• Volume 42,Issue 4,2021 Table of Contents
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    • Alternations of mammary gland morphology, and marker protein expression, related hormones and signaling pathways of mammary gland development during gestation in Tibetan pigs

      2021, 42(4):1-6. DOI: 10.7671/j.issn.1001-411X.202010013

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      Abstract:Objective To investigate the alternations of the mammary gland morphology and of the marker protein expression, related hormones and signaling pathways of mammary gland development during gestation in Tibetan pigs.Method The pigs were slaughtered, and serum and the mammary glands of the third and fourth pairs were collected at 33, 50, 75 and 90 days of gestation. HE staining was used to observe the changes in mammary gland morphology. The ELISA kit was used to detect the serum levels of hormones related to mammary gland development such as estradiol (E2), progesterone (P) and prolactin (PRL). Western blot method was used to examine the expressions of marker proteins such as E74-like factor 5 (Elf- 5) and perilipin 2(PLIN2) in mammary gland development, and of hormone receptors such as estrogen receptor (ERα), prolactin receptor (PRLR) and progesterone receptor (PR), as well as the activations of PI3K/AKT and Jak2/STAT5 signal pathways which were related to mammary gland development.Result Morphologically, the mammary glands at 33 days of gestation were mainly composed of ductal structures, and a small amount of alveolar structures appeared at 50 days. At 75 days, the alveoli developed rapidly in the mammary glands. Notably, the mammary glands were mainly composed of alveolar structures at 90 days. Correspondingly, the expression levels of the marker proteins Elf-5 and PLIN2 in mammary gland development began to increase at 50 days of gestation, with high expression levels at 75 and 90 days. Meanwhile, serum levels of E2, P and PRL all increased with the progress of gestation. The contents of E2, P and PRL reached 42.82 ng/L, 36.76 and 66.53 μg/L respectively at 90 days. In addition, the expression levels of ERα and PRLR increased at 50 days and the PR expression increased at 75 days. Furthermore, the Jak2/STAT5 and PI3K/AKT signaling pathways were significantly activated at 75 and 90 days of gestation.Conclusion During gestation in Tibetan pigs, the mammary glands begin to develop alveolar at 50 days, enter the rapid alveolar development stage at 75 days, with higher developmental degree at 90 days. The alternations of mammary gland morphology are accompanied with the significant increase of hormones related to mammary gland development in serum and of hormone receptor expression in mammary glands, and with the activations of the PI3K/AKT and Jak2/STAT5 pathways which are closely related to mammary gland development.

    • Isolation and identification of Mangshi virus in sentinel cattle from border areas of Yunnan Province

      2021, 42(4):7-16. DOI: 10.7671/j.issn.1001-411X.202007009

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      Abstract:目的 掌握云南省边境地区动物虫媒病毒的多样性分布和传播风险。方法 在云南省景洪市设立哨兵牛3头,每周1次采血进行虫媒病毒的监测与分离。通过电镜观察、基因组琼脂糖凝胶电泳、RT-PCR与克隆测序对分离病毒进行鉴定,采用实时荧光定量RT-PCR与血清中和试验对病毒在动物上的感染进行回溯分析。结果 2019年,在监测期第13周,从1头哨兵牛的血液中分离出1株致C6/36细胞病变的病毒(V301/YNJH/2019),电镜观察可见直径约70 nm、呈二十面体对称结构的病毒粒子,琼脂糖凝胶电泳显示病毒基因组为双链RNA,RT-PCR鉴定分离毒株为芒市病毒(MSV)。测序显示,分离毒株的基因节段Seg-4和Seg-7长度为2 055和1 122 bp,编码病毒的外层衣壳蛋白VP4(628 aa) 和VP7(298 aa),基因节段Seg-2和Seg-9长度为3 055和1 076 bp,编码病毒的内层衣壳蛋白VP2(956 aa) 和VP9(283 aa);分离毒株与云南省芒市分离的MSV/DH13M041毒株具有最近的亲缘关系,核酸序列相似度在97.4% (Seg-9)~98.5% (Seg-2)之间,氨基酸序列相似度在96.4%(VP9)~98.4%(VP2)之间。病毒感染的回溯分析显示,监测期的第11周,牛血液中病毒核酸检测呈阳性,病毒核酸含量在第13周达到高峰,随后快速降低,在第18周转为阴性;感染哨兵牛在监测期的第13周已产生特异性中和抗体(1∶14),在第16~18周处于高峰(1∶226),至监测结束的第24周降低为1∶57。结论 本文从牛体中分离到了MSV,表明牛是MSV的易感动物之一,病毒在感染牛上呈“一过性感染”的特征。研究结果为进一步开展MSV的检测诊断、流行病学调查与致病性研究奠定了基础。

