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- Abstract：To quantitively evaluate the effect of crop residue energy utilization on the ecological environment, this study analyzes and compares the eco-efficiency of crop residue energy utilization in 31 provinces and cities in China from 2011 to 2018 by using the data envelopment analysis(DEA)method. The results show that the eco-efficiency values of crop residue energy utilization in Jiangsu, Fujian, Hainan, Guangxi, Sichuan, Jilin and Heilongjiang provinces are equal to 1, indicating that the energy utilization of crop residue in these 8 regions has a positive effect on the ecological environment. In addition, reasons for the low ecological efficiency of straw energy utilization in these provinces are identified, which are due to the high redundancy of input indicators and the low product yield. High ecological efficiency of straw energy utilization in China could be achieved by improving both the level of regional development and the level of energy-using processes so as to fulfill the goal of increasing biomass production while reducing resource input.Keywords：crop residue;energy utilization;eco-efficiency;DEA analysis;redundancy rate8|7|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to clarify the effects of plant growth regulator on the growth and yield of mung bean, ‘Lvfeng 2'variety was used as the material. The effects of spraying water(CK), spraying S3307 and spraying DTA-6 on the accumulation of dry matter in the above-ground parts of mung bean from flowering to maturity were studied. The distribution and transportation ratio of dry matter among parts provided further research. The results show that: DTA-6 and S3307 significantly prolonged the period of the dry matter accumulation and increased the dry matter accumulation of the above-ground. The distribution of dry matter among the leaves, pods and seeds was significantly enhanced by spraying PGR on the leaf surface at the beginning of flowering period. The transportation ratio of main stem leaves was improved by the treatment of S3307, however, the transportation ratio of stalks was improved by the treatment of DTA-6. Both the treatments of S3307 and DTA-6 further promoted the effective transfer of the dry matter from “source” to “sink”. The yield of S3307 and DTA-6 was higher than that of CK. In conclusion, according to the comprehensive analysis in this study, spraying 60 mg/L S3307 or 50 mg/L DTA-6 on the leaves at the beginning of flowering period can significantly increase the dry matter accumulation of mung bean, increase the distribution of dry matter to seeds, and then increase the yield of mung bean.Keywords：mung bean;plant growth regulator(PGR);accumulation of dry matter;transportation of dry matter;yield6|9|16<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To study the response pattern of stress resistance gene of Hordeum vulgare var nudum seedlings to cobalt stress, the phenylalanine ammonia-lyase(PAL)gene was cloned and the expression patterns of related stress resistance genes were analyzed. In this study, H. vulgare var nudum ‘Kunlun 15' was used as the material to clone the cDNA sequence of PAL, named HvPAL(GenBank No. MK695675). The length of PAL gene cDNA is 2 142 bp, which contains a open reading frame(ORF)encoding 713 amino acids. The bioinformatics analysis show that there are three highly conserved domains in the amino acid sequence of HvPAL, including the conserved amino acid sequence, which has high homology(90%)with that of barley and wheat. The molecular phylogenetic tree is constructed based on PAL protein sequence, and H. vulgare var nudum and Gramineae were clustered together. The expression of related genes in H. vulgare var nudum seedlings under CoCl2 stress was analyzed by real-time fluorescence quantitative PCR. Compared with the control, the expression of SOD gene was the highest under 70 mg/L Co2+ treatment(P<0. 05), the expression levels of PAL, GSH, and P5CS genes reached the maximum under 150 mg/L Co2+ treatment(P<0. 05), and the expression level of POD gene was the highest under 200 mg/L Co2+ treatment(P<0. 05). In conclusion, the POD, PAL, GSH, P5CS and SOD genes were coexpressed in seedlings to resist and adapt to Co2+ stress.2|9|3<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Phalaenopsis spp. and Rhynchostylis retusa were selected for intergeneric hybridization study. A total of 141 progenies were obtained from 36 cross combinations. The sterile sowing technique and character investigation were used to analyze the seeds and hybrid progenies. The results showed that: 1)Among 36 cross combinations, only 12 cross combinations obtained 20 capsules and the fruit-setting rate was 11. 1%. 2)Of the 12 combinations with the fruit-settings, only one combination PR01 seeds germinated on the induction medium, and the rest of 11 combinations could not germinate, which could be due to insufficient development of capuls and failure during embryo formation. 