Abstract:Objective To prolong the maintenance time of the effective blood concentration of the drug, generate a sustainable and stable bacteriostatic action, and avoid embryotoxicity and immunosuppression in multi-dose continuous use of florfenicol.Method The test used hardened oil, polyethylene glycol and glyceride as auxiliary materials. The florfenicol sustained-release granules were prepared by centrifugal spray drying granulation method, and the content of florfenicol was determined by high performance liquid chromatography (HPLC). Using release characteristics of the drug in different media (pH 1.2 hydrochloric acid buffer, pH 4.3 acetate buffer and pH 6.8 phosphate buffer) as indicators, the dissolution tests of florfenicol powder and self-made florfenicol sustained-release granules were carried out to investigate their in vitro release performances.Result The percentages of florfenicol actual contents in indicated contents of florfenicol sustained-release granules prepared in four batches were 99.19%, 100.01%, 97.45% and 100.72%, and the relative standard deviations (RSD) were 0.82%, 0.86%, 0.77% and 0.24% respectively. The florfenicol powder was completely released within 0.25 h. The self-made florfenicol sustained-release granules were substantially not released in simulated gastric fluid environment (pH 1.2 hydrochloric acid buffer), and released slowly under simulated intestinal fluid environment (pH 4.3 acetate buffer and pH 6.8 phosphate buffer) with the release amount of over 95% within 5 h.Conclusion The drug in self-made florfenicol sustained-release granules is homogeneous distributed, and the granules conform to China veterinary pharmacopoeia. Compared with florfenicol powder, florfenicol sustained-release granules show good acid resistance and in vitro sustained-release performance, which provides a reference for subsequent clinical trial research and clinical use of drugs.

Abstract:Objective To isolate epidemic hemorrhagic disease virus serotype 6 (EHDV-6) strains prevalent in southern China, and investigate the genetic characteristics of the isolated strains.Method Blood samples were collected from sentinel animals in Yunnan and Guangdong Provinces in China. EHDV infection was monitored and the virus was isolated. The serum types of isolated strains were determined by serum neutralization test, and segments 2, 3 and 6 (Seg-2, -3 and -6) of EHDV-6 isolated strains were amplified by one-step RT-PCR and subsequently sequenced.Result From 2012 to 2016, 25 EHDV strains were isolated from sentinel animals in Yunnan and Guangdong Provinces and 11 strains of them were EHDV-6. Seg-2, -3 and -6 of Chinese EHDV-6 strains were of Eastern topotype, and the nucleic acid sequence similarities were 99.1%, 98.9% and 98.8% respectively, which were clustered into an independent Chinese branch on the phylogenetic tree. Chinese EHDV-6 strains had the closest relationship with the EHDV-6 strains which caused epidemic outbreaks in Japan. The Japanese EHDV-6 strain was within the Chinese branch on the phylogenetic tree. The similarities of nucleic acid sequences of Seg-2 and Seg-3 between the Japanese and Chinese strains were 98.5% and 93.9% respectively.Conclusion The sequences of EHDV-6 strains prevalent from Yunnan and Guangdong Provinces are highly similar. The closest genetic relationship between Japanese and Chinese EHDV-6 strains suggests that there may be flow of EHDV between China and Japan. The results provide a basis for further research on epidemiological analysis, pathogenicity, etiological diagnosis and vaccine preparation of EHDV-6 strains in China.

