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- Abstract：To further investigate the effects of conservation tillage(CT)on soil organic carbon(SOC)sequestration, the literatures related to SOC stabilization under CT in the field ecosystem were reviewed. The results indicated that CT could not directly improve the stability of SOC itself. By changing soil physic-chemical properties and SOC molecular structure, CT improved SOC stabilization and sequestration. Future research should focus on: 1)Investigating the relationship between carbon input(sourced from crop straw)and SOC dynamics under CT; 2)Revealing the effects of soil physic-chemical properties on SOC mineralization; 3)Figuring out the effects of conservation tillage on SOC molecule structure and its influence on SOC stabilization.Keywords：conservation tillage;soil organic carbon;stabilization;stability;carbon mineralization10|17|12<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to precisely estimate the production capacity under the latest scientific and technological level, this study builds a measurement model based on the regional test yield of the latest approved varieties of food crops from 2012 to 2016, estimates the breeding production capacity of cultivated land grain in China(excluding Hong Kong, Macao and Taiwan in this study), measures the difference in cultivated land grain yield(yield increase potential)and the development degree of production capacity in China and analyzes the law of inter-provincial differences. The results are as follows: 1)The grain production capacity of cultivated land in China is 8. 46×108 t, the actual output is 5. 48×108 t, the difference is 2. 98×108 t, accounting for 54. 38% of the actual grain production, and the development rate of cultivated land production capacity is 0. 63, which shows that the potential of cultivated land in China can be further developed. 2)China's provinces and cities(such as Heilongjiang Province, Henan Province, Shandong Province, Hebei Province, Jilin Province, Anhui Province, Inner Mongolia Autonomous Region, Jiangsu Province, Hunan Province, Sichuan Province, Liaoning Province, Hubei Province, Yunnan Province, and Jiangxi Province)with large total cultivated land grain production capacity and potential should be taken as key targets for future cultivated land protection and construction, and the quality of cultivated land can be improved through land improvement and cultivation techniques. 3)To develop the productive potential of cultivated land, it is necessary to adjust measures to local conditions so as to realize the balance between increasing grain output and protecting ecology. In Jiangxi Province, Fujian Province and Zhejiang Province, it is suggested to increase the construction of farmland infrastructure and improve the productivity of farmland. In Hebei Province, it is necessary to improve the utilization rate of water resources and to save water and keep grain. In Ningxia Hui Autonomous Region, Gansu Province and Shaanxi Province, it is necessary to coordinate the relationship between agriculture, energy and water resources in order to realize green and sustainable development. In Guangxi Zhuang Autonomous Region, Guizhou Province and Yunnan Province, tea trees and flowers can be planted in gentle slope hilly areas to develop characteristic agriculture by taking advantage of the climate. In Inner Mongolia Autonomous Region, Tibet Autonomous Region and Qinghai Province, over-exploitation of grain production potential is not recommended.Keywords：China;potential grain productivity;regional test yield of certificated grain cultivars;real productivity;yield gap3|12|11<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To study the moisture and thermal effect of the whole plastic film mulching on double ridges of maize in arid land, the relationships between the structure of the ridges and the thermal insulation and water retention performance are studied by numerical simulation method. Four kinds of ridge models, namely T1, T2, T3 and T4 model, are established referring to seedbed construction agronomic requirements of whole plastic-film mulching on double ridges. The process of rainwater infiltration and thermal equilibrium is numerically simulated. Combined with the simulation results, the structure of ridges of the whole plastic film mulching on double ridges and the corresponding supporting machine are optimized. The results of rainwater simulation showed that: Under the same rainfall boundary conditions, the average water content in the T2 model is the highest(water content is 18. 0%), followed by the T4 model(16. 9%), which showed that the ridge structure of T2 model has the best water retention performance. The results of thermal equilibrium simulation showed that under the same temperature boundary condition, the average soil temperature in T4 model is the highest(temperature value is 23. 