3)The seeds of PR01 could germinate on the induction medium of M1, M2 and M3. BA 2. 0-3. 0 mg/L and Ad 2. 0-3. 0 mg/L were beneficial to protocorm proliferation and the rooting medium T2 was suitable for the rooting of PR01. 4)The quantity and pseudo-quality traits of the hybrid F1 traits displayed were mostly somewhere in between both parents. The hybrid F1 generation inherited the characteristics of both parents. However, their flowering time was inconsistent and the flowering rate was 15. 6% after 3 years of planting, whereas both parents all blossomed at the same time. In conclusion, the plants and flowering traits of PR01 generally tend to be Phalaenopsis.5|27|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to compare the differences of volatile components in flowers of different Phalaenopsis germplasm resources and screen the main aroma components, two Phalaenopsis flowers with floral scent(floral-scented group)and two germplasm resources(non-fragrant group)without floral scent were used as test materials. The volatile components of flowers were determined by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry(HS-SPME-GC-MS). Chroma TOF software and NIST mass spectrometry database were used to identify the volatile components and determine their contents. The main volatile components aroma intensity values(OAVs)were calculated and the aroma quality was evaluated. The results showed that: 1)Total of 365 volatiles were identified from the 4 Phalaenopsis flowers, and the highest contents in the floral-scented group were linalool, geraniol and(2E, 6Z)-nona-2, 6-dienal, while the highest contents in the non-fragrant group were 2-hexenal, (2E, 6Z)-nona-2, 6-dienal and hexanal; 2)Floral, green and fatty were the main aroma characteristics of the floral-scented group samples, and green, fatty and citrus were the main aroma characteristics of the non-fragrant group samples. 3)The main aroma components in Phalaenopsis flowers were linalool and geraniol, and their contents were the decisive factors for whether the flowers had floral scent or not. The flowers without floral scent also had micro volatilization of the main aroma components, which did not reach the olfactory threshold.Keywords：Phalaenopsis;volatile components;odor-activity values(OAVs);aroma quality8|11|7<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to solve the problems existed in the traditional identification methods during the process of intelligent management of pigs, for example, ear tags are easy to fall off and pigs are easy to be infected, a non-invasive method based on the improved YOLOv3 model was adopted to study the multi-individual identification of pigs. Based on the original YOLOv3 model, this study introduced DenseBlock in Darknet53 feature extractor and combined it with down-sampling layer to form a new backbone, then added improved SPP unit in YOLOv3 detector, and finally constructed YOLOv3_DB_SPP network. The pig face data sets were divided into 10 categories. After data augmentation, there were 8 512 samples in total, and the ratio of training set to test set was about 9∶1. The results showed that: 1)In each classification probability threshold, the mean average precision of YOLOv3_DB_SPP detected on pig face data set was higher than that of YOLOv3 model; 2)When the IOU threshold was 0. 5 and classification probability threshold was 0. 1, the mean Average Precision of YOLOv3_DB_SPP was 9. 87% higher than that of YOLOv3; 3)When the YOLOv3_DB_SPP model detected remote and occluded small targets, the average precision was higher than YOLOv3. The experiment proves that YOLOv3_DB_SPP model can improve the feature extraction capability of the basic feature extractor and the accuracy of the detector.Keywords：pig face recognition;YOLOv3;DenseNet;SPP3|9|11<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to explore the impact of cow body condition on milk production and subclinical ketosis, the experimental data was collected at 3 large-scale breeding farms in Heilongjiang Province at 10, 20 and 60 days after delivery of dairy cows. According to the domestic and foreign body condition scorer(BCS)standards, cows were divided into low BCS group(BCS≤3. 00), medium BCS group(3. 25≤BCS≤3. 50)and high BCS group(BCS≥3. 75). Then daily milk production statistics and β-hydroxybutyric acid(BHBA)determination were carried out. The results showed that: 1)Different body conditions had a greater impact on milk production. During 10-20 d, it displayed a very significant(P<0. 01)correlation with milk production in both low and medium BCS groups. 2)The risk of SCK in low and high BCS groups was 2 to 6 times higher than that in medium BCS group(P<0. 01). In conclusion, different body conditions had different effects on milk yield and SCK of cows. When BCS of postpartum cows were 3. 25-3. 