Abstract:Objective To investigate the effects of intrauterine growth retardation (IUGR) on immune organs and plasma cytokine contents in growing-finishing pigs.Method A total of 36 pregnant sows with similar body conditions were selected. After delivery, one IUGR piglet (IUGR group) and one normal born weight piglet (control group) were selected from each litter, respectively. After weaning, the animals were fed with the same basic diet. When the average body weight (BW) of control pigs gained 25, 50 and 100 kg, seven pigs per group were randomly selected to collect blood samples by precaval vein, and plasma cytokine contents were measured. Twelve pigs in each group were killed for isolating and weighing liver, spleen, and kidney to calculate their organ indices.Result Compared to the control group with the same BW, the liver, spleen and kidney weights of IUGR pigs decreased by 32.63%, 35.07% and 34.28% at 25 kg BW stage (P<0.01) and decreased by 22.68%, 40.05% and 33.03% at 50 kg BW stage, respectively. The content of plasma interleukin IL-1β in IUGR pigs at 25 and 50 kg BW stages decreased by 20.66% and 27.21% (P<0.05), respectively. Compared to the control group at 50 kg BW stage, the liver index of IUGR pigs increased by 16.25% (P<0.05) and the ratio of IL-1β to IL-10 decreased by 40.67% (P<0.01). Compared to the control group at 100 kg BW stage, the liver index and spleen index of IUGR pigs increased by 10.94% (P<0.05) and 21.74% (P<0.01), respectively, while the liver weight and kidney weight decreased by 13.97% and 17.51% (P<0.01), respectively.Conclusion IUGR can alter the organ indices and weights of liver, spleen and kidney, decrease plasma IL-1β content, and therefore influences the immune function in growing-finishing pigs.

Abstract:Objective To compare yield components and characterisitcs of hybrid rice with different mechanical transplanting methods under low sowing rate, and explore mechanical transplanting methods for hybrid rice.Method Two kinds of mechanical transplanting methods (mechanical transplanting of blanket seedling and mechanical transplanting of blanket seedling with bast fiber mulch film ) for early and late rice under low sowing rate were arranged and compared in Zhaoqing and Jiangmen in Guangdong Province. Artificial transplanting of pot seedling was used as the control. The robust seedlings were cultivated by precision sowing with low sowing rate. The accurate transplanting was achieved by transplanter.Result When the sowing rate was 65 g buds per plate, there was no significant difference between the actual yields of two kinds of mechanical transplanting and artificial transplanting of pot seedling, and the differences among three different transplanting methods in early and late rice experiments were 0.17%-0.66% and 1.01%-3.24%. The effective panicle number was the key influencing factor of yield. Ensuring moderate effective panicle number was the key for raising yield. The main difference of panicle traits of different transplanting methods was found in the number of secondary branch. There was little difference in the number of primary branch.Conclusion Mechanical transplanting of blanket seedling can realize high yield by increasing the proportions of middle panicle, cumulative proportion of large and middle panicles, and coordinating seed setting rate and other factors under low sowing rate.

Abstract:Objective To study the correlations between soil factors and effective components of Saposhnikovia divaricata, and screen out the leading factors affecting medicinal ingredients.Method The contents of four kinds of chromone (prim-O-glucosylcimifugin, cimifugin, 5-O-methylvisamminol, sec-O-glucosylhamaudol) in two-year-old S. divaricata from 16 regions were determined by HPLC , and 15 soil factors in rhizosphere soil were measured The relationships between chromone contents of S. divaricata and soil factors were studied by correlation analysis, cluster analysis and multiple linear regression analysis.Result S. divaricata of Datun Town in Hebei, Jingoutun in Hebei, Yantai in Shandong, Baicheng in Jilin and Wenzhong Town in Inner Mongolia had higher chromone contents. S. divaricata of Longde in Ningxia had the lowest content while S. divaricata in other ten regions had the medium chromone contents. The total chromone content of S. divaricata was significantly negatively correlated with soil conductivity, available phosphorus content and available calcium content (P<0.05), and positively correlated with available manganese content (P<0.05). The 16 regions were divided into four production areas including production area of Changchun in Jilin, production area of Longde in Ningxia, production area of Yantai in Shandong and other production areas (including Inner Mongolia, Hebei, Liaoning, etc.). Available phosphorus, available manganese and total phosphorus contents could explained 71.8% of the information of total chromone in S. divaricata.Conclusion There are significant differences in the qualities of S. divaricata from different regions. Available phosphorus and available manganese may play important roles in the formation of effective components of S. divaricata.