5 ℃)and the T2 model is the lowest(22. 8 ℃), which showed that the structure of ridge of T4 model has the best thermal insulation performance. However, considering the thermal insulation and water retention, T4 model is the optimal model. In conclusion, The existing structure of the ridge is optimized base on the T4 model: The structure of the ridge arch should be arched, the radius of the large ridge arch is 48 cm, the width is 70 cm and the height is 15 cm, the radius of the small ridge arch is 22 cm, the width is 40 cm and the height is 20 cm; The furrow is trapezoidal, the bottom width is 8-10 cm, and the trench width ratio with large furrow is about 1∶7, the trench width ratio with small furrow is about 1∶4; At the same time, the ridging and spreading machines need to be fitted with a ridge shaping device, and its shape and structural parameters should be matched with the optimized ridge, the width of the walking wheel of the matching direct insert hill-seeder should be less than the width of the furrow(8-10 cm), and the radius of the membrane hole remains at 4-5 cm after sowing.Keywords：whole plastic film mulching on double ridges;moisture and thermal effect;numerical simulation;agronomic optimization2|11|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In this study, the GGE-biplot double plot software was used to analyze the high and stable yield and adaptability of 25 millet varieties such as ‘Yugu 18' in the national millet regional test from 2010 to 2011, and evaluate the adaptability of the target region. The results of two-year regional experiment showed that: 1)the vertical foot of ‘Yugu 18' on AEA axis was the closest to the square, and its high yield was excellent; the projection distance on AEC axis was the shortest, and its stable yield was outstanding. 2)‘Yugu 18' was the closest to the ideal variety, and its comprehensive performance of high and stable yield was better than that of the control variety ‘Jigu 19' and other tested varieties. 3)‘Yugu 18' was the winner of polygon apex, and the most suitable planting area covers most areas of North China summer valley region, which was the most adaptable variety. 4)Compared with the yield of ‘Jigu 19', ‘Yugu 18' had obvious planting advantages in most areas of North China summer valley. It was showed the ideal characteristics of ‘Yugu 18' for high yield, stable yield and wide adaptability in the summer valley region of North China, which provided theoretical basis for the popularization and application of ‘Yugu 18'.Keywords：foxtail millet;gge-biplot;productivity;yield stability;adaptability5|12|9<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore the environmental impacts on indica rice characteristics in three different types of double-season, one-season or indica-japonica cross planting regions. The variations of agronomic and disease resistance characters for 40 indica hybrid rices grown in the three regions in two consecutive years were analyzed. The results showed that the double-season and indica-japonica cross in two regions had significant effects on indica rice agronomic traits(growth duration, plant height, panicle length, effective tiller, total grains per panicle, seed setting rate, 1 000-grain weight and yield), while the traits of one-season region were between them. In the double-season region, panicle neck blast, sheath blight and bacterial blight diseases were severe, and the indica-japonica cross region was severely affected by of endemism panicle neck blight and sheath blight. Based on agronomic and disease characters data by parsimony analysis, it was found that most of the indica hybrid rices with similar agronomic and disease traits showed continuous distribution according to the different planting rice areas, i. e. , 87. 5% aggregation of the indica-japonica cross, 75. 0% aggregation of the one-season and 57. 5% aggregation of the double-season. The probability of indica hybrid rices suitable for planting in both indica-japonica cross and double-season regions was 2. 5%, and in the double-season and one-season regions was 40%.2|11|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore the best seedling-raising model in cold paddy field, taking the high quality japonica rice variety ‘Longjing 31' as the experimental material, and seting up three kinds of raising seedling shed types, such as super shed, standard shed and traditional shed, the effects of different shed types on seedling quality, rice yield and composition factors in cold paddy area were explored. The results showed that the temperature control effect of the two kinds of bigger shed was obviously better than that of the traditional shed, which was suitable for rice growth. The plant height, root length, ear length, root weight and other seedling quality data in super shed were better than those in the other two types of shed. The weak seedling rate in the traditional shed was the highest, and the weak seedling rate in the super shed was the lowest, and the growth period of the seedlings in the two kinds of bigger shed was one week shorter than that in the traditional shed. The number of effective panicles in the super shed and the standard shed were increased by 15. 