Abstract:Objective To investigate the effects of calcium chloride supplementation in drinking water on fat deposition and intestinal flora in mice fed high-fat diet, and provide a theoretical basis for improving carcass characteristics of animals and human health.Method Twenty-seven 4-week-old C57BL male mice were divided into two groups including a high-fat diet (HFD) group and a group with HFD+calcium chloride supplementation in drinking water. The experiment was conducted for 13 weeks. The body weight of mouse was measured weekly. The body fat content of mouse was determined at the end of the experiment. After mice were sacrificed, the subcutaneous fat and epididymal fat of mice were collected and weighed. Mouse feces were collected during 10-12 weeks for high-throughput sequencing of 16S rRNA and the effects on intestinal flora were analyzed.Result Calcium chloride supplementation in drinking water significantly reduced the body weight, body fat content, subcutaneous fat index and epididymal fat index of mice, and compared with HFD group these indexes were reduced by 12.85%, 32.69%, 26.65% and 18.60%, respectively. Meanwhile, calcium chloride supplementation in drinking water increased the community diversity and bacterial abundance in mouse fecal samples. At the phylum level, calcium chloride supplementation had no effect on the abundance of Bacteroidetes, Firmicutes, Proteobacteria, Deferribacteres, Actinobacteria and Tenericumes. At the class level, compared with the HFD group, calcium chloride supplementation in drinking water significantly reduced the relative abundance of Erysipelotrichia and Actinobacteria, whereas significantly increased the relative abundance of Clostridia.Conclusion Calcium chloride supplementation in drinking water reduces the body weight and body fat content of mouse fed HFD, which might be associated with the increase in bacterial diversity and abundance of some specific bacteria in mouse feces.

Abstract:Objective To study the effects of feeding the diets at different protein levels on the structure and number of cecal microflora in goslings.Method Seventy-two one-day-old geese were randomly divided into three groups, including group A, B and C fed with diets containing 16%, 20% and 24% crude protein, respectively. On the 14th day, the cecum contents of six geese in each group were used for bacterial culture, isolation and counting. The cecal contents of other three geese in each group were taken, and primer sequences were designed according to the conservation of bacterial 16S rDNA. The V4 region genes of bacterial 16S rDNA were sequenced based on the IlluminaHiSeq sequencing platform, and microbial species diversity was analyzed based on the sequences.Result A total of 1 066 175 high-quality bacterial 16S rDNA sequences were obtained from group A, B and C. The total number of operational taxonomic unit(OTU) shared by three groups was 1 013, the contribution rate of principle component 1 (PC1) to total microbes was 46.64%, and the contribution rate of principle component 2 (PC2) was 16.46%. The dominant flora at the phylum level were Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, Verrucomicrobia and etc. The dominant flora at the family level were Bacteroidaceae, Enterobacteriaceae, Lachnospiraceae, Ruminococcacea, and Rikenellaceae. The dominant flora at the genus level were Akkermansia, Bacteroides, Corynebacterium and Lactococcus. Comparing with group A, the number of Bifidobacteria in group C was significantly lower (P < 0.05), and the number of Escherichia coli and Salmonella in group C were significantly higher (P < 0.05).Conclusion Feeding high-protein diet can change the diversity and abundance of cecal microflora in goslings, reduces the number of bifidobacteria and lactobacilli, and increases the number of E. coli and Salmonella.

Abstract:Objective To study the molecular prevalence of the porcine peproductive and respiratory syndrome virus (PRRSV) strain in small and medium-sized pig farms of Fujian province in 2017.Method We collected 83 suspected blue ear positive disease materials from small and medium-sized pig farms in Fujian province. RT-PCR detection and genetic evolution analysis of ORF5 gene which encoded GP5 protein was performed.Result The positive rate of 83 suspected blue ear disease samples was 73%, and the nucleotide similarity among the measured ORF5 sequences was 80.3%-100.0%. The nucleotide similarities between tested strains of different branches and the representative strains of those branches, NADC30, GM2 and JXA1, were 92.6%-93.9%, 89.8%-93.0% and 93.4%-99.3%, respectively. The new identified strain in the new branch had nucleotide similarity of 91.0%-93.0% to JXA1. The GP5 amino acid alignment showed significant variation in functional regions such as GP5 signal peptide region, induction epitope, principal neutralizing epitope and hypervariable region in different subgroups.Conclusion A new branch of PRRSV has emerged in Fujian area, making the PRRSV variants in Fujian more diverse. It is necessary to strengthen the monitoring of PRRSV epidemics and mutations.