Abstract:Objective To analyze the difference of cultivated land quality in the study region, optimize the use and layout of cultivated land, and provide a reference for cultivated land protection.Method Taking the cultivated land in Gonghe County, Dulan County and Wulan County in Qinghai Province as the research object, the influencing factors of cultivated land quality were collected based on the history and existing literature, and the random forest algorithm and correlation analysis were used to screen the grading indicators and confirm the weight. We calculated the grading index and divided the levels by weighted sum method to get the grading result. We compared the results with the grading results of commonly used Delphi method.Result The value of variable importance I obtained by random forest algorithm ranged from 0.03 to 11.94. Correlation analysis showed that the correlation between most influencing factors was not significant, eight of which were significant correlation. The 14 rating indicators under four dimensions were astringed from 30 influencing factors. The main factors influencing the quality of cultivated land in the study area were ecosystem vulnerability, mean precipitation of growing season and annual solar radiation amount, with the weights of 0.11, 0.10 and 0.09, respectively.Conclusion Compared with Delphi method，the random forest algorithm has better stability and smaller level of index variation interval, which is more conducive to construct a comparable sequence of cultivated land levels at provincial spatial scale.

Abstract:Objective Rice sheath blight, caused by Rhizoctonia solani AG-1 IA, is an important fungal disease. The purpose of this study was to determine the relationship between external culture conditions and melanin formation of R. solani AG-1 IA.Method The effects of four different treatment groups, i. e. chemical fertilizer group [500 μg/mL K₂SO₄, NaH₂PO₄, CO(NH₂)₂], metal ion compound group(5 μg/mL CuSO₄, FeSO₄, ZnSO₄), antioxidant group (5 μg/mL quercetin, morin, vitamin C) and control group (300 μg/mL hyoscyamine, 50 μg/mL catechol, water), on the mycelial growth rate, sclerotia number, sclerotial fresh weight and dry weight as well as melanin content of R. solani AG-1 IA were determined by measuring mycelial growth rate and ultraviolet spectrophotometry.Result Chemical fertilizer [500 μg/mL K₂SO₄, NaH₂PO₄, CO(NH₂)₂], metal ion compound (5 μg/mL CuSO₄, ZnSO₄), antioxidant(5 μg/mL quercetin, morin, vitamin C) and catechol(50 μg/mL) could promote the formation of melanin. Under the treatment of 500 μg/mL CO(NH₂)₂, the melanin content of R. solani AG-1 IA was the highest (113.2 mg), while under the treatment of 300 μg/mL hyoscyamine, the melanin content of R. solani AG-1 IA was the lowest (37.4 mg).Conclusion Melanin formation is not necessarily related to mycelial growth and sclerotial development, i.e. the chemical substances, which have inhibitory effect on mycelial growth and sclerotial development, might have no inhibition on melanin formation. The results of this study provide a basis for understanding the mechanism for prevention and control of rice sheath blight.

Abstract:Objective To identify 29 strains of entomogenous fungi and select high virulent strains against Bemisia tabaci.Method Identification of fungi were based on morphological analysis and genetic homology analysis of sequences in ITS, TEF and Bloc regions. The fungal toxicity to B. tabaci was evaluated by the immersion method.Result Twenty-six of 29 entomogenous fungal strains had the characteristics of Beauveria and the other three strains of SB003, SP665 and SP670 were identified as Isaria. Phylogenetic tree was constructed using TEF region sequence, Bloc region sequence and TEF-Bloc combined sequence, which showed that 29 strains included 24 strains of Beauveria bassiana, 2 strains of B. pseudobassiana, and 3 strains of Isaria cateinannulata. The mortality of the 2nd instar nymph of B. tabaci increased with the increase of spore concentration, and the pathogenicity of different strain was different. The 2nd instar nymphs of B. tabaci were treated with 1×10⁸ mL^-1 spore suspension for 7 days, and the SP433 strain had the highest lethality rate of 87.37%, followed by SB009 with a lethality rate of 82.93%.Conclusion This study can provide a theoretical basis for the classification of entomophytic fungi. The highly pathogenic strains of SP433 and SB009 were screened out, which can provide a reference for the biological control of B. tabaci.