83% and 4. 80%, respectively. And the total grain number in the super shed and the standard shed were 3. 52 and 1. 47 grains/ear higher than those in the traditional shed respectively. The number of solid grains per panicle in the super shed and the standard shed was 2. 10 and 2. 16 grains/ear higher than that in the traditional shed, respectively; the seed setting rate of rice in the standard shed was 0. 18% higher than that in the traditional shed; the yield of super shed was 3. 21% and 7. 75% higher than that of standard shed and traditional shed, respectively.Keywords：shed;raising seedlings;rice in cold area;rice yield;yield components4|10|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the rice leaves hyperspectral reflectance and incident photosynthetically active radiation(PARin)data, 8 vegetation indices and their products with PARin were used to construct the variety-irrelevant leaf net photosynthetic rate retrieval model, respectively. Two rice varieties, Luoyou 9348 and Fengliangyou 4, were taken as study materials and experiments were conducted under 3 different nitrogen content conditions. The results showed that: 1)Leaf net photosynthetic rate estimation based on chlorophyll-related vegetation indices only was infeasible with R2 below 0. 48; 2)Considering both variety and nitrogen, Chlorophyll Index(CI)multiplied by PARin performed best among the 8 indices with R2 above 0. 75, RMSE no more than 1. 85 μmol/(m2·s)in training and validation set; 3)Considering nitrogen content, the CI models also performed well with R2 of 0. 80 and 0. 89, RMSE of 1. 25 and 1. 37 μmol/(m2·s)in low and high nitrogen content condition in training set, respectively. In conclusion, the model met remote-based retrieval accuracy requirements and could be used for unified retrieval of leaf net photosynthetic rate of rice.Keywords：hyperspectral reflectance;chlorophyll-related vegetation indices;incident photosynthetically active radiation;net photosynthetic rate4|9|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To realize the real-time and lossless monitoring of chlorophyll content in rice leaves by using high precision SPAD remote sensing estimation model, the spectral reflectance of rice leaves under different nitrogen application levels in Northeast China was taken as study object. A SPAD hyperspectral estimation model with different input amounts was constructed by using regression model and BP neural network algorithm. The optimal input quantity and the optimal model were determined by the model precision evaluation index determination coefficient(R2)and the root mean square error(RMSE). The results showed that: 1)The spectral reflectance of different rice varieties was different at booting stage and heading stage; 2)The polynomial model based on DVI(D755, D930)was the most accurate among the regression models. 3)Compared with the regression model, the estimation accuracy of the BP neural network model with single band reflectivity as input at different wavelengths was significantly improved and its R2 was up to 0. 98. The estimation accuracy of BP neural network model was stable when the number of hidden nodes was 7. It was proved that the neural network model was more stable and could be used to invert the relative chlorophyll content by using different band reflectivity as input at visible and near infrared. The results illustrated the spectral response mechanism of different rice varieties in Northeast China, and provided a technical method for the high-precision inversion of SPAD in rice leaves and the regulation of normal growth process of rice in Northeast China.Keywords：rice;hyperspectral;neural network;relative chlorophyll content;vegetation index;first order differential spectroscopy5|8|8<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to establish the rice growth period recognition model independent of time series data, a four-band radiometer(SKYE)was firstly used to collect the daily canopy spectral reflectance during the whole growth stage of rice in this study. Five common machine learning algorithms including K nearest neighbors(KNN), decision trees, support vector machine(SVM), random forests(RF)and gradient boosted decision trees(GBDT)were then used to recognize the rice growth stages. The results showed that the recognition accuracies of RF and KNN were 93. 00% and 91. 