• Volume 38,Issue 5,2017 Table of Contents
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    • Effects of different concentrations of amino acids on urea cycle in primary porcine hepatocytes

      2017, 38(5):1-6. DOI: 10.7671/j.issn.1001-411X.2017.05.001

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      Abstract:[Objective] To investigate the effects of different concentrations of amino acids on urea cycle in primary hepatocytes isolated from piglet, and explore the potential mechanism.[Method] Primary hepatocytes isolated from 5-day old piglet were cultured in medium containing different concentrations of amino acids (AA)(1, 2, or 4 times of physiological concentration in serum). After 24 h, the supernatant and cells were collected. Urea and ammonia concentrations in the supernatant, glutaminase(GLS) and glutamine synthetase(GS) activities and ammonia concentration in cells were examined by colorimetry. The mRNA expression of genes involved in urea cycle, including carbamyl phosphate synthetase 1(CPS1), Argininosuccinate synthetase(ASS), Argininosuccinate lyase(ASL), Omithine transcarbamylase (OTC), Arginase (ARG) were detected by qRT-PCR.[Result] Urea and ammonia concentrations in the supernatant, and GLS activity in cells were significantly elevated in 4×AA group. Meanwhile, 4×AA remarkably increased the mRNA expression of CPS1, ASS and ASL genes in hepatocytes. NH4Cl at 1.0 and 2.0 mmol·L–1 concentrations significantly promoted urea synthesis in the cell.[Conclusion] High concentration of AA might accelerate ammonia accumulation by GLS and enhance the expression of the urea cycle enzymes (CPS1, ASS and ASL), which contribute to increased production of urea.

    • Effects of glutathione on proliferation and biochemical function of primary hepatocyte in hybrid tilapia (Oreochromis niloticus×O. aureus)

      2017, 38(5):7-12. DOI: 10.7671/j.issn.1001-411X.2017.05.002

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      Abstract:[Objective] To investigate the effects of glutathione (GSH) on proliferation and biochemical function of primary hepatocyte in hybrid tilapia (Oreochromis niloticus×O. aureus).[Method] Tilapia primary hepatocytes were cultured in cell culture medium with 0 or 10% fetal calf serum for 48 h. GSH was then added into the two kinds of cell culture medium to the final concentration of 0, 30, 100, 300 or 900 mg·L–1 respectively. Each concentration group had six replicates. The proliferation status of the primary hepatocyte, contents of insulin-like growth factor 1 (IGF-1), albumin and H2O2, as well as glutamate-oxaloacetate transaminase (GOT) and γ-glutamyl transpeptidase (γ-GT) activities of tilapia were detected after cultured for 24, 48 and 72 h, respectively.[Result] GSH significantly increased the proliferation of primary hepatocyte,the contents of IGF-1 and albumin,and γ-GT activity in supernatant,while reduced H2O2 content and GOT activity(P<0.05). Such effects of GSH were more evident in the group without fetal calf serum compared to the group with 10% fetal calf serum.[Conclusion] GSH could enhance the proliferation of primary hepatocyte and has the function of protecting liver in hybrid tilapia.

    • Analysis of genetic information in HA genes and antigen specificities of three strains of H1N1 swine influenza virus

      2017, 38(5):13-18. DOI: 10.7671/j.issn.1001-411X.2017.05.003

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      Abstract:[Objective] To study the genetic information in HA genes and antigen specificities of SWSS1, SWL6 and Pdm091057 strains which respectively belongs to Eurasian avaian-like, classical and Pdm09H1N1 branches of H1N1 swine influenza viruses (SIV), and provide a basis for functional study on antigenic epitopes of HA gene as well as prevention and control of influenza virus.[Method] We compared the genetic information in HA gene fragments of three H1N1 subtypes, SWSS1, SWL6 and Pdm091057. Inactivated SIV vaccines were prepared and each type of vaccine was used to immune three New Zealand white rabbit. The hemagglutination inhibition (HI) reaction was used to detect antibody titers.[Result] The amino acid sequences of HA gene fragments had 69.4%–89.1% similarities among three SIV strains. There were variations in antigenic epitopes of HA genes of the three strains. The average HI antibody titers were all above 1 280 for three strains after the second immunization, and the average HI antibody titer for SWSS1 reached 2 560. SWSS1 had no serological cross reaction with SWL6 or Pdm091057 strain, while SWL6 and Pdm091057 strains had low degree of serological cross reaction.[Conclusion] Three SIV strains have differences in antigenic epitopes of HA gene, which may be the reason for the low degree of serological cross reaction among strains. All three strains have good immunogenicity, and can be used as candidate vaccine strains.