    • Effects of straw returning combining with sulfur fertilizer on yield, sulfur accumulation and distribution in spring maize

      2021, 42(4):17-24. DOI: 10.7671/j.issn.1001-411X.202010015

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      Abstract:Objective To explore the effects of straw returning combining with sulfur fertilizer on the yield and sulfur accumulation, distribution and transportation of spring maize, and provide theoretical bases for exploring the accumulation and transportation laws of sulfur fertilizer in spring maize as well as rational application of sulfur fertilizer.Method Two-factor split block design was used, the main plot was divided into straw returning and no straw returning, the subplot was divided into sulfur fertilizer application and no sulfur fertilizer, which formed five treatments of CK (no fertilizer), no straw returning and no sulfur fertilizer, no straw returning and sulfur fertilizer, straw returning and no sulfur fertilizer, straw returning and sulfur fertilizer. The effects of straw returning combining with sulfur fertilizer application on the accumulation, distribution and transportation of sulfur in spring maize were studied through the field experiment.Result Straw returning combining with sulfur fertilizer had a certain degree of increasing the yield. The maize yield of straw returning and sulfur fertilizer was 11.98% higher than that of straw returning and no sulfur fertilizer, and 20.34% higher than that of no straw returning and no sulfur fertilizer. Straw returning combining with sulfur fertilizer could significantly increase the accumulation of sulfur in spring maize. The sulfur accumulation amount of straw returning and sulfur fertilizer was 13.37% higher than that of no straw returning and sulfur fertilizer, and 52.67% higher than that of no straw returning and no sulfur fertilizer. Sulfur fertilizer application could increase the accumulation of sulfur in plant organs. The sulfur accumulation amount of sulfur fertilizer application treatment was averagely 36.07% higher than that of no sulfur fertilizer application treatment. The sulfur accumulation amount in each organ generally behaved as grain > leaf > stem > ear. Compared with the treatment of no straw returning and no sulfur fertilizer, total sulfur transport amount of straw returning and sulfur fertilizer treatment increased by 74.54%, reaching the highest of 15.29 kg·hm?2, and total contribution rate of sulfur transport amount to grain increased by 17.27%.Conclusion Straw returning combining with sulfur fertilizer can promote the accumulation of sulfur in spring maize and the transportation of sulfur from vegetative organs to grains, and ultimately improve the yield of spring maize.

    • Analyses of Ipomoea batatas cultivated species and wild relatives based on mtDNA and cpDNA sequences

      2021, 42(4):25-32. DOI: 10.7671/j.issn.1001-411X.202011026

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      Abstract:Objective To conduct molecular identification and genetic relationship analysis of Ipomoea batatas cultivated species and wild relatives based on mitochondrial DNA (mtDNA) and chloroplast DNA (cpDNA) matK sequences, and provide theoretical bases for germplasm identification, protection, development and utilization.Method Three cultivated species and eight wild relatives were used as materials, from which total DNA was extracted by the CTAB method. Their mtDNA and cpDNA matK sequences were amplified by PCR. DnaSP 6.0 was used to analyze nucleotide diversity, haplotype diversity and other characteristics. The phylogenetic tree of three cultivated species and eight wild relatives was constructed based on the neighbor-joining method.Result The length of five mtDNA regions and one cpDNA region was 6 713 bp after sequencing, alignment and splicing, the GC proportion was 47.79%−48.31%, and the haplotype number, nucleotide diversity, variable site number, singleton variable site number, parsimony informative site number, insertion/deletion site number were 9, 0.003 25, 69, 39, 30, 111, respectively. The neutrality test showed there was no significant difference between Tajima’s D values at the level of P>0.10, which indicated that variation of those regions followed neutral theory of molecular evolution. The genetic distances among three cultivated species and eight wild relatives ranged from 0.000 00 to 0.005 84, with an average genetic distance of 0.003 26, indicating low genetic diversity. The phylogenetic tree divided the 11 species into two categories with close genetic relationship within the category.Conclusion The sequences used in this study can accurately identify I. batatas cultivated species and wild relatives, and provide references and theoretical guidance for the evolution and utilization of I. batatas wild relatives.