92%, respectively. The accuracy of the rest three algorithms were all over 90%. On this basis, when the rice growth stage recognition model was applied to aerial-collected data, KNN algorithm displayed the best applicability with the recognition accuracy of 83. 54%, SVM algorithm showed the worst applicability with the recognition accuracy of 62. 92%, and the recognition accuracy of RF algorithm reached 74. 38%. However, all the five algorithms mistakenly recognized the heading and flowering stages as jointing and booting stages. Here, a KNN algorithm combined with visible atmospherically resistant index(VARI)for rice growth stage recognition was proposed. The recognition accuracy of the model for aerial-collected data was up to 86. 04%, which was more balanced than that using KNN algorithm alone in recognizing different growth stages of rice. The results showed that KNN algorithm combined with VARI had higher accuracy and better generalization ability in recognizing rice growth period.Keywords：paddy rice;growth stage;spectral reflectance;machine learning;vegetation index12|11|8<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to study the characteristics of lily floral scents in different hybrids, Head Space Solid Phase Microextraction(HS-SPME)and Gas Chromatography-Mass Spectrometry(GC-MS)were used to qualitatively and quantitatively analyze the floral volatile components of forty-one varieties of Lilium spp. from twelve lily hybrids. The results revealed that Cineole, (E)-β-ocimene, linalool, and methyl benzoate were the major compounds of the aroma of scented lilies, whereas the quantity and content of volatile compounds of non-scented Asiatic hybrids and Asiatic×Trumpet hybrids were significantly lower than those in scented lilies. The cultivars within the same group were closer in non-metric multidimensional scale maps, and the intersection lily hybrid groups all combined their parents' scent profiles.Keywords：Lilium;aroma;Gas Chromatography-Mass Spectrometry(GC-MS);hybrid groups2|10|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：This study aimed to investigate the polymorphism of Izumo1 gene and its association with litter size in sheep. The DNA sequences of Izumo1 gene in Small Tail Han sheep and Sunite sheep were amplified and sequenced using PCR and direct sequencing, and then analyzed by BLAST. SNPs of Izumo1 gene were screened out by comparing with the previous re-sequencing data of sheep in the laboratory. Sequenom MassARRAY® was used to genotype and the distribution of genotype and allele frequencies of the SNP loci in each group was studied. The results showed: The full lengths DNA sequence of Izumo1 gene were 3 385 bp in Small Tail Han sheep and 3 382 bp in Sunite sheep. Eight SNP loci of Izumo1 gene were screened out. After preliminary screening, the SNP loci with no difference to those of Small Tail Han sheep, Sunite sheep, Tan sheep, Suffolk sheep, Dorper sheep and Prairie Tibetan sheep were excluded. Two loci, g. 54412135A>G and g. 54412107C>A were finally selected. Polymorphism analysis showed that: There were three genotypes of GG, GA and AA in g. 54412135A>G locus of Izumo1 gene in monotocous and polytocous breeds, and G gene was the dominant allele; There were CC and CA genotypes in g. 54412107C>A polytocous breeds, and CC, CA and AA genotypes in monotocous breeds. C gene was the dominant allele, the genotype frequency and allele frequency of this locus were significantly different among high fecundity and low fecundity sheep breeds(P<0. 01). Population genetic analysis showed that: The polymorphism information content(PIC)of g. 54412135A>G polymorphism loci in six breeds belonged to low polymorphism(PIC<0. 25). The g. 54412107C>A polymorphism locus belonged to moderate polymorphism(0. 25Izumo1 gene g. 54412135A>G and the g. 54412107C>A loci and litter size from different parity of Small Tail Han sheep(P>0. 05)by the association analysis.Keywords：sheep;Izumo;1;gene;cloning;polymorphism;SNP;litter size1|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to assess the veterinary drug residues in liquid milk products on the market in China, a total of 150 ultra-heat temperature(UHT)and 50 pasteurized milk samples were collected on 2016 and 2017. ELISA-based visual microarray technology was used to detect veterinary drugs including quinolones, tetracyclines, streptomycin and lincomycin. The results showed that the detection rates of fluoroquinolone, tetracycline, streptomycin and lincomycin were 0%, 0%, 3. 3% and 0% in UHT milk samples, respectively, and their detection rates in pasteurized milk samples were 0%, 0%, 8. 0% and 2. 0%, respectively. The concentrations of fluoroquinolone and tetracycline in all milk samples were lower than the detection limit of the method. The maximum concentrations of streptomycin and lincomycin were 21. 16 and 16. 