    • Prokaryotic expression and activity detection of bacteriophage lysin Cp51 against Clostridium perfringens type A

      2017, 38(5):19-23. DOI: 10.7671/j.issn.1001-411X.2017.05.004

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      Abstract:[Objective] To construct a prokaryotic expression system of type A Clostridium perfringens phage lysin Cp51, and study its antibacterial activity against C. Perfringens type A in vitro.

      [Method] Bacteriophage lysin Cp51 gene was synthesized. The prokaryotic expression vector pET-32a-Cp51 was constructed and transformed into Escherichia coli BL21(DE3). After induction using 0.5 mmol·L–1 IPTG, the soluble recombinant protein Cp51 was successfully expressed, and was subsequently purified with Ni2+-NTA affinity chromatography. The antibacterial activity of the recombinant protein Cp51 was detected by kinetic turbidimetric assay.[Result] The bacteria turbidities of seven strains of C. perfringens type A were effectively reduced by the recombinant protein Cp51. The bactericidal rate was above 99.99% in 30 min after treatment of recombinant protein Cp51 at the concentration of above 5 μg·mL–1. The Cp51 protein had no bactericidal effect against other types of bacteria.[Conclusion] The recombinant protein of bacteriophage lysine Cp51 has strong bactericidal activity and specificity in vitro against type A C. perfringens, which could provide a basis for clinical application of Cp51 lysin.

    • Effects of anoxic and aerobic cultivation conditions on cadmium accumulation and OsHMA2 expression in rice

      2017, 38(5):24-29. DOI: 10.7671/j.issn.1001-411X.2017.05.005

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      Abstract:[Objective] To study the effects of anoxic and aerobic cultivation conditions on cadmium (Cd) uptake and transfer and OsHMA2 expression in rice shoots, and provide a theoretical basis for reducing the uptake and accumulation of heavy metals in rice.[Method] Using rice cultivar ‘Wufengyou 2168’, pot experiments were performed hydroponically under anoxic(nutrient solution with agar) and aerobic(oxygenized nutrient solution) conditions. Cd uptake and accumulation, and OsHMA2 expression levels in rice shoots were analyzed at three Cd levels(0, 0.6, 1.2 mg·L–1).[Result] Rice growth was not significantly inhibited by Cd under anoxic condition, but was significantly inhibited under aerobic condition with the dry weight of roots and above ground parts significantly decreased. At the Cd concentration of 0.6 and 1.2 mg·L–1, Cd accumulations in roots and above ground parts of rice under anoxic condition were lower than those under aerobic condition. Under both anoxic and aerobic conditions, Cd accumulation in roots increased with Cd concentration. For above ground parts of rice, Cd accumulation was not significantly different between 0.6 and 1.2 mg·L–1 Cd levels under anoxic condition, but increased with Cd concentration under aerobic condition. Compared with the control (0 mg·L–1 Cd), OsHMA2 expression level increased at the Cd concentration of 0.6 mg·L–1 but decreased at 1.2 mg·L–1 in shoots under both anoxic and aerobic condition, and OsHMA2 expression level in rice was higher under anoxic condition than those aerobic condition at each Cd level.[Conclusion] Anoxic culture can inhibit Cd uptake and accumulation in rice, and OsHMA2 expression decreases when Cd accumulation reaches a certain value.

