weeks old SPF BALB/c mice were randomly assigned into 4 groups: room temperature group without infection(PBS, (20±2)℃), cold treatment group without infection(PBS, (10±2)℃), room temperature group with H9N2 infection(H9N2, (20±2)℃)and cold treatment group with H9N2 infection(H9N2, (10±2)℃). After infection, the clinical symptoms, mortality, pulmonary pathological changes, the degree of pulmonary edema, the level of cytokines of lung and viral titers of lung were observed. The results indicated that: 1)Compared with H9N2 virus infected mice in normal temperature group, the clinical symptoms of H9N2 virus infected mice in low temperature were significantly aggravated, and the body weight was significantly reduced, the survival rate was reduced from 95% to 67%, and the degree of pulmonary edema and lung tissue were more serious; 2)There was no significant difference in the levels of TNF-α and IL-1β between the two groups, but they were significantly higher than that in the non-infected mice(P<0. 01); 3)Compared with the normal temperature group, the viral load in lung tissue of H9N2 virus infected hypothermia group was significantly increased(P<0. 01). In conclusion, low ambient temperature could aggravate the severity of H9N2 influenza virus infection in mice. This study will help us further understand the relationship between low ambient temperature and influenza virus infection, and take effective measures to prevent influenza infection.Keywords：H9N2 avian influenza virus;low temperature;lung;mice;cytokines24|11|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The aim of this study was to investigate the prevalence of mcr-1 and the co-tansfer of mcr-1 with ESBLs genes in Escherichia coli from food-producing animals in Sichuan Province. The sensitivity of mcr-1 to different antibiotics was detected by broth microdilution method; The ESBLs gene type of mcr-1 positive strains were detected by PCR; The drug resistance mechanism of co-transfer of mcr-1 and ESBLs gene was analyzed by plasmid conjugation transfer test. The results showed that: The detection rate of mcr-1 in 190 E. coli isolates was 36. 84%, and 75. 71% mcr-1 positive strains was detected ESBLs gene simultaneously, mainly blaTEM-1, blaCTX-M-55and blaCTX-M-14as the dominant genes; The resistant rate of mcr-1 positive strains to aztreonam, cefotaxime and colistin was very significantly higher than that of negative strains(P<0. 01); The rate of plasmid conjugation was 47. 14%. The transconjugants with mcr-1 and ESBLs of co-transfer had acquired resistant phenotype and genotypes from parental strains. In conclusion, in the food-producing animals source of E. coli in Sichuan Province, the coexistence of mcr-1 and ESBLs genes is widespread and the resistant genes is easy to spread horizontally, which is of great significance to the production of multiple drug resistance of strains.Keywords：food-producing animals;Escherichia coli;mcr-;1;ESBLs;genes;co-transfer23|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Insufficient prediction accuracy and easy to fall into local minimums are the problems existed in traditional hog price prediction methods. In order to predict hog price more accurately, three machine learning models, e. g. Random Forest Regression(RFR), Extreme Gradient Boosting(XGBoost)and Light Gradient Boosting Machine(LightGBM)were adopted in this study. The improved temporal convolutional network(TCN)model method was also used. The weekly hog price data from 2011 to 2020 in a province in Southwest China preprocessed by Z-Score standardization were taken as study object to investigate the hog price prediction. The TCN model prediction results were shown as follows: The mean square error(MSE)was 0. 340 606, the mean absolute error(MAE)was 0. 288 424, and the coefficient of determination(R2)was 0. 995 683, which were better than the other three machine learning models. Comparing the results of the improved temporal convolutional network model with the results of the three machine learning models, the three indicators of the most effective XGBoost were increased by 26%, 8%, and 0. 15%, respectively. In conclusion, the improved temporal convolutional network model can predict the price of hog more accurately.Keywords：hog price;time series forecast;temporal convolutional network;cross-validation;grid search;machine learning24|14|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to compare and verify the stability of different leaf area index(LAI)machine learning estimation models after migration, the multispectral image data of rice fields in Ezhou, Hubei Province and Hainan Province obtained by unmanned aerial vehicle(UAV)were used for. The rice LAI of Ezhou experimental field was estimated by using eight vegetation index empirical model and three machine learning methods, and then validated in Hainan experimental area. The results showed that: 1)The accuracy of the nonlinear model was better in the modeling set test of Ezhou experimental data. The coefficient of vatiation(CV)of using nonlinear fitting model was 31. 