    • Function of GmPIN2b in soybean regulating root response to low phosphorus stress

      2021, 42(4):33-41. DOI: 10.7671/j.issn.1001-411X.202010014

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      Abstract:Objective To study the function of auxin transporter PIN gene family in the adaptation of soybean (Glycine max) roots to low phosphorus stress.Method A total of 23 GmPIN family members of soybean were conducted evolutionary tree and expression pattern analyses, so as to analyze the GmPIN2b function.Result The 23 GmPIN family members of soybean were scattered in seven different sub-families, among which GmPIN2a, GmPIN2b and GmPIN9a, GmPIN9d were in the same subfamily as Arabidopsis thaliana AtPIN2. Different GmPIN family members had different tissue expression locations in soybean and their expression patterns regulated by low phosphorus were different. Among them, the expression level of GmPIN2b in soybean roots was significantly up-regulated after low phosphorus stress for six days. The complement expression of GmPIN2b could partially restore the phenotype of Atpin2 mutants. The fresh weight and main root length of transgenic plants expressing GmPIN2b were significantly higher than those of Atpin2 mutant under both low or high phosphorus conditions. Moreover, the complement expression of GmPIN2b also significantly increased the number of primary lateral roots of Atpin2 mutant in low phosphorus treatment, and increased the sensitivity of the root system to gravity in high phosphorus treatment.Conclusion GmPIN2b plays an important regulatory role in the process of root morphogenesis in response to low phosphorus stress.

    • Effects of inoculating arbuscular mycorrhizal fungi on growth and phosphorus uptake of soybean under low phosphorus conditions

      2021, 42(4):42-50. DOI: 10.7671/j.issn.1001-411X.202010024

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      Abstract:Objective To illuminate the response of different P-efficient soybean genotypes to arbuscular mycorrhizal fungi inoculation at different growth stages and the relationship with P efficiency, and provide a theoretical basis for research of arbuscular mycorrhizal fungi inoculation improving crop P efficiency.Method The experiments were conducted using three soybean genotypes of ‘Weilianmusi 82’ ‘Yuechun 04-5’ and ‘Baxi 10’ under mycorrhizal and non-mycorrhizal inoculation treatments at flowering and podding stages. The effects of arbuscular mycorrhizal fungi inoculation on soybean plant dry weight, arbuscular mycorrhizal colonization rate, P nutrition status, root traits, and expression of arbuscular mycorrhizal inducible phosphate transporter genes were analyzed.Result The mycorrhizal responses of different soybean genotypes to arbuscular mycorrhizal fungi inoculation were significantly different at different growth stages. Compared with non-mycorrhizal inoculation treatment, the inoculation treatment significantly improved the expression levels of three arbuscular mycorrhizal inducible P transporter genes of GmPT8, GmPT9 and GmPT10 in the roots of three soybean genotypes at flowering stage, which resulted in the significant increase of P concentrations in roots of these three soybean genotypes, and the inoculation treatment significantly improved the root dry weight of these three soybean genotypes, as well as shoot dry weight, P concentration and total P uptake amount of ‘Baxi 10’ at podding stage. At flowering stage, non-mycorrhizal ‘Weilianmusi 82’ and ‘Yuechun 04-5’ plants had significantly higher shoot dry weight, total P uptake, total root length and root surface area than ‘Baxi 10’, while mycorrhizal growth response and mycorrhizal P response of arbuscular mycorrhizal fungi inoculated ‘Baxi 10’ were significantly higher than those of ‘Weilianmusi 82’ and ‘Yuechun 04-5’.Conclusion ‘Weilianmusi 82’ and ‘Yuechun 04-5’ have higher P efficiency, while ‘Baxi 10’ has higher mycorrhizal dependence. The prolonged growth period from flowering stage to podding stage promotes the transformation of acquired P by mycorrhizal plants into biomass, which further stimulates the beneficial symbiosis between soybean and arbuscular mycorrhizal fungi.