    • Effects of various low-molecular-weight organic acids on phosphorus transformation in lateritic soil

      2017, 38(5):30-35. DOI: 10.7671/j.issn.1001-411X.2017.05.006

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      Abstract:[Objective] To reveal the action mechanisms of organic acids, and provide a scientific basis for raising the utilization rate of accumulative phosphorus(P) in acidic red soil.[Method] Laboratory simulation experiments were conducted to study the effects of low-molecular-weight organic acids, represented by oxalic acid, citric acid and malic acid, on P form in lateritic soil.[Result] SDuring the whole incubation period, citric acid inhibited resin-P(P1) desorption, while water (control), oxalic acid and malic acid enhanced resin-P(P1) desorption. At the earlier stage of incubation, all three organic acids inhibited the activation of NaHCO3-extractable inorganic P(P2), with citric acid having the highest inhibition effect and oxalic acid having the lowest. Three organic acids activated NaHCO3-extractable organic P(P3) during the whole incubation period, and oxalic acid showed the strongest activating effect. Three organic acids enhanced the activation of NaOH-extractable inorganic P(P4) and oxalic acid displayed the strongest activating effect. Three organic acids inhibited the activation of NaOH-extractable organic P(P5). During the whole incubation period, three organic acids inhibited the activation of dilute HCl-extractable P(P6), dense HCl-extractable inorganic P(P7), dense HCl-extractable organic P(P8) and residual-P(P9).[Conclusion] Three organic acids showed different effects on soil P forms at different times of incubation. Oxalic acid showed the strongest activating effects, followed by malic acid and then citric acid.

    • Effects of agricultural wastes on greenhouse gas emission and global warming potential in black soil

      2017, 38(5):36-42. DOI: 10.7671/j.issn.1001-411X.2017.05.007

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      Abstract:[Objective] To study the effects of cow dung, chicken manure, and corn straw combined with chemical fertilizers on greenhouse gas emission and global warming potential.[Method] We used the static chamber technique and set up five treatments including control, chemical fertilizers only, cow dung plus chemical fertilizers containing 50% nitrogen of the total nitrogen in the treatment, chicken manure plus chemical fertilizers with 50% nitrogen, and straw plus chemical fertilizers with 90% nitrogen. Totally 240 kg·hm-2 nitrogen was applied in each treatment except for control.[Result] Among all treatments, the straw treatment resulted in the highest average emission flux and average total emission of CO2, being 388.96 mg·m-2·h-1 and 14 718.97 kg·hm-2 respectively. Nitrogen topdressing evidently promoted CO2 emission. The treatment of chemical fertilizers only resulted in the highest average absorption flux and average total absorption of CH4, being 0.042 mg·m-2·h-1 and 1.36 kg·hm-2 respectively, and resulted in the highest average emission flux and average total emission of N2 O, being 0.153 mg·m-2·h-1 and 5.75 kg·hm-2 respectively. The global warming potential in the straw treatment was significantly higher than those in other treatments. The global warming potential in the cow dung treatment was lower than that in the treatment of chemical fertilizers only, yet the difference was not significant.[Conclusion] Straw coverage can increase CO2 emission in black soil. Upland soil is an important sink of CH4 in the air. Compared with chemical fertilizers only, organic manure combined with inorganic fertilizer can reduce N2O releasing. The contributions of different agricultural wastes to atmospheric warming vary in degree.

    • Effects of intercropping on nitrogen component in latosolic red soil of slope land in young orchard

      2017, 38(5):43-49. DOI: 10.7671/j.issn.1001-411X.2017.05.008

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      Abstract:[Objective] To explore the effects of different intercropping patterns on nitrogen components of latosolic red soil of slope land in young orchard, and identify an optimal intercropping pattern that could improve soil nitrogen availability in orchard.[Method] A field experiment was carried out in Dimocarpus longan (Dl) orchard for two seasons (in autumn of 2015 and spring of 2016) to investigate the effects of four planting patterns[Dl monoculture (CK), Dl intercropping with Arachis hypogaea (Dl/Ah), Dl intercropping with Stylosanthes guianensis (Dl/Sg) and Dl intercropping with Lolium perenne (Dl/Lp)] on the contents of soil total nitrogen (TN), available nitrogen (AN), NO3-N, dissolved organic nitrogen (DON) and micrbial biomass nitrogen (MBN).[Result] Soil TN contents of Dl/Ah and Dl/Sg treatments and soil MBN contents of intercropping treatments were significantly higher than that of CK at the maturing stage of A. hypogaea in two seasons. At the pegging stage of A. hypogaea in two seasons, soil DON and AN contents of Dl/Ah treatment were significantly higher than that of CK. NO3-N contents of Dl/Ah and Dl/Sg treatments were significantly higher than that of CK, and enhanced by 64.4% and 34.2% respectively at the pegging stage of A. hypogaea in 2016. Soil TN, DON and NO3-N contents had a significantly positive correlation with plant nitrogen content, but were negatively correlated with the carbon content and carbon/nitrogen ratio of plant.[Conclusion] Dl/Ah and Dl/Sg treatments could significantly improve soil nitrogen component contents, and Dl/Ah treatment was better.