Abstract:Objective To explore the effect of sugarcane (Saccharum officinarum)-mungbean(Vigna radiata) intercropping and different nitrogen application levels on sugarcane growth, yield and nitrogen nutrition, and provide a reference for rational sugarcane intercropping.Method Three cropping patterns (monocropping of mungbean, monocropping of sugarcane, intercropping of sugarcane and mungbean with mungbean straw returning), and three nitrogen treatments (no N application, reduced N application, conventional N application) were used in the experiments. Sugarcane traits during different growth period were measured.Result Tiller number, dry biomass, nitrogen uptake, number of millable stalks and cane yield of sugarcane were significantly affected by nitrogen level and cropping pattern. Sugarcane emergency number was also significantly affected by cropping pattern. Number and percentage of millable stalks, dry biomass and nitrogen uptake of sugarcane were significantly affected by nitrogen level×cropping pattern. Compared with monocropping of sugarcane, intercropping treatment reduced emergency number and tiller nubmer by 9.61%-10.52% and 10.30%-11.05% respectively, while increased number of millable stalks, dry biomass, nitrogen uptake and cane yield of sugarcane by 0.15%-14.28%, 14.28%-34.76%, 24.00%-29.58% and 15.88%-20.16%, respectively. For the intercropping treatment, the land equivalent ratio was 1.47-1.53 after sugarcane grew for 80 days, and the land equivalent ratio at sugarcane harvest was 1.76-1.94. The competition ability of sugarcane was greater than that of mungbean. Compared with monocropping of sugarcane with conventional N application, intercropping treatment with reduced N application did not decrease cane yield and soil nitrogen level.Conclusion Intercropping of sugarcane and mungbean can increase the land equivalent ratio and soil nitrogen level, promote sugarcane growth and increase cane yield and nitrogen uptake.

Abstract:Objective To establish a set of method suitable for quality evaluation of biochar and to explore the main factors influencing biochar quality.Method Toally 24 biochars (Y1-Y24) were prepared from eight biomass materials under three different temperatures. Sixteen quality indexes of biochars were measured, and the data were converted using the subordinate function. SPSS 19.0 was used for factor analysis. Factor loading matrix was obtained using the biquadratic maximum rotation method. The comprehensive evaluation scores were calculated. Correlation analysis and factor analysis were performed for the 16 indexes, and the comprehensive evaluation system of biochar quality was established based on factor analysis. The biochars were ranked using the comprehensive evaluation scores.Result Through factor analysis of 16 quality indexes of 24 biochars, we extracted five common factors with eigenvalues above one and their cumulative variance contribution was 77.910%. The first common factor consisted of carbon content, cation exchange capacity (CEC) and pH, with variance contribution of 31.090%. The second common factor consisted of specific surface area and pore volume, with variance contribution of 19.878%. The third common factor consisted of hydrogen atom content with variance contribution of 12.819%. The fourth common factor consisted of phosphorus and potassium contents with variance contribution of 7.479%. The fifth common factor consisted of maximum adsorption capacity of NH₄⁺-N with variance contribution of 6.643%.Conclusion Factor analysis is a good statistical method for evaluating biochar quality. The key factors affecting biochar quality include chemical characteristic factors (C content, C/N ratio, C/H ratio, pH and CEC), physical characteristic factors (specific surface area and pore volume), active energy factor (H atom content), nutrition factor (P and K contents) and maximum adsorption capacity of NH₄⁺-N.

Abstract:Objective Dynamic changes of nutrient contents in soil applied with pig manure were studied with the aim to offer guideline for reasonable manure application in litchi production.Method The variations of macro-, secondary and micro-nutrients in soils applied with different contents (w=0, 1%, 2% and 4%) of pig manure were investigated during 360 days of incubation test.Result In soil deficient of available N, P, K, Ca, Mg and medium of available Mn, Cu and Zn, after pig manure was applied at the content of 1%, the contents of all soil nutrients immediately reached abundant levels, except that exchangeable Ca and Mg contents reached medium levels. As the manure application rate increased, soil alkali-hydrolyzable N maintained at rich level with shorter duration and then decreased more sharply, while soil available P, K, Ca, Mg, Fe, Mn, Cu and Zn contents significantly increased (P < 0.05). Moreover, soil nutrient (except available K and Fe) contents had larger fluctuations, leading to lower stability of soil nutrient supply.Conclusion Pig manure is a quality nutrient source for crop and is recommended to be applied at the rate of no more than 1%, namely 15 t·hm^-1 in litchi production. Simultaneously, the application rates of inorganic N and K fertilizers should be reduced, and some other inorganic fertilizers such as P, Fe, Mn, Cu and Zn should be withdrawn.