Abstract:Objective To investigate the effects of short-term exposure to high temperature at larval stage on the survival rate, development and fecundity of Assara inouei.Method Neonate larvae or mature larvae of A. inouei were exposed to high temperatures of 35, 38, 41 and 45 ℃ for 1, 2 and 4 h, respectively, and the survival rate was measured. After neonate larvae or mature larvae of A. inouei were exposed to high temperatures of 35, 38 and 41 ℃ for 1, 2 and 4 h, respectively, biological parameters of developmental duration, pupation rate, emergence rate, male and female longevity, number of eggs laid per female and egg hatching rate were investigated.Result The survival rate of neonate larvae decreased gradually with the increase of temperature and treatment time. The developmental duration of neonate larvae was shortened by 35 ℃ treatment, but the developmental durations were prolonged by 38 and 41 ℃ treatments. After mature larvae were exposed to high temperature for short term, the pupation rate, pupal weight, emergence rate, oviposition period, female longevity and number of eggs laid per female decreased gradually, and pupal duration prolonged gradually with the increase of temperature and treatment time.Conclusion Neonate larvae have higher adaptability to short-term high temperature than mature larvae. Short-term exposure to high temperature has significant effects on the survival, development and fecundity of mature larvae of A. inouei. The results reveal the adaptability of A. inouei larvae to high temperature, and provide a scientific basis for predicting the population dynamics of A. inouei.

Abstract:Objective Opisina arenosella is an important invasive leaf-eating pest that attack Palmae plants. The goal was to analyze the distribution characteristics of haplotypes of O. arenosella in native and invaded zones, and reveal the insect source information of O. arenosella invading China.Method A total of 172 samples from 16 geographical populations were analyzed by mitochondrial COI gene, and the genetic relationship of O. arenosella from India and invading areas (China, Malaysia and Thailand) was compared.Result Twelve haplotypes were identified in 172 sequences with fragment length of 625 bp. Fifteen variation sites were detected in the haplotype alignment. Two obvious haplotype branches were formed, one of which was composed of 11 haplotypes IN1-IN11 and they were all from Indian populations. Haplotype IN1 was shared by six O. arenosella populations from India. IN2-IN11 were exclusive haplotypes and not shared with other populations. The other branch was haplotype HAP and shared by populations from China, Malaysia and Thailand. There were four variation sites between HAP and 11 haplotypes IN1-IN11 from India.Conclusion O. arenosella populations in these invading areas are from the same genotype type or have the same invasion source. O. arenosella invading populations produce new mutations or hybrids in new habitats under environmental selection pressure.

Abstract:Objective To clone the coding sequence of proL gene in the endophytic fungus Cytospora rhizophorae derived from Morinda officinalis, obtain ProL protein by heterologous expression and investigate its physicochemical properties, thereby providing a basis for the subsequent research on biological function of the ProL in the biosynthesis pathway of new bioactive compounds cytorhizins.Method The proL gene from C. rhizophorae was amplified by PCR, the proL gene fragment was inserted into the prokaryotic expression vector of pET28a by the homologous recombination method and heterologously expressed in Escherichia coli. The ProL protein was renatured by refolding buffer containing urea with a gradiently decreased concentration, and SDS-PAGE analysis and mass spectrometry sequencing were used to verify the target ProL protein. The bioinformatic methods were employed to analyze the similarity of ProL protein with other related proteins, and predict the structure and function of ProL protein.Result The coding sequence of proL gene was cloned, the open reading frame of proL gene is 909 bp in length, which encodes 303 amino acids, the molecular formula of ProL is C₁₄₉₅H₂₃₂₀N₄₂₄O₄₄₄S₁₃, the relative molecular weight is 33 754.22, the total number of atoms is 4 696, PI is 5.69, so ProL is an acidic protein. ProL protein was abundantly expressed as inclusion bodies in E.coli, the recombinant ProL was obtained with a purity of 98.9%. Bioinformatics analysis results indicated that ProL protein had the highest amino acid sequence similarity (59.40%) with amidohydrolase 2 from Aspergillus ibericus XP025570169.1. The three-dimensional structure model of ProL protein is composed of eight α-helixes and eight β-folds. The conserved amino acid sequence is located at the position from 207 to 216.Conclusions ProL protein belongs to the amidohydrolase superfamily, and is predicted as a novel protein. ProL protein might play a role of hydrolysis in the biosynthesis pathway of highly oxidized benzophenones.