    • Research progress on the effect and mechanism of EGCG in the prevention and treatment of diabetes mellitus

      2017, 38(5):50-55. DOI: 10.7671/j.issn.1001-411X.2017.05.009

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      Abstract:表没食子儿茶素没食子酸酯(Epigallocatechin gallate,EGCG)是绿茶中的主要活性成分,具有抗癌、抑制肥胖、缓解代谢综合征等功效。本文总结EGCG预防和缓解糖尿病的相关研究,从降血糖功效、胰岛素抵抗、胰岛素分泌、糖尿病常见并发症等方面综合分析和阐述EGCG的作用机制,以期为绿茶缓解代谢综合征研究提供理论支持。

    • Selective bioactivity of enantiomers of three triazole fungicides against Fusarium spp.

      2017, 38(5):56-60. DOI: 10.7671/j.issn.1001-411X.2017.05.010

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      Abstract:[Objective] To study the activities of enantiomers of three triazole fungicides against Fusarium spp..[Method] Three chiral fungicides included tebuconazole, myclobutanil and difenoconazole. The activities of fungicide enantiomers against F. moniliforme, F. proliferatum and F. graminearum were assessed by mycelial growth rate method, respectively. The EC50 values of enantiomers were analyzed.[Result] SThe activities of different enantiomers against three kinds of Fusarium spp. were different. The activity of (–)-tebuconazole was higher than (+)-tebuconazole, and the EC50 difference of two enantiomers was 32–208 times. The inhibitory activity of (+)-myclobutanil was higher than (–)-myclobutanil, and the EC50 difference of two enantiomers was 1.4–6.4 times. (2R,4R)-difenoconazole showed the maximum activity among four enantiomers of difenoconazole, and the EC50 difference of four enantiomers was 3.7–15.5 times.[Conclusion] For Fusarium spp., the activities of three fungicides show selective difference. (–)-tebuconazole, (+)-myclobutanil and (2R,4R)-difenoconazole show higher activities. These results might contribute to screening higher active fungicides and reducing the use of pesticides.

    • Effects of Myrsine stolonifera extracts on growth and developmentof Plutella xylostella larvae

      2017, 38(5):61-66. DOI: 10.7671/j.issn.1001-411X.2017.05.011

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      Abstract:[Objective] To study the effects of Myrsine stolonifera extracts on growth and development of Plutella xylostella larvae.[Method] The bioactivities of M. stolonifera root, stem and leaf methanol extracts, and ethanol fractions of methanol extracts through macroporous resin against P. xylostella were determined by disc leaf method. The effects of ethanol fractions of extracts through macroporous resin on P. xylostella growth and development were studied.[Result] The root,stem and leaf methanol extracts of M. stolonifera and ethanol fractions of extracts through macroporous resin displayed stomach toxicity against P. xylostella. The 50% ethanol fraction of leaf extracts had the strongest insecticidal activity with an adjusted mortality of 75.56% after 72 h. The 95% ethanol fractions of root and stem extracts and 50% ethanol fractions of leaf extracts showed strong antifeedant activities and growth inhibition effects against P. xylostella larvae, with the antifeedant rates and growth inhibition rates over 90%. The extracts affected pupation and eclosion of P. xylostella.[Conclusion] M. stolonifera extracts display strong insecticidal activities against P. xylostella larvae. The insecticidal ingredients and mechanisms should be further studied.