Abstract:Objective To study the influences of different soil management methods on soil temperature, soil moisture and Citrus reticulata growth in citrus orchard during summer drought season.Method The experiment was carried out in Beibei, Chongqing using Ziyangxiangcheng (Citrus junos Sieb. ex Tanaka) Zhenwogan (Citrus reticulata cv. Orah) as the material. Four soil management systems, including rotary tillage weeding (CK), mechanical weeding mulch (MWM), chemical weeding mulch (CWM) and weed living mulch (WLM), were used during the summer drought seasons of 2016 and 2017. We measured the temperature at soil layers of 0 (surface),10, 20 and 30 cm depth, the moisture at 0-10, 10-20 and 20-30 cm soil layers, the maximum crack width of surface, citrus root activity and autumn shoot growth, and summarized the costs of different soil management systems.Result The shallower the soil layer, the greater the fluctuation of soil temperature and water content. In general, the daily average temperature, maximum temperature and daily temperature range of each soil layer under different soil managements were CK > CWM > MWM > WLM. Under extreme high temperature weather (air temperature 41 ℃), the highest soil surface temperatures of CK, CWM, MWM and WLM were 69.6, 45.6, 37.5 and 35.0 ℃, respectively. The water contents of different soil layers were the highest in WLM and MWM, and the lowest in CK. The water content in 0-10 cm soil layer of CK was significantly lower than those of other treatments. For both citrus root activity and autumn shoot growth, the results were MWM > CWM > CK > WLM. The costs of different soil management systems were in order of CK > WLM > MWM > CWM.Conclusion Considering the effect, cost and operability, the flat or gentle slope citrus orchard should be practiced with MWM soil management during summer drought season.

Abstract:Objective To investigate the effect of different casing materials on growth and development of Calocybe indica, and provide a theoretical basis for introduction and cultivation of Calocybe indica in China.Method Different casing materials including loamy soil(CK), loamy soil+cow dung (volume ratio was 3:1), spent mushroom compost, loamy soil+sand (volume ratio was 3:1) were used as casing materials for cultivation of mushroom C. indica, and their effect on the yield and agronomic performance of C. indica sporophore were evaluated. Changes in soluble protein content and extracellular enzyme activity were measured.Result Using loamy soil+cow dung as the casing material resulted in the highest yield of 2 078.50 g, the highest fruiting density and the shortest time for primordium initiation of around 7.67 days. When spent mushroom compost was used as the casing material, the yield and fruiting density of C. indica were ranked second, while the time of primordium initiation was the longest being 22.67 days. Compared with the control treatment, loamy soil+sand resulted in lower yield and fruiting density as well as worse fruiting quality. During different growth stages, in general soluble protein contents in different treatments showed a rising trend and largely increased during the second flush of C. indica (except for spent mushroom compost treatment). Soluble protein content in loamy soil+cow dung treatment was the highest during the whole growth process. Changes of extracellular enzyme activities were the most beneficial to C. indica growth under loamy soil+cow dung treatment.Conclusion Considering C. indica growth status and economic benefits, it is recommended to use loamy soil+cow dung as the casing material.

Abstract:Objective To study the effect of glycine incubation on the stability of lipase immobilized by LXEP-120 epoxy resin.Method Glycine solution was used to incubate lipase immobilized by epoxy resin for removing the residual epoxy groups. The incubation conditions were explored and optimized, and the enzymatic properties of the immobilized lipase before and after incubation were compared.Result The optimal incubation conditions were 2.5 mol/L and pH 7.0 glycine solution incubating for 24 h at 25 ℃. Following incubation, the immobilized lipase still retained about 60% of the original activity after treatment at 80 ℃ for 6 h, while the unincubated immobilized lipase retained only about 45% of the original activity. The optimal reaction pH (8.0) and optimal reaction temperature (45 ℃) of the immobilized lipase after incubation were the same as those of the unincubated immobilized lipase, and the pH tolerance, operation stability, and storage stability were the same as those before incubation.Conclusion Removing residual epoxy groups on immobilized enzyme through incubation is one necessary technical step. Glycine incubation can greatly improve the thermal stability of the immobilized lipase with little influence on reaction pH, pH stability, operation stability and storage stability.