05%. However, the accuracy of the NDRE decreased seriously when it was extended to Hainan experimental area(CV=74. 90%), and the portability was poor. 2)Linear model and machine learning model showed better stability after model validation on other dataset. The CV of GBR two-band model in Ezhou data modeling set was 28. 91%, and that of Hainan data validation set was 26. 58%. 3)The CV of EVI2 linear fitting model in Ezhou data modeling set was 33. 78%, and that in Hainan data validation set was 27. 90%. Finally, the empirical model constructed by EVI2 was used to predict LAI of two different rice varieties(Luoyou 9348 and Fengliangyou 4)at different growth stages. The results showed that Luoyou 9248 was a nitrogen efficient variety under the same nitrogen level.Keywords：rice;leaf area index;vegetation index;nitrogen efficient36|12|9<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In recent years, with the continuous improvement of agricultural development, excessive use of chemical fertilizers, pesticides, and agricultural plastic films have become the main reasons that cause agricultural non-point source pollution in China. To explore the regional differences and evolution characteristics of agricultural non-point source pollution risk since the 1990s in China. ArcGIS spatial analysis technology was employed in this study to analyze the spatial distribution and long-term evolution characteristics of fertilizers, pesticides, and agricultural plastic film pollution in nine major agricultural regions and provinces in China. The results show that the overall use of chemical fertilizers, pesticides, and agricultural plastic films is increasing year by year in China from 1991 to 2018, and the grade of non-point source pollution is increasing, and the problem of non-point source pollution is more prominent in farmland. The usage amount of chemical fertilizers on land increased by 101. 5%, and the overall pollution level increased from a lower pollution level to a higher pollution level. The usage amount of pesticides on land increased by 97. 6%, and the overall pollution level changed from a lower level to a higher level; the usage amount of agricultural plastic film on land increased by 238. 2%, and its pollution level changed from a low level to a higher level. The pollution levels of chemical fertilizers, pesticides and agricultural plastic films have changed from the lower pollution levels in the early period to the current higher pollution levels in the nine agricultural areas. The degree of increase of non-point source pollution of chemical fertilizers is the most prominent in Southern China, Huang-Huai-Hai Plain and Loess Plateau. The increase of non-point source pollution of pesticides is the most prominent in Huang-Huai-Hai Plain, Middle-lower Yangtze Plain and Southern China, the pollution level of agricultural plastic films non-point source pollution has increased most prominently in Northern arid and semiarid region, Southern China and Huang-Huai-Hai Plain. The pollution degree of chemical fertilizers, pesticides, and agricultural plastic films in various provinces showed different degrees of increasing trends. In conclusion, the non-point source pollution of chemical fertilizers became more serious in Henan, Hainan, Hubei, Guangxi, Shaanxi and Xinjiang, the non-point source pollution increase of pesticides in Hunan, Jiangxi, Fujian, Guangdong and Hainan is the most obvious, and the agricultural plastic film non-point source pollution has increased significantly in Shanghai, Xinjiang, Fujian, Hainan, Gansu, Shandong and Zhejiang.Keywords：agricultural non-point source pollution;spatial distribution;evolution characteristics26|11|11<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The purpose of the study was to construct a diagnostic concept framework for land health based on social-ecological systems(SESs), and achieve sustainable land management. Knowledge domain mapping analysis was conducted on land health based on CiteSpace literature review method. The results show that: 1)The concept evolution of land health can be used as diagnostic criteria for determining land ecosystem and social-economic functioning healthily; 2)Researches on land health are focused on the mechanism, methodology, and practical management, indicating a diverse and distinct characteristic; 3)The diagnostic framework mainly consists external drive subsystem, internal drive subsystem and land use system, and successfully integrates socio-economic system and land ecosystem; 4)The structure of diagnostic framework is problem oriented, which is strongly adaptive and can constantly be revised according to the evaluation results. In conclusion, the diagnostic framework bridges the gap regarding the cognition of processes and cross-feedback mechanism of human-land relationship. This study provides a novel insight to improve the harmony between