50, their milk performance was better and the SCK incidence rate was lower.Keywords：dairy cow;body condition;milk production;subclinical ketosis7|9|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to understand the species and prevalence of bacteria in mastitc milk samples and environment in a dairy farm in Tianjin, six cows with mastitis were screened by California mastitis test(CMT)method. Bacteria were isolated and identified from mastitc milk samples, cattle living environment, livestock house milk hall samples by traditional culture method. The results showed that 217 strains were isolated and identified from mastitc milk samples and environmental samples. The dominant bacteria were Bacillus(146/217 strains, 67. 28%), mastitc milk accounted for 25%(3/12), barn samples accounted for 47. 87%(45/94), and dairy samples accounted for 88. 29%(98/111). A total of 4 strains of Staphylococcus were identified in mastitc milk samples, 10 strains of Staphylococcus and 8 strains of Enterobacter were identified in livestock barn samples, 1 Klebsiella strain bacteria was identified in the new litter and feed samples, and 3 stains of BMV7 were isolated and identified from the sample of front medicine bath and back medicine bath cup. In summary, this study explored the main prevalent microbial species in a dairy farm in Tianjin, and proposed the weaknesses of the health management and control of the farm, and put suggestions and opinions for dairy cow mastitis prevention and control and health management, and laid the foundation for further traceability of mastitis pathogens.Keywords：dairy cattle;mastitic milk;environment;bacteria;isolation;identification1|8|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：To explore whether propionate has effect on the expressions of key genes in the gluconeogenesis pathway in goat intestinal epithelial cells, the experiment was divided into two parts: The first part was divided into four groups. Firstly, 0, 0. 75, 1. 50 and 3. 00 mmol/L propionate were respectively added to culture GIEC for 6 hours. Then the total RNA was extracted from the collected cells. The second part was divided into two groups. GIEC was cultured with 0 and 3. 00 mmol/L propionate, respectively. The total RNA was extracted from the collected cells at 3, 6, 12 and 24 h after culturing. qRT-PCR was employed for analysis of mRNA expression of key genes in the gluconeogenesis pathway. The results showed that there was no significant difference in the mRNA expression levels of PC, FBP1 and PGC1A with the addition of 0. 75 and 1. 50 mmol/L propionate groups(P>0. 05). The 1. 50 mmol/L propionate significantly increased PCK2 mRNA expression(P<0. 05), while 3. 00 mmol/L propionate significantly increased the mRNA expression of PCK2 and PGC1A (P<0. 05)and upregulated the mRNA expression of PC and FBP1, but there was no difference(P>0. 05). Compared with untreated group, 3. 00 mmol/L propionate significantly increased the mRNA expression of PCK2 and PGC1A at 6 h(P<0. 01), and the mRNA expression of PC and FBP1 was also increased(P>0. 05). There was no effect on the key genes of gluconeogenesis pathway between 12 and 24 h(P>0. 05). In conclusion, propionate can induce mRNA expression of key genes in the gluconeogenesis pathway in goat intestinal epithelial cells, and PCK2 plays a key role in the gluconeogenesis pathway.Keywords：propionate;intestinal epithelial cells;gluconeogenesis;glucose4|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to investigate the effects of house feeding on the physiological and mental health of pregnant ewes, a monitoring device of ewe prenatal movement behavior based on three-axis acceleration sensor MPU6050 was designed, and 37 adult Small-Tail Han ewes' prenatal movement behaviors(standing, walking, lying and digging)were classified and identified. To solve the difficulty in identifying two static behaviors of ewe' lying and standing behavior, the K-means clustering algorithm was adopted to identify the ewes' lying behavior. On the basis of the recognition results, the other three kinds of behavior data were corrected, filtered and windowed by MATLAB software, and 19 dimensional feature values of ewes' movement data were extracted. The principal component analysis method was applied to obtain the six components whose cumulative contribution rate was up to 95%. BP neural network algorithm was then used to identify the other three kinds of movement behaviors(standing, walking and digging). The results showed that the designed ewes' prenatal movement behavior recognition algorithm could recognize ewes' prenatal lying behavior with the recognition rate of 99. 2%. The recognition rates of standing, walking and digging were 85. 7%, 88. 9%, and 80. 0%, respectively, which could satisfy the requirements of ewes' behavior recognition. The recognition rate of the algorithm was improved by 9. 