Abstract:Objective To isolate and identify endophytic fungi from branches and fruits of Casuarina equisetifolia Forst., and screen active endophytic fungi with antibacterial and antioxidant activities.Method Endophytic fungi from branches and fruits of C. equisetifolia were isolated by the tissue block separation method, and identified by combining colony observation with molecular biology. The antibacterial activities of secondary metabolites produced by endophytic fungi against different bacteria were determined using TLC-bioautography and their antioxidant activities were determined using the multi-orifice plate-DPPH coloration method.Result Twelve strains were isolated and identified from branches and fruits of C. equisetifolia. There were significant difference between endophytic fungi isolated from branches and fruits. There were only two same endophytic fungus strains in branches and fruits, namely Cef-1 (Pseudofusicoccum sp.) and Cef-7 (Pestalotiopsis sp.). All endophytic fungi were mainly distributed in nine different genera, including Pseudofusicoccum, Botryosphaeria, Pestalotiopsis, Trichoderma, Aspergillus, Rhytidhysteron, Phomopsis, Fusarium and Colletotrichum. Among them, Botryosphaeria had the most species and was the dominant species, followed by Pestalotiopsis. Cef-2 (Botryosphaeria sp.) showed the strongest inhibitory activity and the diameters of antibacterial spots were more than 10 mm, which were stronger than that of the positive control streptomycin sulfate. Cef-1 and Cef-9 (Fusarium sp.) showed well inhibition on Ralstonia solanacearum. Cef-2 displayed the best antioxidant activity and the IC₅₀ value was 0.80 mg/mL.Conclusion There are endophytic fungi in branches and fruits of Casuarina equisetifolia, and Botryosphaeria is the dominant species. There are significant differences of fungi species between branches and fruits. Endophytic fungus Cef-2 exhibits the strongest antibacterial and antioxidant activities, which can be used as a candidate strain for further isolation and identification of active component.

Abstract:Objective To compare the accuracy of different height(H)-diameter (D) models to determine the optimal models for Pinus sylvestris var. mongolica in Zhanggutai area.Method Sibbesen model was used as the basic model. Dominant height (H_T), stand basal area (A_B), and quadratic mean diameter (D_QM) with different combinations were added into Sibbesen model. We established one basic, three generalized, one basic mixed and three generalized mixed H-D models. The accuracies of population-averaged prediction (FPA) of fixed effects models, and mean response prediction (MPA) and specific-plot prediction (MPS) of mixed effects models were compared. For mixed models, two sampling designs, random sampling and medium-diameter tree sampling were used for random parameters estimation, and the relationship between MPS accuracy and sample size was analyzed.Result In four fixed H-D models, the generalized model with H_T and A_B has the highest prediction precision. Akaike’s information criterion (AIC) is 2 167.7. Bayesian information criterion (BIC) is 2 196.3. Models with the same predictor variables have precision in order of MPS > FPA > MPA, and models with D as the only variable have the largest variation among three types of prediction. There are little difference in prediction accuracy among generalized models, generalized mixed models and basic mixed model. Using three randomly selected sample trees per plot to estimate random parameters of basic mixed model results in the highest model precision based on the validation data, and MAE and RMSE decrease by 57.97% and 57.63% respectively. The accuracies of generalized mixed models do not change significantly with the increase of sample size.Conclusion Both generalized model including H_T and A_B and basic mixed model can well predict tree height for P. sylvestris var. mongolica. We recommend to randomly select three sample trees per plot measuring tree heights for parameters estimation of mixed models, and calculating random parameters.

Abstract:Objective To clone the full-length cDNA sequence of 9-cis-epoxycarotenoid dioxygenase (NCED) gene from leaves of Pyrus bretschneideri ‘Xuehuali’ × P. pyrifolia ‘Shinsseiki’ cultivar ‘Huangguan’，study the relationship between its expression and the endogenous abscisic acid (ABA) content in leaves under different degree of drought, and provide a theoretical basis for understanding the molecular mechanism of the gene in drought resistance of pear tree.Method According to the PbpNCED3 sequence obtained from the transcriptome data, the full-length cDNA sequence was cloned by homologous sequence amplification. The sequence was identified as belonging to the NCED family by bioinformatics analysis. Endogenous ABA content in pear leaves under different soil moisture conditions was determined by enzyme-linked immunosorbent assay (icELISA), and the expression of PbpNCED3 gene was measured by real time qPCR.Result The PbpNCED3 cDNA sequence is 1 831 bp encoding 603 amino acids. The protein has four conserved histidines required for activity, two conservative domain (MIAHPKxDP and HDFAITE) characteristic of the NCED family and a RPE65 domain. There is a putative chloroplast-targeting peptide at N-terminal. The protein structure prediction shows that the protein sequence has 70% similarity to vp14 (NCED family protein) and it has a amphipathic α helix structure. PbpNCED3 gene expression is positively related with ABA content in pear leaves with a correlation coefficient of 0.914, and both of them are induced by drought.Conclusion The PbpNCED3 gene obtained from the experiment belongs to the NCED family. It responses to drought stress and its expression shares a similar dynamic trend with ABA content in pear leaves.