humankind and nature.Keywords：land use;land health;social-ecological systems;mapping knowledge domain;diagnostic framework27|10|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Soil nematodes are widely distributed in the soil environment and their ecological indices are closely related to soil health. To explore the feasibility of using soil nematode ecological indices to characterize soil health status, soil nematode was taken as the research object by taking mortar black soil in the Mengcheng County of Anhui Province. The correlations among the total number of soil nematodes, nutritional groups, ecological indicators of soil nematodes and soil fertility conditions were analyzed. The crop yield indexes under the condition of long-term fertilization were determined. The results showed that: The soil fertility level of each fertilization treatment from high to low was NPK+PM>NPK+CM>NPK+S>NPK>CK; With the increase of soil fertility level, the Shannon-Weaver diversity index, the evenness index and Wasilewska index increased significantly, while the plant parasitic nematode maturation index decreased remarkably, and the soil became healthier; Meanwhile, compared with CK, the yields of NPK, NPK+S, NPK+PM and NPK+CM treatments increased by 337. 87%, 396. 14%, 495. 43% and 534. 24%, respectively. The results indicated that the changes of nematode ecological indicators could be used to characterize soil health.Keywords：long-term location fertilization;mortar black soil;soil nematodes;ecological indicators;soil health state30|11|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：EEPA(Edinburgh elssto-plastic adhesion)contact model was used to simulate soil tillage characteristics, and the influence of particle spherical shape on the simulation accuracy and computational efficiency of soil discrete element model was explored. The static accumulation angle, axial pressure, tillage resistance, tillage accumulation angle and other soil characteristics parameters of indoor soil were measured. The simulation parameters of single particle soil were determined and optimized, and the plastic deformation ratio was 0. 31, the adhesion energy was 26. 30 J/m2, the rolling friction coefficient was 0. 52, the recovery coefficient was 0. 58, the tangential stiffness factor was 0. 39, the static friction coefficient was 0. 67, and the bond branching index was 4. The discrete element coupling simulation model of soil-excavation plough shovel was established and the simulation parameters were verified. The error between the simulated and measured values of tillage resistance was 1. 70%. On the basis of the above research, with 13 mm as the equivalent particle size, the dimensions of four kinds of soil particles, including single-ball, double-ball, three-ball and four-ball, were determined. Six kinds of virtual soil grooves were established by filling methods such as single-ball, single-ball with variable particle size, double-ball, three-ball, four-ball and multi-ball mixing. Taking tillage resistance, tillage accumulation angle and simulation time as the test indexes, the simulation test of digging plough shovel tillage process was carried out. The test results showed that the error between the simulation value of tillage resistance and the measured value iwas less than 8%, and the six virtual soil grooves met the requirements of tillage resistance simulation. The error between the simulated and measured values of tillage accumulation angle was 2. 32%-20. 32%, and the error of tillage accumulation angle using virtual soil troughs such as single-ball variable particle size, four-ball and multi-ball mixing was less than 10%. The simulation time of single ball filling virtual soil trench digging plow shovel tillage was about 80. 44 min. Affected by the number of soil particles, contact relationship and particle ball type, the simulation time under other filling conditions was significantly increased. Considering the simulation accuracy and calculation efficiency, the single-ball particle filling method is suitable for the simulation of soil tillage resistance, and the four-ball or multi-ball mixed filling method is suitable for the simulation of tillage accumulation angle. This study provides a basis and reference for the modeling of soil-machine interaction discrete element simulation, the parameter selection of EEPA contact model, the determination of particle ball type and filling method.Keywords：soil tillage;discrete element;simulation;EEPA contact model;particle sphere type27|10|11<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to clarify the differences of maize grain breakage resistance of different maize cultivers during mechanical grain harvesting and their influencing factors, 13 maize cultivars were taken as materials to study the dynamic change characteristics of grain broken rate, moisture content, and hardness of different maize cultivars in different harvest dates, and analyze the relationship between grain broken rate and moisture content and hardness. The integral method was used to evaluate the resistance of different maize varieties to kernel breakage. The results showed that: With the postponement of harvest time, the breakage rate of grain decreased rapidly and then increased slightly. The moisture content of grains gradually decreased, and the hardness of grains gradually increased. There were significant differences between different maize varieties. The relationship between the breakage rate and the moisture content of grain conformed to the quadratic curve, and the broken rate was the lowest when the moisture content of grain was 19. 