9% after the processing of PCA, and the recognition effect was improved significantly.Keywords：ewes;house feeding;prenatal behavior;clustering algorithm;neural network;behavior recognition2|8|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to understand the latest research status of alternative splicing regulation process of animal muscle growth and development, the molecular mechanism of protein diversity regulation, human and animal muscle development alternative splicing and the research progress of alternative splicing data quantitative method were summarized based on the publications of muscle growth and development of alternative splicing regulation of human, mouse and other animals. The results showed that muscle was one of the tissues with the highest level of tissue specificity and conservative alternative splicing; The occurrence of alternative splicing was not consistent with fetal development, but concentrated in the first two weeks after birth; The intron retention alternative splicing pattern of cattle muscle was the most, followed by the number of exon skipping; Alternative 3'splice site was the most common type of splicing in the muscle development of pig and chicken. With the progress of sequencing technology, the analysis method of alternative splicing was developed into the Pacific biosciences and the Oxford Nanopore technology from low flux(qRT-PCR and ESTs), high noise(EST, Gene Chip)analysis method. These two representatives of the third-generation sequencing methods have successfully identified many good characteristics of the transcript and alternative splicing. In conclusion, with the development and update of sequencing methods and analysis software, the research on alternative splicing of animal muscle development will lay a foundation for revealing the development mechanism of muscle.Keywords：alternative splicing;protein diversity;muscle development7|9|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to determine the optimum side vent height of the greenhouse under different environmental requirements such as cooling, dehumidification and ventilation, four heights of side vents, 40, 60, 80 and 100 cm, were designed in greenhouse in Yangling, Shaanxi Province. The experimental measurement and computational fluid dynamics simulation technology were applied to research the effects of vent height on variation and distribution of indoor flow field, temperature, relative humidity. The model was verified by actual measurement. The results show that: The simulation values of model are consistent with the variation trend of measured values, and the average relative errors are 1. 2% and 2. 0%, respectively; The numerical simulation results show the average indoor wind speed with different vent heights are ranked from high to low is 60, 40, 80 and 100 cm; The instantaneous change rate of temperature and humidity increases first and then decreases with the increase of vent height; The side vent of 100 cm is the best in distribution uniformity, followed by 60 cm, the variation coefficient of temperature and humidity at 27 sites was only 1. 1% and 3. 0% higher than that of 100 cm; Considering the cooling and dehumidification requirements of ventilation, indoor air flow is active when the side vent is 60 cm from the ground, which is suitable for cooling and dehumidification in summer; Moreover, the vent height can be increased on the basis of 60 cm to slow down the cooling speed while ensuring the dehumidification effect, which is suitable for the heat preservation and moisture drainage in winter; Reducing the vent height can slow down the rate of environment change, which is suitable for ventilation demand in extreme weather.Keywords：plastic greenhouse;ventilation;flow field;air temperature;relative humidity;computational fluid mechanics4|9|9<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In view of the complex deformation and serious instability of purlin in greenhouse structure, the mechanical properties of open section purlin in greenhouse structure was studied. The open section purlin was taken as pressure-bending-torsion bar due to the complexity of mechanical deformation. Firstly, the second order internal force was discussed and equilibrium equations of bar microsegment isolator were established by considering the pressure-bending-torsion coupling, constraint warping and shear deformation. The displacement control equations in regard to both torsion angle and deflection were then deduced by combining with physical equations and geometric equations, and the geometric nonlinear calculation model for displacement and internal force of bar under the pressure-bending-torsion coupling was obtained. At the same time, a calculation procedure was put forward, the deformation, displacement and internal force of the bar with open section under concentrated torque, distributed torque, compression-torsion load, bending-torsion load and pressure-bending-torsion load were calculated, respectively. The calculation values were