    • Identification of an antagonistic strain Bacillus amyloliquefaciens E3 against Dickeya zeae and its antimicrobial activity

      2021, 42(4):51-62. DOI: 10.7671/j.issn.1001-411X.202009039

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      Abstract:目的 纯化和鉴定从柑橘根际土壤分离得到的可抑制水稻基腐病菌Dickeya zeae EC1生长的解淀粉芽孢杆菌Bacillus amyloliquefaciens,并解析其抑菌机制。方法 采用平板扩散法从根际土壤中筛选出1株拮抗D. zeae EC1的B. amyloliquefaciens E3菌株;根据细菌菌落表型、生理生化特征结合16S rDNA序列分析等方法对E3菌株进行分类鉴定;检测无菌E3培养液对D. zeae EC1侵染水稻种子能力的影响;盐酸沉淀结合丙酮抽提法提取E3菌株脂肽粗提物;采用平板对峙法测定E3菌株脂肽粗提物对病原真菌的抑菌活性,琼脂扩散法测定E3菌株脂肽粗提物对病原细菌的抑菌活性及最小抑菌浓度(Minimum inhibitory concentration, MIC);用Durashell C18柱对脂肽粗提物进行HPLC分离纯化;通过液相色谱−质谱联用(LC-ESI-MS)分析,鉴定抑菌物质的相对分子质量并推测其化学组成。结果 B. amyloliquefaciens E3菌株对茄病镰刀菌Fusarium solani、香蕉基腐病菌、茄科劳尔氏菌Ralstonia solanacearum等多种植物病原菌生长具有抑制作用,表现为广谱抗性;B. amyloliquefaciens E3菌株的无菌培养液能够抑制D. zeae EC1侵染萌发的水稻种子,显著提高水稻种子的萌芽率;B. amyloliquefaciens E3菌株的脂肽粗提物可以抑制D. zeae EC1的生长,其MIC为348.97 μg/mL;HPLC分离纯化结合LC-ESI-MS分析发现,B. amyloliquefaciens E3菌株分泌的主要抑菌活性物质包括Surfactin、Fengycin和Iturin 3类脂肽类抗生素。结论 B. amyloliquefaciens E3菌株具有作为生防菌的潜力,它可能通过分泌Surfactin、Fengycin和Iturin 3种脂肽类抑菌活性物质,拮抗水稻基腐病菌、茄科劳尔氏菌、茄病镰刀菌等多种植物病原菌。研究结果可为该菌的生物防治应用提供理论依据。

    • Pathogen identification of anthracnose disease on Millettia speciosa and indoor determination of fungicide toxicity

      2021, 42(4):63-69. DOI: 10.7671/j.issn.1001-411X.202012008

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      Abstract:Objective To determine the pathogen causing anthracnose disease on Millettia speciosa and screen effective fungicides.Method Tissue isolation method was used to isolate the pathogen. The pathogenicity was tested according to Koch’s rule after purification. The pathogen was identified based on morphological characteristics and multi-locus sequence analysis. Furthermore, the sensitivity of this pathogen against four common fungicides was measured according to the mycelial growth rate.Result Two out of six obtained isolates could infect M. speciosa leaf and caused brown spot. Combining morphological characteristics and multi-locus sequences analysis, the pathogen caused anthracnose disease on M. speciosa was identified as Colletotrichum siamense. This pathogen was highly sensitive to difenoconazole, prochloraz, pyraclostrobin and thiophanate-methyl with EC50 values below 0.1 mg/L, and prochloraz showed the highest efficacy with EC50 of 0.015 mg/L.Conclusion The pathogen causing anthracnose disease on M. speciosa is C. siamense, and difenoconazole, prochloraz, pyraclostrobin and thiophanate-methyl can be applied to control anthracnose disease in the field.

    • Development of a molecular marker for sex identification of Spodoptera frugiperda

      2021, 42(4):70-74. DOI: 10.7671/j.issn.1001-411X.202012033

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      Abstract:Objective To develop molecular marker primers for sexual identification of Spodoptera frugiperda.Method Based on the difference in pheromone-binding protein (PBP) gene sequences of male and female S. frugiperda, the primers were designed for distinguishing sexual distinction specifically. Using the primers, the male and female S. frugiperda samples already identified by morphology were further verified by PCR.Result Specific bands of about 450 bp for the corresponding female and male samples were amplified by two pairs of primers respectively.Conclusion The molecular marker primers can be used to discriminate the sex of S. frugiperda in various developmental stages efficiently, and provide an effective tool for the study of the individual distinction between different sexual insects. This study provide a reference for formulating the strategy to control S. frugiperda effectively based on sexual distinction.