70%. There was a significant negative correlation between the breakage rate and the grain hardness, and the endosperm puncture strength had the highest correlation with the breakage rate. When the endosperm puncture strength was 88. 35 N, the broken rate was the lowest. There was a significant negative correlation between grain hardness and moisture content. In conclusion, reducing the moisture content of grains and improving the mechanical strength of the grains are the key to enhancing the resistance to grain breakage and reducing the breakage rate of maize. There were significant differences in kernel hardness and breakage resistance of different maize varieties. Under the conditions of similar moisture content, maize varieties with strong breakage resistance have higher kernel hardness. The endosperm penetration strength of the grain hardness index can be used as an important index for selecting suitable mechanical grain harvesting maize cultivars. All the flint corn varieties tested, semi-dent corn ‘Zhongyu 3', semi-flint corn ‘Liaohe 308', ‘Xianyu 1171' and dent corn ‘Zhenghong 6' have strong grain breakage resistance and can be used as suitable for mechanical grain harvesting.Keywords：maize;mechanical grain harvesting;grain broken rate;kernel hardness;grain moisture content;breakage tolerance24|10|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to improve the accuracy of the numerical simulation of the anti-blocking device, the discrete element parameters of corn stalk were calibrated by combining with physical and simulation experiments. The model of the simulated compression test was established based on Hertz-Mindlin with bonding contact model. Simulation experiments were designed by using the relative error of critical load between physical and simulation experiments as the experimental index. Factors that have positive effects to the experimental index were screened by Plackett-Burman design. The experiments were designed by Box-Behnken experimental design to optimize the discrete element model of corn stalk. The experiment result shows that contact radius and shear stiffness per unit area had an extremely significant influence on the index(P<0. 01), and the normal stiffness per unit area had a significant influence on the index(0. 01Keywords：corn stalk;discrete element;critical load;Plackett-Burman design;response surface methodology26|10|19<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to clarify the influence of solar radiation on the performance of the seepage ventilation and temperature control system of grain bulk established in this study, the seepage ventilation and temperature control process of grain bulk with radiation heat source outside the silo roof were monitored and analyzed by experimental method. The results show that: Increased ventilation can strengthen the heat insulation effect of air layer above grain bulk during the process of seepage ventilation and temperature control; With the increase of ventilation rate, the duration of high efficiency cooling section increases significantly under the condition of radiant heat source outside the silo roof; The temperature control effect of the seepage ventilation and temperature control system on the skin of the grain bulk is better than that of the core of the grain bulk, and this phenomenon is more significant when there is a radiant heat source outside the silo roof; When the ventilation rate increased from 28. 26 m3/h to 35. 95 m3/h, the temperatures of the outer skin and inner core of the grain bulk with external radiant heat source on the silo top decreased by 1. 56 and 0. 70 ℃, respectively. The temperature of the skin and core of the grain bulk without external radiant heat source on the silo top decreased by 0. 30 and 0. 