48 μg/L, respectively, both of which were below the maximum residue limits of European Union, the Codex Alimentarius Commission and China standards. It is concluded that the residual conditions of fluoroquinolone, tetracycline, streptomycin and lincomycin in UHT and pasteurized milk in China are under control and safe.Keywords：UHT sterilized milk;pasteurized milk;veterinary drug;risk assessment2|10|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：This study was designed to investigate the effects of lactic acid bacteria in koumiss(Lactobacillus paracasei subsp. tolerans)on the growth performance, cytokine levels and antioxidant enzyme activities of mice with diarrhea caused by Escherichia coli. Sixty SPF Kunming mice weighing(20+2)g were randomly divided into 6 groups with 10 mice in each group, half male and half female. The diarrhea model of mice was established by intraperitoneal injecting pathogenic E. coli O8 bacterial suspension, and then treated with different concentrations of lactic acid bacteria and antibiotics to test its growth performance, immune organ index and serum immune index and antioxidant index. Four groups were intragastrically administered with 0. 3 mL of live LAB bacterial suspension of 1×106, 1×108, 1×1010 CFU/mL and 0. 15 g/kg of ciprofloxacin hydrochloride, respectively. Mean while, the negative control group was injected with normal saline only without any treatment afterwards, and the normal control group did not give any treatment. The experimental period took 7 days. The results showed that: The intragastrically administered different doses LAB promoted the growth performance of mice(P<0. 05); The spleen index of mice was significantly increased by 1×1010 CFU/mL LAB bacteril suspension(P<0. 05), which was 53. 91% higher than that of negative control group. An upward trend was presented by the thymus index of mice, but the difference is not significant(P>0. 05); There were significant increase in the levels of IL-4, IL-10 and TGF-β, and decrease in the levels of IL-6 and IFN-γ(P<0. 05), and the high dose group of LAB displayed the best effect. There were significantly increase in the activities of CAT, T-AOC, SOD and GSH-Px, significant decrease in the level of MDA content(P<0. 05), and the high dose of LAB group showed optimal effect. In conclusion, the intragastric administration of lactic acid bacteria in diarrhea mice could promote the development of immune organs and regulate serum immunity and antioxidant indexes.Keywords：koumiss;lactic acid bacteria;diarrhea;SPF KM mice;growth performance;cytokines;antioxidant enzymes1|10|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：This study was aimed to investigate the prokaryotic expression and bioinformatics character of Haemonchus contortus GST gene. Using the cDNA of H. contortus as template, specific primers were designed to amplify GST gene. The prokaryotic expression vector pET-30a(+)-GST was constructed and transferred into E. coli BL21(DE3)competent cells, and the expression conditions for the correct recombinant plasmid were optimized. The characteristics of expression protein were analyzed by SDS-PAGE, and the GST protein was analyzed by bioinformatics software. The results showed that the GST fragment of H. contortus was 618 bp. The optimal induction condition of pET-30a(+)-GST recombinant plasmid was 0. 05 mmol/L IPTG at 37 ℃ for 6 h, and the expressed recombinant protein was about 29 ku in the form of inclusion bodies. Bioinformatics analysis showed that the GST formula was C1083H1657N277O294S6, which belonged to hydrophilic protein without signal peptide and transmembrane region. The secondary structure is mainly formed by α-helix, and the potential epitopes are mainly located near 25-48, 55-63, 92-106, 113-124, 139-147, 170-189 and 195-205 amino acids. In this study, the prokaryotic expression system of H. contortus GST gene was constructed, and the GST recombinant protein was stably purified after optimized induction conditions, which provided a theoretical basis for further exploring albendazole resistance mechanism of H. contortus and the biological characteristics of GST-encoded protein.0|12|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to improve the nutritional and physiological function of sturgeon bone collagen, prepare bone collagen polypeptide with high peptide yield and increase the added value of aquatic products, alkaline protease and neutral protease combined enzyme hydrolysis technique was used and the yield of peptide as the study index. The hydrolysis conditions of bone collagen polypeptide were optimized by single factor test and orthogonal design test. At the same time, the growth inhibition effects of squid collagen peptide on the human colorectal cancer cell Caco-2, breast cancer cell MCF-7, liver cancer cell HeGp2, lung cancer cell A549 and cervical cancer cell line HeLa 5 were determined by CCK-8 method. The lung cancer cell A549 with obvious inhibitory effect was then selected as the model to further detect the effect of bone collagen polypeptide on caspase-1, caspase-3 and cell membrane potential of sturgeon, and explore the mechanism of action. The results showed that the optimum enzymatic hydrolysis conditions were as follows: 150 000 U/g of enzyme, the mass ratio of bone meal to water is 1∶25, 5 h of enzymatic hydrolysis time, 50 ℃ of enzymatic hydrolysis temperature, and the ratio of alkaline protease to neutral protease activity is 1∶2. Under this condition, the yield of peptide was(72. 