Abstract:Objective Growth property, wood property and oleoresin trait are target traits in the new round of slash pine (Pinus elliottii ) genetic improvement. The goal was to analyze phenotypic performance, heritabilities and trait correlations of tree height, diameter at breast height (DBH), individual volume and resin mass, and provide a theoretical basis for developing breeding strategies for multiple traits.Method Thirty-two open-pollinated families of 18-year-old P.elliottii in Taishan City of Guangdong Province were tested. Resin samples at breast height were collected for 24 hours, the mass was determined and the amount of growth was measured. The trait heritabilities and correlations between traits were estimated using Asreml.Result The resin mass (m) presented positively skewed distribution, and its coefficient of variation was higher than those of the growth traits, reaching 75.04%. The individual narrow-sense heritability and family average heritability for transformed resin mass (m_t) were 0.216 1 and 0.600 5. The narrow-sense heritabilities for growth traits ranged from 0.252 7 to 0.415 1, and the family average heritabilities ranged from 0.648 3 to 0.751 2. The genetic correlations among tree height, DBH and individual tree volume were strong with the correlation coefficients from 0.813 to 0.983(P＜0.001), and their genetic correlations with wood density were medium and significantly positive(P＜0.05), while the standard errors were large. No significant correlation was found between resin mass and the above traits.Conclusion To select individual performing well in oleoresin and wood properties, it is reliable to combine family selection and within-family selection. It’s possible to simultaneously improve growth, wood density and resin mass using current genetic materials of P. elliottii.

Abstract:Objective To explore antibacterial activity and mechanism of garlic organic sulfide (GOS) against Bacillus amyloliquefaciens.Method The antimicrobial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of GOS against B. amyloliquefaciens strain were determined using the inhibition zone method and the double dilution method, and its inhibitory effects on bacterial growth curve and extracellular protease activity were evaluated. Metabolic activity, alkaline phosphatase activity, β-galactosidase activity, extracellular conductivity and thallus morphological changes observed through scanning electron microscope of B. amyloliquefaciens treated with GOS were investigated for elucidating antibacterial mechanism of GOS against B. amyloliquefaciens.Result Diameter of inhibitory zone of GOS against B. amyloliquefaciens DY1a and DY1b were 31.7 and 25.7 mm respectively, MIC of both strains were 30 mg/mL, MBC were 240 and 480 mg/mL, respectively. The inhibition rate of 30 mg/mL GOS on DY1a and DY1b extracellular protease activity were 47.3% and 15.6% respectively. After treatment with 30 mg/mL GOS, metabolic activity (D_{490 nm}) decreased by 2.771 and 4.091 respectively, extracellular alkaline phosphatase activity increased by 0.029 and 0.036 U/mL, extracellular β-galactosidase activity (D_{420 nm}) increased by 0.047 and 0.016 respectively and the extracellular electrical conductivity increased by 0.060 and 0.031 mS/cm respectively. The results of SEM showed that the surface of bacteria cells treated with GOS had shrinkage, cavity collapse and rupture.Conclusion The excellent antibacterial effect of GOS against B. amyloliquefaciens may be attributed to irreversible damage to cell wall and cell membrane and alterations of cell physiological metabolism.