    • GC×GC-TOF/MS analysis of the seed extract of Wisteria sinensis and the insecticidal activity

      2017, 38(5):67-73. DOI: 10.7671/j.issn.1001-411X.2017.05.012

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      Abstract:[Objective] To analyze the chemical composition, insecticidal and antioxidant activities of the seed extract of Wisteria sinensis, and provide a basis for developing botanical pesticide from W. sinensis germplasm resources.[Method] The seed extract of W. sinensis was analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOF/MS). The toxicity against Aphis gossypii was determined by topical application bioassay. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method.[Result] SA total of 61 components were identified from the seed extract of W. sinensis, mainly including esters, alkane, arene, etc. The constituents with higher than 9% relative content were p-xylene (14.33%), undecane (11.89%), 1,4-diethyl-benzene (11.02%) and decane (9.54%). The seed extract of W. sinensis showed insecticidal activity against A. gossypii with the LC50 value of 193.22 mg·L–1 after 24 h treatment, and also showed antioxidant activity with the IC50 value of 4.15 g·L–1 against DPPH.[Conclusion] The seed extract of W. sinensis has strong insecticidal activity, and has the potential to be developed into a natural insecticide for controlling A. gossypii.

    • Genetic analysis model of forest based on space and competition effects

      2017, 38(5):74-80. DOI: 10.7671/j.issn.1001-411X.2017.05.013

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      Abstract:[Objective] To improve the accuracy in genetic analysis of forest establishing an analysis model based on space and competition effects.[Method] The data was simulated by R software and its package breedR. The additive effect and neighbor competition effect were fitted using XFA1 structure and the spatial effect was fitted using AR1 structure for both simulated and measured data. Four models (randomized block design model, RCBM; spatial model, SM; spatial with measured error model, SUM; spatial and competition model, SCM) were established and analyzed using ASReml to estimate genetic parameters for comparison.[Result] SThe estimated results showed that SCM was the best model for the simulation data. SCM greatly reduced the random error variance from 7.56 (RCBM) and 5.72 (SUM) to 3.13 (SCM), decreased by 58.6% and 45.3%, respectively. SCM could estimate the genetic variance of competition from surrounding neighbors. The individual heritability assessed by SCM was around 0.40, higher than those of RCBM (0.24) and SUM (0.30). SCM obtained stable estimated results under different settings of initial values for parameters. Furthermore, for the measured data, the estimated results were consistent with the simulation data.[Conclusion] SCM is a new individual-tree mixed model and could be used for genetic analysis of forest.

    • Genetic variation analysis of growth and form traits of Castanopsis hystrix in the second generation seed orchard

      2017, 38(5):81-85. DOI: 10.7671/j.issn.1001-411X.2017.05.014

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      Abstract:[Objective] To evaluate and utilize the resources in the second generation seed orchard of Castanopsis hystrix, and develop elite genotypes with genetic merit.[Method] We investigated the growth and form traits of 56C. hystrix clones in the second generation seed orchard at Longyandong forest farm, Guangdong Province. The variation coefficients and correlations of different traits were analyzed. Principal component analysis and cluster analysis were performed.[Result] The variation coefficients of ten growth and form traits of 56 C. hystrix clones ranged from 11% to 47%, and the average was 28.2%. Height and diameter at breast height, crown width and height, crown width and diameter at breast height, diameter at breast height and branch number, branch size and leaf density all had significant positive correlations(P<0.01). Crown width and branch angle, taper degree and branch size had significant negative correlations(P<0.05). Principal component analysis indicated that ten traits could be explained by the first three principal components, accounting for 85% of cumulative proportion of variations. Based on hierarchical cluster analysis, 56 clones were divided into four groups.[Conclusion] Growth and form traits among C. hystrix clones had extensive variation with rich genetic diversity. Different degrees of correlations are found among traits. This study provides a basis for parent selection in breeding intraspecific hybrid of C. hystrix.

    • Effects of plant growth regulators on vegetative and reproductive growth of Dalbergia odorifera