compared with the theoretical values to verify the applicability and accuracy of the model. In conclusion, the nonlinear static model in this study is suitable for the calculation of displacement, deformation and internal force of open section urline in greenhouse structure under any load condition.Keywords：greenhouse structure;purline;open section;pressure-bending-torsion coupling;geometric nonlinearity;static method2|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to ensure China's food security, well-facilitated farmland construction for increasing grain yield has become one of China's national strategies. The accurate estimation of well-facilitated farmland demand is necessary for scientific planning of construction in the next 10 years(2020-2030). This study aimed to predict the well-facilitated farmland construction area by using the flow statistics method based on the self-sufficiency rates of staple food grains including(grain, cereal, rice and wheat)in China. The trade flow of grain, cereal, rice and wheat was analyzed. The data were collected from China's National Bureau of Statistics, the General Administration of Customs and the United States Department of Agriculture. Self-sufficiency rates of grain, cereal, rice and wheat were calculated. Regression models were established to forecast the domestic utilization of grain, cereal, rice and wheat in 2020, 2025 and 2030, respectively. Before model establishment, data of rice and wheat(RW)were added up and the time series of grain, cereal and RW during the period of 1997-2018 were tested whether they are stationary or not. The non-stationary data were used for model establishment. The restrictions of the area of well-facilitated farmland and the fresh water in each province were analyzed and the grain production capacity of well-facilitated farmland per unit area in different regions was calculated. The multiple cropping index was calculated according to the proportion of farmland area in different cropping system zone. Based on these indexes, the areas of well-facilitated farmland needed to ensure food security in China in the next 10 years in different self-sufficiency rate of grain were estimated. The results showed that: 1)the self-sufficiency rates of grain, cereal, rice and wheat in China from 1997 to 2018 were 86. 24%-118. 15%, 88. 67%-121. 67% and 84. 25%-123. 98%, respectively. Since 2006, China had kept the strategic bottom line of “basic self-sufficiency of cereal and absolute security of rice and wheat”, but the self-sufficiency rate of grain was relatively lower than the 95% required by “National Food Security In the Long-term Planning Outline”. It was necessary to further enhance the national food security capability and the construction of well-facilitated farmland is an important strategy to ensure food security; 2)Based on the models, the grain domestic utilization in 2020, 2025 and 2030 would reach 723. 18, 726. 73 and 727. 24 million tons, the cereal domestic utilization would be 678. 98, 682. 51 and 683. 01 million tons, and the rice and wheat domestic utilization would be 328. 11, 338. 63 and 349. 14 million tons, respectively. The statistical test and verification proved that the prediction results were reliable; 3)Based on the meeting to food demand by the increase of well-facilitated farmland, the well-facilitated farmland constructed by 2018 could meet the demand under the condition of 90% self-sufficiency rate. Because the current self-sufficiency rate is under the condition of 95%, more than 68. 44, 71. 25 and 71. 65 million hectares well-facilitated farmland should be built by 2020, 2025 and 2030, respectively. In conclusion, this study can provide reference to plan the schedule of well-facilitated farmland construction in the future.Keywords：food security;well-facilitated farmland;self-sufficiency rate;cereal;prediction model3|8|7<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Aiming at the problem of farmland soil antibiotics ecological risk caused by livestock and poultry manure during manure application, the flow of antibiotics in the crop-farm animal production system was analyzed. Based on farmland soil antibiotics ecological risk values, an estimation model on farmland carrying capacity for livestock and poultry manure was established. The crop-farm animal production systems in Heilongjiang Land Reclamation Area(HLRA)and Xinjiang Production and Construction Corps(XPCC)were selected as the study object. The corresponding farmland carrying capacity for livestock and poultry manure was calculated and obtained. The results showed that: 1)The carrying capacities of swine equivalent in HLRA and XPCC were 58 and 66, respectively. 