08 ℃, respectively. In conclusion, increasing the ventilation rate in the working condition with radiant heat source outside the silo roof can improve the local temperature control performance of the grain bulk seepage ventilation and temperature control system. In the actual application process, the system should be operated with low ventilation in daytime to isolate external heat transfer, and with high ventilation at night to reduce the temperature of grain bulk.Keywords：grain bulk;seepage ventilation and temperature control system;ventilation rate;radiant heat source outside the silo roof;temperature control effect23|10|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the survey data of 312 clustered agricultural e-commerce firms in Hubei, Jiangxi and Zhejiang provinces, the relationship between multidimensional proximity and synergetic innovation performance is explored, and the impact of the interaction effect between multidimensional proximity on synergetic innovation performance is investigated. The results show that: 1)Both the social proximity and technological proximity of clustered agricultural e-commerce firms positively affect synergetic innovation performance. There is an inverted U-shaped relationship between geographic proximity and synergetic innovation performance, and a high degree of geographic proximity would bring regional competition, product competition and knowledge spillover, and reduce the synergetic innovation performance. 2)The interaction items of geographic proximity and technological proximity of clustered agricultural e-commerce firms play a positive role in the synergetic innovation performance, presenting a complementary mechanism. The interaction items of social proximity and technological proximity have a negative impact on the synergetic innovation performance, presenting an alternative mechanism. The interaction items of geographic proximity and social proximity have no significant impact on synergetic innovation performance. Therefore, firms should pay attention to the establishment of a benign synergetic innovation relationship with cooperative firms to reduce regional competition and product competition for homogeneous agricultural products in the region. At the same time, the government and relevant organizations should strengthen the technical skills training for agricultural e-commerce firms, and give full play to the role of digital technology in promoting the innovation and development of agricultural e-commerce firms.Keywords：clustered agricultural e-commerce firms;multidimensional proximity;synergetic innovation performance;interaction effect27|11|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To investigate the level and characteristics of the bubble risk in China and the United States cotton futures market, based on the daily price data of China and the United States cotton futures market from 2004 to 2019, the GSADF method is used to measure and compare the bubble risk in China and the United States cotton futures market. The results show that price bubbles exist both in China and the United States cotton futures market, and bubbles are often accompanied by price booms or crashes. Considering the duration, occurrence frequency and occurrence intensity of the bubble, cotton futures market in China presents a higher degree of bubble risk than the United States. There are some differences between the price bubble characteristics of China and the United States cotton futures market. Compared with the United States, bubbles in China cotton futures market occur more frequently, and the price dynamic during the bubble period is lower. Therefore, to ensure the healthy development and enhance the international competitiveness of China cotton futures market, we should accelerate the development of risk management theory and apply it to the cotton futures market, improve the futures market supervision system, and focus on the cultivation of institutional investors in the cotton futures market.Keywords：cotton;futures market;price bubbles;risk measure;right-tailed unit root test23|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
Impact of social network and insurance cognition on farmers' participation in agricultural insurance
Abstract：To investigate the impact of social network and insurance cognition on farmers' participation in agricultural insurance and its mechanism, based on the survey data of some farmers in Wuhan metropolitan area in 2019, this study empirically tested the relationship between these three by using the mediating effect model and Logistic model. The results showed that: Firstly, the social network has no direct significant impact on the participating behavior of farmers in agricultural insurance. Secondly, insurance cognition has a significant positive impact on the agricultural insurance participation behavior of farmers, which can effectively promote their agricultural insurance participation behavior. Thirdly, social network promotes farmers' participation in agricultural insurance by influencing their insurance cognition, and insurance cognition plays a complete mediating role. In conclusion, to promote farmers' wide participation in agricultural insurance, communications between farmers and farmers and village cadres, the propaganda of agricultural insurance, improvement of the agricultural insurance policy system should be strengthened.Keywords：social network;insurance cognition;agricultural insurance;participation in insurance27|10|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