36±2. 33)%. The results of anti-cancer activity assay showed that sturgeon bone collagen polypeptide changed the mitochondrial membrane potential by activating apoptotic protease caspase-1, decreased the membrane potential and induced the increase of caspase-3 activity. The activity of caspase-3 reached 149. 9 IU/μg, which promoted the occurrence of apoptosis and inhibiting cell proliferation. The bone collagen polypeptide of sturgeon showed the ability to inhibit the proliferation of cancer cells and had potential development and application prospects.Keywords：sturgeon cartilage;protease hydrolysis;collagen polypeptid;apoptosis0|12|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To study the effect of different ground forms on gas emission rates of natural ventilation dairy houses in China, 2 typical naturally ventilated dairy buildings were elected as tested house(slatted floor cowshed and solid floor cowshed)in China-Dutch dairy training center, Zhengzhou, Henan Province. The concentrations and emission rates of greenhouse gas(GHG)and NH3 were monitored and analyzed. The results showed that: 1)The ventilation rates of natural ventilation cowsheds calculated by CO2 balance method were related to the production stage of cows. 2)The mass concentrations of CO2, N2O, NH3 and CH4 of slatted floor cowshed were significantly higher than those of solid floor cowshed(P<0. 05). Meanwhile, there was a strong positive correlation between the mass concentration of CO2 and CH4 in the 2 dairy buildings(R2=0. 37-0. 65). 3)The emission rates of NH3 and CH4 of slatted floor cowshed were significantly higher than those of solid floor cowshed. The emission rate of NH3 in slatted floor cowshed and solid floor cowshed were 19. 83 and 11. 45 g/(HPU·d)and the emission rates of CH4 were 117. 22 and 32. 66 g/(HPU·d), respectively. There is no significantly difference of the emission rate of N2O between slatted floor cowshed(0. 12 g/(HPU·d))and solid floor cowshed(0. 11 g/(HPU·d)). 4)Temperature significantly affected the NH3 emission rate in the cowshed, which was positively correlated with ammonia emission(R2=0. 76). In short, the concentration and emission rate of GHG and NH3 in the solid floor cowshed were lower than those in the slatted floor cowshed. It was mainly because the feces cleaning times on solid floor were significantly higher than those in the slatted floor. Therefore, the slatted floor dairy cowshed needs to be improved to increase the removal times of feces and urine in the manure pit and reduce the concentration and emission rate of harmful gas in the cowshed.Keywords：cowshed;slatted floor;solid floor;CO;2;balance method5|10|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To solve the difficulty of cooling and uneven temperature distribution in large-scale glass multi-span greenhouses in China, a positive pressure ventilation cooling system(PPVCS)was designed base on the environment control strategy of the semi-closed greenhouse in Netherlands. The system adopted positive pressure ventilation cooling technology, and used evaporation of wet pad to provide cooling source. Through the analysis and calculation of duct fan and air supply pipe, the whole system was established and tested. The experiment was conducted in Venlo-type greenhouse in Nanhe, Hebei Province. The greenhouse with pad-fan negative pressure cooling system was used as the control to compare the cooling effect with greenhouse with PPVCS. The results showed that: 1)The air velocity of each side hole on each side of the air supply pipe was almost the same, and the uniformity of the air supply was good; 2)The inner temperature of greenhouse with PPVCS was 3. 7 ℃ higher than that of control greenhouse on average, and the difference reached 6. 