    • Biodiversity of Isaria in soil and its activity against Phyllotreta striolata

      2021, 42(4):75-82. DOI: 10.7671/j.issn.1001-411X.202012012

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      Abstract:Objective To investigate the diversity of Isaria from different soils in some areas of China, and to determine their bioactivity against Phyllotreta striolata, so as to promote the application of Isaria as biocontrol agents.Method Soil samples were collected from different habitats in Fujian, Guangdong, Yunnan, Guizhou, Hunan, Hubei, Henan, Hebei and Guangxi Provinces (Regions). Isaria strains were isolated and purified by selective medium, and identified based on morphology and molecular markers. The Shannon-Weiner and dominance indexes were used to evaluate the biodiversity. The biological activities of Isaria strains against P. striolata were determined by immersion method.Result A tatol of 41 Isaria strains were isolated from more than 200 soil samples. The dominant species was I. javanica with 34 strains and a dominance index of 0.829. Meanwhile, five strains of I. fumosorosea, one strain of I. farinosa and one strain of I. cateniannulate were isolated. The woodland habitat had the highest biodiversity for Isaria with Shannon-Wiener index of 1.121, followed by fallow land, orchard, farmland, grassland with the Shannon-Wiener indexes ranged from 0 to 0.349. Woodland habitat had the most uniform distribution among species, with the dominance index of 0.468, and the dominance indexes of fallow land, orchard, farmland and grassland ranged from 0 to 0.159. The results of bioassay showed that most tested strains had certain activity against P. striolata. The strain IfH6102 had the highest activity with the corrected mortality of 60.89% at 11 days after treatment.Conclusion Isaria is widely distributed in the soil of China. The woodland has the highest biodiversity for Isaria, and Isaria has the potential to be used for controlling P. striolata.

    • Response of growth and branch development of Betula alnoides young plantation to light environment

      2021, 42(4):83-88. DOI: 10.7671/j.issn.1001-411X.202011003

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      Abstract:Objective A canopy shading experiment was conducted by simulating the light environments of plantations with a series of planting densities, to explore the effects of light environments on tree growth and branch development, and provide a theoretical guidance for the efficient cultivation of large-sized and high quality timber of Betula alnoides through reasonable arrangement of planting density.Method On the basis of a series of afforestation density tests, three shading treatments (40%–45%, 55%–60% and 80%–90% shade rate) with 2/3 of the lower crown shaded and one control (CK) of no shade were set in plots with planting density of 4 m×4 m from a 5-year-old planting density trail of B. alnoides in early October following the local phenology of this species. The dominant tree and the subdominant tree were selected as experiment objects. The tree growth and branch development of all treated individuals were investigated every three or six months.Result The increments of tree height and diameter at breast height (DBH) in each interval and the whole experimental period did not differ significantly among shading treatments (P≥0.05). DBH increment was the highest from January to April, and exceeded 0.73 cm in each treatment. However, branch development in each interval and the whole experimental period was significantly affected by shading (P<0.05), excepting branch length growth from April to July in 2018. Both the increments of branch diameter and length decreased significantly with the increase of shading rate, and the increasing trend was more significant in fast-growing season (from January to April), in which the increments of branch diameter and length of CK was 1.74 and 1.78 times higher than those of 80%–90% shade rate treatment, and reached 1.197 mm and 0.135 m, respectively. Moreover, the natural pruning rate of B. alnoides young plantations also showed an obvious increasing trend with the increase of shading rate, and the natural pruning was focused from April to July with pruning rate increment over 47%.Conclusion The low light environment caused by appropriate high planting density almost has no significant effect on the individual growth of B. alnoides, while it can efficiently control branch development and promote natural pruning. The planting with an appropriate high density would be beneficial for large-sized and high quality timber cultivation of B. alnoides in practice.