      2017, 38(5):86-90. DOI: 10.7671/j.issn.1001-411X.2017.05.015

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      Abstract:[Objective] To investigate the effects of plant growth regulators on vegetative and reproductive growth of Dalbergia odorifera, and provide useful suggestions for plantation management of D. odorifera with different purposes.[Method] We set up a randomized block experiment using 10-year-old D. odorifera. Leaves were sprayed with three different concentrations of gibberellin (GA3), paclobutrazol (PP333) or benzyladenine (6-BA). Changes in morphology, growth and dry weight of 1-year-old branch, flower and leaf at full-bloom stage were measured. The changing patterns of vegetative and reproductive growth after treating with plant growth regulators were investigated using statistical analysis software.[Result] Both type and concentration of plant growth regulators caused significant differences in vegetative and reproductive growth of D. odorifera (P<0.05). Foliar application of 200, 100 mg·L–1 GA3 or 500 mg·L–1 6-BA significantly promoted vegetative growth of D. odorifera, while inhibited reproductive growth. Application of 200 mg·L–1 GA3 had the best inhibition effect on reproductive growth with the ratio of vegetative branch increased by 140.84% and inflorescence number reduced by 79.41% compared to control (P<0.05). Application of 100 mg·L–1 GA3 had the best promoting effect on vegetative growth with the vegetative branch length and diameter, compound leaf number and dry weight of simple leaf increased by 218.08%, 120.70%, 132.38% and 217.33% compared to control (P<0.05). On the other hand, foliar application of 1 500, 2 000 mg·L–1 PP333 and 50 mg·L–1 6-BA significantly promoted the reproductive growth of D. odorifera. Application of 2 000 mg·L–1 PP333 had the best promoting effect on reproductive growth with the ratio of reproductive branch, the number and diameter of inflorescence increased by 73.50%, 50.37% and 31.30% respectively compared to control (P<0.05).[Conclusion] For plantation management of D. odorifera, foliar application of 200 mg·L–1 or 100 mg·L–1 GA3 can inhibit reproductive growth and promote vegetative growth, and should be used for large timber production. Foliar application of 2 000 mg·L–1 PP333 can promote reproductive growth, and should be suitable for selective breeding.

    • Investigation of browning factors in embryogenic callus culture of Pinus tabulaeformis and optimization of proliferation medium

      2017, 38(5):91-96. DOI: 10.7671/j.issn.1001-411X.2017.05.016

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      Abstract:[Objective] To study the effects of different factors on browning of embryogenic callus of Pinus tabulaeformis during proliferation, and optimize the culture medium based on proliferation rate for lower browning rate and higher efficiency.[Method] Embryogenic callus of P. tabulaeformis from nine cell lines and three different year were used as material.We performed a serious of single factor experiments and calculated the browning rates and proliferation rates of embryogenic callus under the treatments of different callus number, pH, phytagel content, type and content of sugars, and culturing time. Orthogonal experiment was then conducted to screen out the best culture conditions.[Result] of the single factor experiments showed that browning rate was significantly different among different genotypes, and it was significantly positively correlated with the age of subculture. The browning rate was relatively low and the proliferation rate was relatively high when the callus number in each petri dish was 6–7, medium pH was 5.8–6.0, phytagel was 2.0–3.0 g·L–1, and sucrose was 10 g·L–1. Sucrose was better than glucose and maltose.[Conclusion] Based on the orthogonal design, placing 7 callus in each 90 mm petri dish, adding 2.5 g·L–1 phytagel and 10 g·L–1 sucrose to the medium, and adjusting the pH to 5.9 could achieve the preferred browning rate,proliferation rate and efficiency.

    • Effects of spraying parameters of small plant protection UAV on droplets deposition distribution in citrus canopy

      2017, 38(5):97-102. DOI: 10.7671/j.issn.1001-411X.2017.05.017

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      Abstract:[Objective] To explore droplet deposition distribution patterns from aerial spraying and the application prospect of small plant protection unmanned aerial vehicle (UAV) for fruit trees, and study the influence of spraying parameters of UAV on droplets deposition distribution in citrus canopy.

      Method

      Spray test with six-rotor plant protection UAV was arranged by an orthogonal test of three factors (flight height, flight velocity, nozzle flow rate).[Result] SPreferred spraying operation parameters for small plant protection UAV were 2.5 m flight height, 4.0 m·s–1 flight speed and 1.0 L·min–1 nozzle flow rate based on the test results of density and uniformity of deposited droplets. The factors that affected the density of deposited droplets were in order of flight velocity, flight height, and nozzle flow rate. Test No.2 with 2.0 flight height, 4 m·s–1 flight speed, 0.6 L·min–1 nozzle flow rate and No.8 with 2.0 m flight height, 1 m·s–1 flight speed, 1.0 L·min–1 nozzle flow rate resulted in relatively high density and penetrability of deposited droplets, and the penetrability of droplets were 22.21% and 22.41% respectively. The factors that affected the penetrability of deposited droplets were in order of flight height, flight velocity, and nozzle flow rate.[Conclusion] Due to the influence of the wind field of UAV rotor and the unique structure of citrus, the operating parameters of plant protection UAV should be optimized to ensure effective deposition and distrubition of droplets in citrus canopy from aerial spraying. This research can provide reference and guidance for reasonable spraying using small UAV on fruit trees, for improving the spraying efficiency.