8 ℃ under extremely high temperature. In Nanhe, which located the south of Hebei Province, the cooling effect of the traditional pad-fan negative pressure cooling system was better than that of the innovative PPVCS. The PPVCS still needs to be improved to adapt China's practical situation.Keywords：multi-span greenhouse;positive pressure ventilation;cooling;tube fan1|11|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to tackle the problem of high damage rate during harvesting, fresh potato was taken as the research object, and the damage volume of potatoes was analyzed by orthogonal experiment with the help of potato impact test-rig. The impact process was then analyzed based on the curve of potato collision acceleration. The initial height and potato mass were selected as experimental factors to investigate the variation of peak collision acceleration with each factor level. Finally, the critical value of impact damage of potato was tested. The results showed that the descending order of the significance of factors on damage volume was the initial height, potato mass, potato temperature and impact materials. The collision between potato and rod experienced four stages: viscoelastic compression, elastic-plastic compression, elastic recovery, and separation from rod. The peak acceleration increased with the increase of initial height and declined with the increment of potato mass. When the temperature of potato was 5, 15 and 23 ℃, the damage thresholds caused by potato conflict with 65Mn steel were 0. 99, 1. 253, 2. 506 m/s and 434. 154, 674. 437, 1 249. 794 m/s2, respectively. The damage thresholds caused by potato conflict with 65Mn-plastic and 65Mn-rubber at 15 ℃ were 2. 506, 2. 344 m/s and 1 589. 528, 1 409. 697 m/s2, respectively.Keywords：potato;damage volume;collision acceleration;damage threshold2|8|14<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：The hot research topics of soil food web were reviewed by bibliometrics, and its research context and the trend of future development from 1989 to 2018 were summarized in this study. The results indicated that biodiversity, carbon and nitrogen cycling were driven by soil food web, and the impacts of management on soil food web were hot topics in the current research. While functional diversity, system stability, and response to global change would be the emerging trends in the research of soil food web.Keywords：bibliometrics;biodiversity;climate change;co-occurring network;functional diversity6|10|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to analyze the meat consumption level and its structural characteristics of both urban and rural residents in China, and judge the future trend of meat consumption, the relevant statistical data such as FAO and statistical yearbook were taken as study material. The price elasticity and income elasticity of the meat consumption demand of urban and rural residents in China were measured by using double logarithmic linear expenditure model and LA/AIDS model(Linear approximated/Almost ideal deal demand system model). The results showed that the meat consumption was increasing, and the gap in meat consumption between urban and rural residents was gradually narrowing. Residents had higher income elasticity of beef and mutton demand, followed by poultry and pork. The income elasticity of rural residents' demand for meat consumption was significantly higher than that of urban residents'. Besides, the demand for beef and mutton in China was sensitive to the changes of beef, mutton and other meat prices. The resident's demand of pork was less sensitive to changes of pork price and other meat prices. In conclusion, the consumption of beef and mutton in China will fluctuate, while the consumption of pork will increase slowly, but the consumption will stabilize.Keywords：meat consumption characteristics;trend judgment;double logarithmic linear expenditure model;LA/AIDS model;Chinese residents1|9|7<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on a micro-survey data of 603 farmers in the main grain producing areas of Hubei and Jiangsu provinces, a binary logistic regression model is used to test the effect of farmers' concurrent business on the farmers' behavior of applying biological pesticides, and the moderating effect of agricultural social service between them is also investigated. The results showed that: 1)The farmers' concurrent business significantly reduces the possibility of farmers applying biological pesticides, and this negative influence increases with the increase of the degree of concurrent business; 2)There is heterogeneity in the moderating effect of agricultural social service on farmers with different types of concurrent business between their behavior of applying biological pesticides. Specifically, for multiple occupations farmers type I, the agricultural machinery employment service has a significant positive moderating effect between the two. However, the financial loan service plays a significant negative regulatory role. For multiple occupations farmers type II, due to the positive moderating effect of agricultural insurance service between the two, the negative effect of multiple occupations farmers type II on the application of