    • Influence of crosswind on droplet drift of flat-fan nozzle in aviation plant protection UAV

      2021, 42(4):89-98. DOI: 10.7671/j.issn.1001-411X.202105025

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      Abstract:Objective Crosswind is the main factor affecting droplet drift and spraying effect of aerial spraying for plant protection unmanned aerial vehicle (UAV). To explore the influence of crosswind on droplet deposition and drift during aerial spraying, and provide data support and theoretical guidance for selection of operation parameters and improvement of key components of aerial spraying for plant protection UAV.Method Lechler series LU 120-015 and LU 120-03 standard fan-shaped pressure nozzles were taken as the research objects. Based on the particle tracking technology of computational fluid dynamics (CFD) discrete phase model, the simulation tests of droplet flow field and pesticide spraying discrete phase in the wind tunnel were carried out under suitable boundary conditions. Through the simulation, the deposition and drift distribution of droplets sprayed by fan nozzle were analyzed visually to explore the drift characteristics of droplets at different lateral wind speeds. The deposition and drift characteristics of droplets were tested and analyzed in the agricultural aviation special wind tunnel under the similar conditions.Result The simulation results showed that the drift degree of discrete phase droplets was more serious and the horizontal drift of droplets was more obvious with the increase of lateral wind speed. With the increase of lateral wind speed, the accurate deposition rate (Ra) decreased exponentially from 14.11% to 0.66%, and the horizontal drift rate (Rh) increased linearly from 14.25% to 60.58%. The wind tunnel test results showed that the Rh values of droplets were 0.4%, 48.1% and 75.1% at the lateral wind speeds of 1, 3 and 6 m/s respectively, and the droplets appeared the winding phenomenon to a certain extent in the wind tunnel. The results of correlation analysis showed that there was a significant correlation between the horizontal drift rates of computer simulation and wind tunnel test, and the R2 was 0.963 (P<0.05).Conclusion The simulation test has a good prediction effect on droplet drift under aerial spraying condition. The simulation-assistanted wind tunnel test method can get a reasonable result of the droplet deposition and drift of the flat-fan nozzle commonly used in aviation plant protection operation.

    • Optimization design and test of seed protecting structure of combined type-hole metering device

      2021, 42(4):99-105. DOI: 10.7671/j.issn.1001-411X.202106022

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      Abstract:Objective In order to solve the problems that the seed guard belt is easy to deviate and slip in application of the combined type-hole metering device of rice precision hole seeder, which leads to serious wear of the seed guard belt and high rate of seed damage.Method The synchronization principle of seed protection mechanism was analyzed, and the shaft sleeve structure(A) and the hardness of seed guard belt(B) were optimized. A two-factor experiment with different bushing structures (A1 as nylon bushing structure, A2 as needle bearing & copper bushing structure) and hardness of seed guard belt (B1, B2, B3, B4 and B5 represented the hardness of 40, 45, 50, 55 and 60 HA, respectively) was designed using rice variety ‘Peizataifeng’ and ‘Xiushui134’ seeds as test materials.Result The experimental groups of A and B had the highly significant effect on the damage rate of rice seeds (P < 0.01), and there was a significant interaction between A and B (P < 0.05). A2B2 and A2B3 had the least effect on seed damage rate. There was a highly significant difference between A1 and A2, and seed damage rate of A2 was significantly lower than that of A1, indicating that A2 was better than A1. There was no significant difference between B2 and B3, but B2 and B3 had significant difference with other groups. The experimental group A had a significant effect on hill diameter, B had no significant effect on hill diameter, and the groups of A2B2, A2B3 and A2B4 had the less effect on hill diameter. There was a significant difference between A1 and A2, and A2 was significantly better than A1.The results of test showed that the wear of seed guard belt of A2B3, A2B4 and A2B5 were less after working for 100 hour. The grouo A2B3 was the optimal with the wearing volume of 72.6×10?3 mm3 and seed injury rate of 0.04%, and the hole forming ability and sowing effect were both the best.Conclusion The optimized design of needle bearing & copper bushing shaft sleeve structure is reasonable. It can significantly reduce the friction coefficient between sleeve and shaft, is more resistant to high temperature and wear resistance, effectively improves the synchronization of seed guard belt, and significantly improves the reliability and sowing quality of seed platter.