Abstract:Objective To reduce the cost of pretreatment and improve the enzymatic hydrolysis effect after straw pretreatment, sorghum straw was pretreated with simulated natural low temperature environment and ammonia water.Method We studied the effects of the liquid-solid ratio in soaking solution, freezing temperature, freezing time and ammonia content in pretreatment using ammonia water combined with freezing and thawing on enzymatic hydrolysis of sorghum straw through single factor tests. We optimized the pretreatment conditions using orthogonal test design. The compositions of sorghum straw before and after pretreatment were measured using normal form method, and the physical and chemical structures were investigated using infrared spectrum and X-ray diffraction analyses.Result In single factor tests， liquid-solid ratio in soaking solution, freezing temperature, freezing time and ammonia content at different levels all significantly increased the production of reducing sugar through enzymatic digestion(P<0.05). The optimum pretreatment conditions of the orthogonal test were 12 liquid-solid ratio in soaking solution, 12 h freezing time, 10 ℃ freezing temperature, and ammonia content of 8%. Compared with straw without pretreatment, in straw with pretreatment using ammonia water combined with freezing and thawing, the hemicellulose content decreased by 42.42% , the lignin content decreased by 50.76%, the yield of reducing sugar for straw was 302.87 mg·g^-1, which was 80.34% higher than that of straw without pretreatment, and the crystallinity of cellulose increased by 57.02%.Conclusion The pretreatment using ammonia water combined with freezing and thawing can effectively destroy the original connection structure between lignocellulose of sorghum straw, dissolve hemicellulose, destroy the monomer and polymeric structure of lignin. It improves the yield of reducing sugar by enzymatic hydrolysis of sorghum straw, and also improves the crystallinity of sorghum straw cellulose.

Abstract:Objective To explore the capability of deploying deep learning to the detection of Huanglongbing (HLB) symptom in Citrus spp., and evaluate the classification accuracies of the classifiers.Method Two-class classifiers(I-2-C and M-2-C) and eight-class classifiers(I-8-C and M-8-C) were constructed using images of diseased leaves caused by HLB/non-HLB and healthy leaves based on convolutional neural networks and transfer learning.Result The overall classification performance of M-8-C stood out in all classifiers with accuracy of 93.7%, implying great capability in deep convolutional neural networks for classifying HLB symptoms. The mean F1 socres of I-8-C and M-8-C were 77.9% and 88.4% respectively, which were higher than those of I-2-C(56.3%) and M-2-C(52.5%). This indicated that subtyping symptoms could help improve the recognition ability of models. The slightly higher mean F1 score of M-8-C compared with I-8-C indicated that the eight-class model based on MobileNetV1 had better performance than the one based on InceptionV3. An optimized model, namely M-8f-C, was developed based on M-8-C and was successfully mounted on mobile phone. The field tests showed that M-8f-C was of decent performance under field conditions.Conclusion Classifier based on deep learning and transfer learning has high accuracy for recognizing HLB symptom leaves.

Abstract:Objective In order to solve the problems of complex and variable gear parts and low knowledge reuse rate in the process of virtual design and simulation of agricultural gearboxes. Method Based on the classification of gearbox gear knowledge, the ontology was used to describe the gear design knowledge. Combining knowledge engineering and parametric design technology, a knowledge-based virtual gear design method was proposed. This system was verified using the complex spline gear design of tractor gearbox as an example. Result A virtual design system for gearbox gear was developed using the three-dimensional modeling software NX as a platform. The gear design requirements were obtained through the human-machine system interface. With the support of gear design knowledge base and model library, the gear structure was inferred using knowledge reuse. Driven by the geometric parameters, a gear model that met the design requirements was quickly constructed to achieve the rapid and intelligent design of gears with complex structures. The verification results showed that the system could automatically output the detailed spline gear structure model in seconds when entering the design requirements in the man-machine interface. Conclusion This system can better support the virtual design and simulation of gearbox, shorten the development cycle of agricultural machinery, and also provide a technical reference for the virtual design of other mechanical product.

Abstract:Objective To solve the problem of traversal path planning of agricultural robot in field operation.Method A memory simulated annealing algorithm combined with A* algorithm was proposed. Firstly, the optimal walking sequence of target points in task was found by memory simulated annealing algorithm, and then A* algorithm was used for crossing regional linking of path planning.Result The simulation experiments showed that the Manhattan distance of traversal path planned by this algorithm was reduced by 9.4% compared with the traditional simulated annealing algorithm, the coverage of traversal path could reach 100%, and the repetition rate could be controlled at 4.2%.Conclusion Memory simulated annealing algorithm enhances the ability to jump out of the local optimal trap, and improves the quality of the solution obtained by adding memory device to the traditional simulated annealing algorithm. The research results can provide a theoretical basis for the path planning of agricultural robot.