biological pesticides to farmers is weakened. Based on the findings, it is proposed that the government should promote the ecological cognition of farmers by popularizing biological pesticides with the help of agricultural technicians, increase the policy support for biological pesticides and increase the direct subsidy for the application of biological pesticides including improving the construction of agricultural social service system, selecting the targeted service objects and providing the targeted service content.Keywords：farmers' concurrent business;biological pesticides;agricultural social service;moderating effect2|11|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to investigate the influence of different social relations on farmers' technology adoption behavior, the influences of the intergenerational effect and the neighborhood effect were discussed by using Logit regression model and coefficient clustering method based on 1 116 household survey data in Hubei Province. The results show that: The intergenerational effect and neighbourhood effect have significant effects on farmers' green production technology adoption behavior. The neighbourhood effect is positive, while the intergenerational effect is negative; Compared with intergenerational effect, the neighbourhood effect has greater impact on farmers' green production technology adoption. Therefore, through targeted propaganda and training, the establishment of science and technology demonstration households and other countermeasures, the traditional agricultural production habits and thinking of our parents could be changed given full play to the role of “skilled” in science and technology demonstration of grain planting, and it will play a positive role in improving farmers' adoption of green production technology.Keywords：farmer;intergenerational effect;neighbourhood effect;green technology1|9|9<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To protect the interests of farmers during land transfer, improve the land transfer market and increase farmers' income, this study builds a principal-agent model to investigate the disputes between the land operator and farmer in the process of farmland transfer, and analyzes the effects of the land transfer scale, incomplete information and high transaction costs. Based on a survey data, the Probit model and the instrument variable estimation method are used to analyze the impact of various influencing factors on land transfer disputes. The results show that the larger the scale of land transfer, the higher the probability of disputes. The more complete the market information, the lower the transaction cost is. The less government intervention, the fewer disputes are. Therefore, it is feasible to reduce the land transfer disputes by promoting moderate scale operations, improving the completeness of land transfer information, reducing transaction costs and protecting the autonomy of farmers' land transfer.Keywords：farmland transfer;dispute;principal-agent model;Probit model;instrumental variable0|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to understand the dynamic evolution characteristics of China's leisure agriculture development efficiency, the leisure agriculture data of 30 provinces(municipalities and autonomous regions, the statistical data of Tibet autonomous region, Hong Kong, Macao and Taiwan are not included, the same as below)from 2008 to 2016 were analyzed. Heterogeneous environmental variables were introduced into the efficiency measurement and three-stage DEA was used to evaluate the development efficiency of China's leisure agriculture. The convergence of the leisure agriculture efficiency in China was verified by PS convergence test. The results showed that: 1)There were significant differences in the efficiency of leisure agriculture development in 30 provinces(municipalities and autonomous regions). The introduction of environmental heterogeneity variables has revised the input-output variables, and the differences in inter-provincial efficiency were more obvious; 2)There was no convergence in the overall development efficiency of leisure agriculture in China, but there was club convergence effect, and included 7 types of convergence. There were bigger differences between different types of relative transfer paths. The following policy recommendations were proposed based on the research: Transforming the development direction of leisure agriculture from scale expansion to structural upgrading; Implementing differentiated efficiency improvement strategies and narrowing down regional efficiency gaps; Strengthening regional exchanges and promoting regional leisure agriculture collaboration.Keywords：leisure agriculture;development efficiency;three-stage DEA;convergence3|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