Abstract:Objective Flight quality of plant protection UAV is an important factor affecting the effectiveness of aerial spraying. The objective of this research is to explore flight qualities and operation effects of plant protection UAVs of different types and control models, which can provide data support and guidance for selecting the models and improving the spraying technologies.Method Flight paths and parameters of single-rotor oil-powered plant protection UAV(Se-UAV), single-rotor electric plant protection UAV(Se-UAV), semi-automatic-quad-rotor electric plant protection UAV(Saqe-UAV) and full-automatic-quad-rotor electric plant protection UAV(Faqe-UAV) were obtained by micro-light Beidou navigation satellite system, and flight qualities (including path accuracy, variation uniformity of flight parameter and path length) were analyzed and evaluated.Result Flight qualities of quad-rotor plant protection UAVs were better than those of single-rotor plant protection UAVs, and flight quality of Faqe-UAVwas better than that of Saqe-UAV. Faqe-UAV had the best uniformity of flight parameters throughout the operating area, and the uniformities of flight speed and flight height were 3.66% and 4.67%, respectively. The average route deviation of Faqe-UAV was the minimum, which was 0.172 m. In addition, the effects of flight direction on flight parameters of plant protection UAVs under full-autonomous and semi-autonomous control modes were insignificant and significant respectively. The effect of route length on flight parameters of plant protection UAV under semi-autonomous control mode was not significant, but route length had a significant effect on flight speed of plant protection UAV under full-autonomous control mode.Conclusion In the aerial spraying process, quad-rotor plant protection UAV under full-autonomous control mode has the best flight quality, and gives spraying quality more security.

Abstract:Objective To identify cotton pests quickly and accurately without destruction，and formulate pertinently a plant protection spraying plan.Method Hyperspectral data of cotton leaves were collected and analyzed. FieldSpec^®3 portable spectrum analyzer with a wavelength range of 350-2 500 nm was used to obtain hyperspectral data of cotton leaves including normal leaves and leaves infected by aphids and red spiders. K-nearest neighbor and SVM algorithm were used to distinguish above leaves. In order to further optimize pest identification of the model and improve the recognition accuracy, the principal component analysis method (PCA) was used for feature dimension reduction, and the grid search method was used for parameter optimization.Result The models of pest identification were constructed by K-nearest neighbor algorithm and SVM algorithm，and recognition rates of two models were 86.08% and 89.29% respectively. Recognition rate increased after introducing PCA for feature dimension reduction and using grid search for parameter optimization. The recognition accuracies of K-nearest neighbor algorithm and SVM algorithm reached 88.24% and 92.16% respectively.Conclusion Hyperspectral data can be used to distinguish aphid or red spider-infected leaves and normal cotton leaves. Using PCA dimensionality reduction and grid search method, the recognition rate can increase without obtaining specific characteristic bands. For identifying aphid- or red spider-infected leaves and normal leaves, SVM algorithm based on radial basis kernel function is better than K-nearest neighbor algorithm.

Abstract:Objective To quickly and non-destructively detect polysaccharide content in Pleurotus eryngii using hyperspectral imaging technology.Method Hyperspectral images of P. eryngii in the visible and near infrared (390-1050 nm) regions were acquired using the hyperspectral imaging system. Polysaccharide contents in corresponding P. eryngii samples were measured by phenol sulfuric acid method. The binary mask image was constructed by the method of band operation and threshold segmentation to separate the sample area from the background area. Principal component analysis (PCA) was used to process the original hyperspectral images, and two principal component images (PC1, PC2) representing 99% information of the original image were obtained. Seven characteristic wavelengths of 554.4, 772.8, 811.4, 819.1, 855.6, 986.3, and 1 019.5 nm were selected using the successive projection algorithm (SPA). Texture and color data were extracted from two principal component images and seven characteristic wavelength images, and spectral data were also extracted from seven characteristic wavelength images. Using partial least squares regression (PLSR) models were established based on the correlations of different image features and polysaccharide contents in P. eryngii samples Result According to the determination coefficient of the calibration set (R_c²), the best model is the one based on characteristic spectra, characteristic wavelength images and principal component images with R_c²=0.954 and RMSE_C=0.341. According to the determination coefficient of the prediction set (R_p²), the best model is the one based on characteristic spectra and characteristic wavelength images with R_p²=0.868 and RMSE_P=0.539.Conclusion This study provides references for fast and non-destructive detection of polysaccharide content in Pleurotus eryngii.