    • Simulation study on the influence of trickle laterals equipped with integrated in-line and out-line emitters on the hydraulic characteristics

      2021, 42(4):106-112. DOI: 10.7671/j.issn.1001-411X.202009004

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      Abstract:Objective To study the influence of emitter mosaic mode on the hydraulic characteristics of trickle laterals.Method Two kinds of trickle laterals equipped with integrated in-line emitters and one trickle lateral equipped with integrated out-line emitters were tested. At the same time, three kinds of trickle laterals were simulated and verified by computational fluid dynamics (CFD) method. On this basis, the head loss and laying length of trickle laterals equipped with integrated in-line and out-line emitters under different discharge were simulated and calculated.Result The simulated values of the total head loss of trickle laterals equipped with integrated in-line and out-line emitters were slightly lower than the measured values, and the relative deviation between the simulated and measured values of trickle laterals equipped with integrated out-line emitters was smaller. The drip head embedding mode had a significant influence on the hydraulic characteristics of trickle laterals. Compared with trickle laterals equipped with integrated in-line emitters, the total head loss of trickle laterals equipped with integrated out-line emitters was smaller, with the reduction ratio of the total head loss exceeding 49.2%, and the reduction ratio of the total head loss gradually increased with the increase of the drip head flow. The maximum laying length of trickle laterals equipped with integrated out-line emitters was longer than that of trickle laterals equipped with integrated in-line emitters, and the length increased by 21.6% to 56.9%. The main reason for the greater total head loss of trickle laterals equipped with integrated in-line emitters was that the pressure gradient of trickle laterals equipped with integrated in-line emitters consumes a large amount of water flow energy due to the redistribution of the flow velocity in the section.Conclusion The hydraulic performance of trickle laterals equipped with integrated out-line emitters is better than that of trickle laterals equipped with integrated in-line emitters. For the design of long distance economic crop drip irrigation system, trickle laterals equipped with integrated out-line emitters can be given priority.

    • Recognition of mango fruit diseases based on image processing and deep transfer learning

      2021, 42(4):113-124. DOI: 10.7671/j.issn.1001-411X.202011002

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      Abstract:Objective To realize non-destructive detection of the internal quality of mangoes and disease identification and classification based on the CT sequence images of mangoes obtained by computed tomography (CT) equipment.Method We used piecewise function method and median filter combined with bilateral filter to achieve image enhancement, used local adaptive threshold method to achieve binarization processing, used seed filling method to perform area filling, and used the image difference method to accurately extract the damaged area in inner tissue of mango fruit. Based on the deep transfer learning model, training and testing were carried out on unprocessed and processed mango image data. Transfer learning was carried out through the AlexNet and GoogLeNet deep learning networks, and hyperparameters were adjusted to complete the network fine-tuning of the training process. Under different models, the classification results of unprocessed and processed mango test sets on the model were compared.Result Based on the unprocessed data set, the GoogLeNet model was trained at a learning rate of 0.0002, and the Accuracy and Macro-average were 98.79% and 98.41% respectively. Based on the processed data set, the GoogLeNet model was trained at a learning rate of 0.0002, and the Accuracy and Macro-average were 100% and 100% respectively. The deep transfer learning model had a greater improvement in the model classification index of the processed data set than the unprocessed data set. Based on the same data set and consistent hyperparameters, the classification effect of the GoogLeNet network was significantly better than that of the AlexNet network.Conclusion While learning rate is set to 0.0002, the Epoch value is 3, and the Mini Batch value is 64, deep transfer learning training is carried out based on the GoogLeNet network, and the resulting model is used as the final classification model.

    • Classification of fresh tea leaf based on random forest model by feature fusion

      2021, 42(4):125-132. DOI: 10.7671/j.issn.1001-411X.202012006

      Abstract (766) HTML (648) PDF 1.94 M (1135) Comment (0) Favorites

      Abstract:Objective To solve the problems of the machine-picked fresh tea leaves mixing with different grades of tea leaves, high mixing degree and low classification accuracy of physical characteristics.Method Using the random forest classification model, a method based on the fusion of color and edge feature was proposed. We collected three different grades of fresh tea leaves, and processed the original images with cropping, size normalization and denoising, and then extracted the color features and edge features. Through parameter modification and testing, the optimal random forest classification model was constructed, and the comparison experiment was performed with the K-nearest neighbor and SVM classifier.Result After feature fusion, the classification accuracy of random forest model reached 99.45%, which was 7.14 and 9.34 percentage points higher than those of single color feature and single edge feature, 15.38 and 5.49 percentage points higher than those of K-nearest neighbor model and SVM classifier respectively.Conclusion The established method can accurately separate single bud, one bud and one leaf, and one bud and two leaves of fresh tea leaves.