    • Multi-objective optimization design for turntable of dead pig vehicle based on sensitivity analysis

      2017, 38(5):103-109. DOI: 10.7671/j.issn.1001-411X.2017.05.018

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      Abstract:[Objective] To improve the working performance of dead pig vehicle and cut down the costs, multi-objective optimization design was carried out on the structure of turntable.[Method] By using the Creo Simulate three-dimension design software, the statics finite element analysis and sensitivity analysis of the original turntable were executed.Based on the above analysis, a multi-objective optimization design model for the structure of turntable was built.The optimal design scheme was selected using the fuzzy matter-element analysis method and weighted average method.[Result] The multi-objective optimization design model for the structure of turntable was built, and six groups of non-inferior solution were obtained. The optimal design scheme was obtained by evaluating and preferring. Comparative analysis on parameters before and after optimization showed that the turntable mass after optimization was 20.90 kg and reduced 19.43%. The maximum equivalent stress was 1.44 MPa and reduced 4.00%.[Conclusion] The proposed structural optimization design for the turntable of dead pig vehicle based on sensitivity analysis is reasonable and feasible. The result can provide the theoretical guide for improving turntable structure.

    • Application of genetic algorithm based on group and elite strategy for robot navigation

      2017, 38(5):110-116. DOI: 10.7671/j.issn.1001-411X.2017.05.019

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      Abstract:[Objective] To solve the problems that picking robot could not find the multipath quickly and accurately in planning route in complex plantation environment, a genetic algorithm based on group and elite strategy (GGABE) was proposed.[Method] Firstly, an initial population was generated and was divided into several groups using the Sigmoid function. After n times of operations of selections, crossovers and mutations in each group separately, k optimal paths with equal length were then acquired in each group. Comparing the optimal paths among different groups, the shortest paths were chosen as the final optimal paths. With all population parameters being the same, three types of algorithms, including simple genetic algorithm(SGA), ungrouped elite genetic algorithm (EGA) and GGABE, were tested 50 times respectively on 15×15 and 25×25 maps. The prototype verification experiments were carried out in the plantation.[Result] Eight shortest paths with the average length of 20.970 6 were found in map 1 by GGABE. Only one shortest path was found in map 1 with the other two algorithms. Eight shortest paths with the average length of 38.041 6 were found in map 2 by GGABE. Three optimal paths were found in each of the 50 verification experiments, and the average consumption time for route planning was 15.543 319 s.[Conclusion] GGABE has fast convergence speed and can quickly and accurately find out all optimal paths, which are able to traverse the entire plantation, from the map.

    • Design and simulation of hydraulic driven disc harrow

      2017, 38(5):117-124. DOI: 10.7671/j.issn.1001-411X.2017.05.020

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      Abstract:[Objective] To design a hydraulic driven disc harrow, and to use it under the working conditions of the middle-lower Yangtze plain with sticky and sealing soil, large amount of rice straws and fluctuating soil moisture content.[Method] The structure and operation parameters of the disc harrow were analyzed and the hydraulic driven system was designed. The rotary speed ranges of the hydraulic motor were determined according to the forward speed of the system. The motion trajectory of the notched disc was analyzed and the critical angle of the disc was determined. The process that the disc cutting the soil was analyzed using the finite element simulation method based on ANSYS/LS-DYNA.[Result] The rotary speed of hydraulic motor ranged from 60 to 168 r·min–1. The critical angle of the disc was 23°. The simulation results showed that the resistance of soil cutting by the disc changed periodically, increased gradually as soil depth increased and then became stable. Compared with a negative disc, the hydraulic driven notched disc could rotate more soil and its tillage depth was more stable. Field experiment showed that the tillage depth for the hydraulic driven notched disc was 85–120 mm and the coefficient of variation for stability in tillage depth was 9.6%.[Conclusion] The hydraulic driven disc harrow meets the design requirements.