2)Sulfadiazine(SD)and enrofloxacin(ENR)should be taken into account firstly to prevent farmland soil antibiotics' ecological risk in HLRA and XPCC during the manure application. Therefore, local standards were established to control antibiotics in manure, especially high ecological risk antibiotics. Secondly, to ensure the livestock's healthy growth, it was recommended to pay attention to the environmental regulation of breeding houses. Finally, the manure treatment techniques needed to be optimized and related equipment were needed.Keywords：farmland carrying capacity for livestock and poultry manure;antibiotics;ecological risk values;environmental capacity3|14|5<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to scientifically and rationally determine the ecological protection red line and effectively identify the key indicators that affect the importance of ecological protection in Kunming, this study was based on the analysis of the natural characteristics of Kunming, an evaluation index system for ecological protection was built through the evaluation of ecosystem function importance and ecological sensitivity. The importance of ecological protection in Kunming in 2017 was evaluated quantitatively and graded by means of factor space overlay mapping and maximum value. The results showed that: 1)The area in the highest and higher importance level of ecological protection in Kunming was 6 324. 96 km2, accounting for 30. 1%. The area in the general importance level was 9 962. 04 km2, accounting for 47. 41%. The area in the lower importance level was 4 690 km2, accounting for 22. 32%. 2)The spatial differentiation of the importance of ecological protection in Kunming was evident in the following: the areas of the highest and higher importance were mainly distributed in the northern mountain area, Dianchi Lake Basin and stone rocky desertification district; The areas of lower importance were mainly distributed in southern districts such as Anning City, Chenggong District and Jinning District. 3)The importance of biodiversity conservation was the most essential factor of ecological importance in Kunming, it is showed that biodiversity conservation function was the key of ecological protection. The research results provided scientific references for optimizing the ecological protection red line, developing and classifying ecological protect zone and constructing the green ecological environment protection barrier in Kunming.Keywords：spatial planning;importance of ecosystem service;ecological sensitivity;Kunming City, Yunnan Province4|8|10<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Forest land plays an important role in the construction of national ecological civilization. In view of the protection and construction of forest land, Heilongjiang Province, Guangxi Zhuang Autonomous Region and Yunnan Province with the highest proportion of forest land area in the three major forest regions of China were selected. Based on the remote sensing monitoring data of land use and socio-economic data, the spatial-temporal changes analysis and driving force analysis of forest land with long time series at pixel scale were studied by using land use change dynamics, cluster analysis, nuclear density estimation and principal component analysis. The results showed that: 1)From 1980 to 2015, the forest land area of Heilongjiang, Guangxi and Yunnan all decreased, and the area of Heilongjiang Province decreased the most. 2)The transformation of forest land in three provinces was concentrated between forest land, cultivated land and grass land. Among the conversion of second classification, the change of forest land was the most obvious. 3)There was no significant fluctuation in the degree of spatial distribution of forest land in three provinces over the past 35 years, and the forest land degradation area was concentrated and small in scope. 4)The urbanization rate, transportation development level and economic development level were the main driving forces affecting the change of forest. This study provided reference for the monitoring, management and sustainable development of forest resources.Keywords：forest land;spatial and temporal change;nuclear density estimation;driving force4|9|4<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to evaluate the effects of urbanization level on agricultural carbon emissions, a PVAR model is constructed. The impact of urbanization on agricultural carbon emissions in Anhui Province is evaluated from the perspectives of population urbanization and land urbanization using the method of GMM, based on the panel data of 16 cities in Anhui Province from 2000 to 2017. Then the impulse response function and variance decomposition method are adopted to analyze the regional differences of urbanization on agricultural emissions in the southern, central and northern Anhui. The results are as following: 1)The impact of population urbanization and land urbanization on agricultural carbon emissions is different in size and direction, and there are significant regional differences. Population urbanization and land urbanization have negative and positive impact on agricultural carbon emissions, respectively. The impact of population urbanization in southern Anhui is larger, which lasts longer and increases more rapidly than that in other regions, and the land urbanization accelerates the population urbanization. 