Abstract:Objective To solve the driver control problem of carrying dead pig vehicle based on high-power permanent-magnet brush DC motor.Method We used STM32 MCU as a main controller, used the current closed-loop control method, and built the driving control system based on high-power permanent-magnet brush DC motor through hardware circuit design. We designed motor forward and reverse control circuit, speed regulating circuit, current detection circuit and over-current protection circuit with relay as the change-over switch. The motor speed was adjusted by Pulse Width Modulation (PWM). The driving control system was tested and analyzed on vehicle carrying dead pigs.Result The drive system could effectively drive 1.1 kW high-power brush DC motor, and stably start with a large starting torque. The speed regulation of motor was stable with a large range. When the duty ratio of PWM ranged from 16% to 95%, the rotating speed of motor changed from low speed after stable start-up to full speed. Dual motors had good coordination, reliable isolation protection and over-current protection measure. Under the continued large current, this system could work stably, met the needs of heavy load of vehicle, and basically achieved the intended function of carrying dead pig vehicle.Conclusion The drive control system has start-up stability and good performance of speed regulation, which provides a solution to solve the driving problem of high-power permanent-magnet brush DC motor.

Abstract:Objective To explore the feasibility of sugarcane vertical clamping-conveying technology for the whole stalk harvester, and provide a technical support for solving the problem of long sugarcane channel and low working efficiency of the existing stalk-type sugarcane combine harvester.Method A kind of vertical stripper was designed in a clamping-conveying channel for 4ZZX-48 sugarcane harvester . A harvesting test of this device was conducted in field. The influence factors of leaf stripping effect were analyzed, including the rotation rate of conveyor chain sprocket(n₁), the installation angle of leaf stripping roller(β), the rotation rate of leaf stripping roller(n₂) and sugarcane feeding speed(q)Result The values of n₁ and n₂ had significant impact on leaf stripping effect. The ranking of influence was n₁ > n₂ > q > β. When n₁ was 60 r/min, n₂ was 360 r/min, β was 30° and q was 7.5 kg/s, the machine got the best stripping effect and leaf stripping rate was 76.6%. The results of curve regression analysis showed that there was a quadratic polynomial relation between clearing rate and the ratio of n₂ to n₁. When the value of n₂/n₁ ranged from 5 to 6, clearing rate reached the maximum of around 77%.Cluclusion This harvester, based on sugarcane vertical clamping-conveying and stripping technology, is feasible and has certain reference value for research and development of a new whole stalk sugarcane harvester.

Abstract:Objective A novel kind of air-blowing precision seed-metering device was designed in order to fulfill the mechanized planting needs of Panax notoginseng and reduce seed damage in the process of mechanical seeding.Method The main structural parameters of the seed-metering device were determined. The mechanical model in seed clearing process was established. The internal flow field model of the seed-metering device was established, Fluent software was used to simulate the flow field under different air-blowing pressure, and the range of air-blowing pressure for seed clearing was verified. We used orthogonal design and performed bench test to further examine the feasibility of the range of air-blowing pressure and find out the optimal combination of working parameters. Eligible index, leakage sowing index and repeat sowing index were selected as experimental indexes. Operating speed, seed layer height and air-blowing pressure were selected as the influencing factors in the test.Result The optimal combination of parameters was the operating speed of 0.6 m/s, seed layer height of 90 mm and air-blowing pressure of 0.5 kPa. Under these conditions, the qualified index was 90.48, the leakage sowing index was 4.24, and the repeat sowing index was 5.28.Conclusion The air-blowing seed-metering device can meet the requirements of Panax notoginseng seeding. This study provides a theoretical basis for the field experiment of the seed-metering device. Comparison between the test results and the simulation analysis indicates that the influence of air-blowing pressure changes on the filling performance of the seed-metering device is consistent, and Fluent simulation is feasible for determining the air-blowing pressure for seed clearing.