2)There are regional differences in the contribution of population urbanization and land urbanization to agricultural carbon emissions. The population urbanization in central Anhui contributed the most(9. 4%), while the land urbanization in northern Anhui contributed the most(25. 0%).Keywords：urbanization;agricultural carbon emissions;PVAR model;regional differences;Anhui Province10|9|9<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the meteorological data of three northeast provinces in China from 1961 to 2015, this study analyzed Standardized Precipitation Evapotranspiration Index in four periods(snowy season, rainy season, growing season, annual period), and used HP filter method to capture four crop meteorological yields(rice, corn, soybean, wheat)from 1992 to 2015, then transformed them to standardized yield residuals series(Yr). Furthermore, the effects of SPEI in different periods on meteorological yields of crops in Northeast China were analyzed. The results indicated: 1)There was a significant correlation between SPEI in snowy period and standardized yield residuals series Yr, especially in Liaoning Province; 2)It suggested that different response of crop yields to SPEI depended on regions, periods and crop species. A negative correlation was discovered between rice meteorological yield and SPEI in different periods, soybean meteorological yield first increased and then decreased as SPEI increased in growing period or yearly. Under the background of general drought trend in Northeast China, the impacts of SPEI in different periods on crop yield were not uniform, which showed that there were regional and seasonal differences in response of crop yields to meteorological drought in Northeast China. Therefore, to guide future agricultural production thoroughly, it is necessary to consider not only large-scale climate change but also local climate characteristics, especially the drought in non-growing season.Keywords：standardized precipitation evapotranspiration index;food crops;drought;yield;standardized yield residuals6|9|12<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the fact that the share of agricultural factor income is quite different across space and time, a spatio-temporal heterogeneous elasticity production function model was adopted to analyze the relationship among the input of agricultural factors, technological progress and economic growth in different regions in China since the reform and opening up using input and output data of agricultural key factors in 31 provinces in China(The data do not include those of Hong Kong Macao and Taiwan regions). The results demonstrate: The agricultural factor input was featured by a reduction in labor force and increase in capital stock, and there were obvious spatial heterogeneities in the input of agricultural factors among different regions. The total factor productivity(TFP)increased rapidly in the early stages of reform and opening up, and the growth rate declined significantly in recent years. The average annual growth rate of TFP reached 2. 4% in East China, higher than 1. 6% in Central China and 1. 6% in West China. In conclusion, the spatial and temporal difference in the Chinese agricultural production mode requires that more attention be paid to the development of regional agricultural comparative advantage in the future. While promoting the deepening of agricultural capital, the growth of agricultural total factor productivity from the perspective of infrastructure and institutional design should be accelerated.0|8|1<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to investigate the effect of the Belt and Road Initiative(BRI)on China's agricultural trade, a computable partial equilibrium GSIM model of agricultural trade was constructed. Based on the relevant trade and economic data between 2005 and 2018, the relevant parameters and calibration values were calculated and the border effect of bilateral agricultural products trade between China and the Belt and Road countries was measured. Simulation analysis was also conducted under different scenarios to analyze the impact of the BRI on China's agricultural trade. The results showed that: Compared to the data before 2013, the border effect of agricultural products trade between China and the Belt and Road countries fell by 48. 5%, which meant the BRI significantly reduced the trade barriers, and effectively promoted the bilateral agricultural trade. There were certain differences among different domestic regions, and between unilateral and bilateral effects. The reduction of border effect in the central and western areas was more than that in other areas, and the reduction of import border effect was more than that of export. With the implementation and improvement of the BRI in the future, the decline of trade cost and local preferences and the agricultural technology progress will further reduce the border effect. The gap between regional trade levels will be gradually reduced, the agricultural trade activities will become more active, and there will be a continuous growth of agricultural trade between China and the Belt and Road countries.Keywords：the Belt and Road Initiative;agricultural trade;GSIM model;border effect4|8|0<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on the improved cobweb model, this study analyzed the mechanism of the effect of the temporary purchase and storage policy exit on the price discovery function in China's maize futures and spot markets. The rolling cointegration, VECM, BEKK-GARCH and IS models were used to explore the specific effect of this policy and it's reform on the price discovery function in China's maize futures and spot markets during 2009 to 2019. The results showed that: 1)There was a mutual guiding relationship between China's maize futures and spot market prices. 2)The BEKK-GARCH model displayed that there was a one-way volatility spillover effect between maize spot price and futures price in China, the exit temporary purchase and storage policy made the relationship between futures and spot prices becoming closer. 3)The IS model further revealed that the temporary purchase and storage policy weakened the price discovery function in China's maize futures. With the exit of policies, China's maize futures market regained its dominant position in the price discovery process. 4)From a regional perspective, after the withdrawal of the temporary purchase and storage policy, the price discovery function of the maize futures market in various regions of China was improved to varying degrees, as the main implementation area of the policy, the northeast maize futures price discovery function has been improved significantly. The market-oriented reform of China's maize temporary purchase and storage policy achieved remarkable results, which provided experience for the follow-up reform of the minimum purchase price policy of rice and wheat.Keywords：temporary purchase and storage policy;futures and spot markets;price discovery;IS model;maize1|8|2<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：In order to understand the effects of farmers' adaptation to climate change on the agricultural output, based on the field survey data of farmers in major grain producing provinces such as Hebei and Henan, a treatment effects model is adopted to empirically analyze the effects of farmers' adaptive behaviors to climate change on grain yield. The results show that: 1)In the impacts of climate change, nearly 80% of farmers have taken corresponding measures, and farmers tend to adopt low-cost adaptive measures. 2)Whether or not the farmers take adaptive measures is affected by internal and external factors. Temperature and precipitation have significant positive and negative effects on farmers' adaptive behavior in turn. Planting area has a positive impact on farmers' adaptive behavior. 3)Farmers' adaptation to climate change has a significant positive impact on the grain yield per unit area. Compared with the farmers without adaptive behaviors, the grain yield per unit area of farmers who take measures is higher.Keywords：climate change;adaptive behavior;yield;treatment effects model6|10|21<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
- Abstract：Based on 614 survey data in the Yangtze River Basin, the relationship between social capital, ecological cognition and rational fertilization behavior was explored, and a multi-group analysis was conducted with part-time employment experience and family income as the moderating variables. The results showed that: 1)The proportion of reasonable fertilization was 57. 82%. 2)The social network and ecological cognition had a direct incentive effect on rational fertilization behavior, while social trust and social norms displayed a direct positive effect on ecological cognition. At the same time, under the mechanism of ecological cognition, social trust and social norms also had indirect incentive effect on rational fertilization behavior. 3)The social network and ecological cognition of low-income farmers with no part-time experience had more significant influence on rational fertilization behavior. In conclusion, to enhance their ecological cognition and promote rational fertilization behavior, training on the rice and shrimp co-breeding mode, enriching the village collective organization activities and encouraging rice and shrimp farmers to learn from each other should be strengthened.Keywords：social capital;ecological cognition;rational fertilization behavior;rice and shrimp co-cultivation model;structural equation model0|8|8<HTML><L-PDF> <Meta-XML>Updated：2024-02-27
