XU Hanhong , LAI Duo , ZHANG Zhixiang
2017, 38(4):1-11. DOI: 10.7671/j.issn.1001-411X.2017.04.001
Abstract:Azadirachtin is primarily known as an effective botanical insecticide, it has been widely used in field practice for more than 30 years, and plays an important role in the global crop protection and ecological security. In this review, we traced the discovered history of azadirachtin and the situation of neem introduction, and summarized the molecular mechanism inducing autophagic apoptosis, the latest progresses of molecular mechanism and biosynthesis of azadirachtin, as well as molecular biology. The neem tree, Azadirachta indica A. Juss, was first introduced by Shin-Foon Chiu’s group into China in 1983, and then Chinese scholars made great efforts to introduce and breed neem tree, planted more than sixty thousand hectares of neem trees, which provided material guarantee for the large-scale production of azadirachtin pesticide in China. The commercial application of azadirachtin was authorized by China’s Ministry of Agriculture(CMA) as a new insecticide in 1997. Azadirachtin had become the main low toxicity and low residue pesticide recommended by CMA in 2014, and resulted in good social and ecological benefits. Chinese scholars discovered that azadirachtin could induce autophagy in insect cell, and illuminated the molecular regulation mechanism of apoptosis and autophagy induced by azadirachtin. As strengthening the source control of quality and safety for agricultural product, the research and application of azadirachtin will be more and more widespread. The basic research should be intensified for future work to find out the molecular target of azadirachtin, which will provide a theoretical basis for scientifical application of azadirachtin.
YAN Ying , GU Huaiyu , XU Hanhong , ZHANG Zhixiang
2017, 38(4):12-18. DOI: 10.7671/j.issn.1001-411X.2017.04.002
Abstract:【Objective】To investigate the inductive effects of azadirachtin on taste memory in Drosophila melanogaster (fruit fly) and the regulation of dopamine signaling in such memory formation. 【Method】Aversive taste memory induced by azadirachtin was tested by proboscis extension reflex (PER). Effects of azadirachtin on membrane excitability and receptor currents of dopaminergic neurons in D. melanogaster brain were studied using pressure injection combined with whole-cell patch clamp recording. 【Result】Both azadirachtin A and the azadirachtin dry powder could significantly inhibit the probability of PER,which were 60.34% and 17.24% respectively(P<0.007). The effect of dry powder was more obvious. Different clusters of dopaminergic neurons responded variously to azadirachtin. PPL1, PAM and PPM2 subgroups showed increasing trends in excitability, in which the changes of PPL1 cluster neurons were most pronounced. Azadirachtin showed agonistic effect on D1 receptor, and such effect could be inhibited by D1 receptor specific antagonists.【Conclusion】Azadirachtin can induce aversive taste memory in Drosophila, and such memory is regulated by dopaminergic signals in the brain.
SHAO Xuehua , LAI Duo , MAO Genlin , XU Hanhong
2017, 38(4):19-24. DOI: 10.7671/j.issn.1001-411X.2017.04.003
Abstract:【Objective】To investigate the effect and mechanism of azadirachtin on proliferation and apoptosis in Plutella xyllostella embryonic cells. 【Method】P. xyllostella embryonic cells were divided into azadirachtin treated and untreated groups, the inhibition rate of cells proliferation was detected using CCK-8 kit. The cell death and apoptotic body were observed using laser confocal microscope after stained by PI and DAPI respectively. The expression of Caspase-3 and the phosphorylation of pathway protein Akt were detected using Western-blotting.【Result】Azadirachtin had significant inhibitory effect on the proliferation of P. xyllostella embryonic cells, and the effect was dose-dependent. IC50was 4.4 μg·mL-1 in 24 h. Dead cells could be observed in azadirachtin treated group after stained by PI, and apoptotic body could be found in the same group after stained by DAPI. Caspase-3 protein was cleaved and Akt phosphorylation was inhibited.【Conclusion】 Azadirachtin has significant inhibitory effect on the proliferation of P. xyllostella embryonic cells. By inhibiting the activation of Akt signaling pathway, azadirachtin can induce cells to produce Caspase-3-dependent type I apoptosis.
ZHANG Ling , WANG Dehua , MA Yi , XU Hanhong
2017, 38(4):25-29. DOI: 10.7671/j.issn.1001-411X.2017.04.004
Abstract:【Objective】 To investigate the effects of azadirachtin on cell proliferation,glucose uptake and insulin secretion in min6 cells and their possible mechanisms. 【Method】 The min6 cells were cultured in vitro and treated with various concentrations of azadirachtin for 48 h.Cell proliferation was measured. In the presence of 5.5 and 25.0 mmol·L-1 glucose,glucose uptake was measured and insulin secretion in min6 cells were detected by the insulin ELISA kit. 【Result】 Azadirachtin promoted the proliferation of min6 cells in the presence of 5.5 and 25.0 mmol·L-1 glucose compared to the control group. Compared with the 25.0 mmol·L-1 glucose condition,azadirachtin in the presence of 5.5 mmol·L-1 glucose more significantly promoted glucose uptake and insulin secretion in min6 cells. 【Conclusion】Azadirachtin could affect insulin secretion by regulating glucose concentration.
LAI Duo , KANG Xianghui , SHAO Xuehua , KUANG Shizi , TIAN Shiyao , XU Hanhong
2017, 38(4):30-36. DOI: 10.7671/j.issn.1001-411X.2017.04.005
Abstract:【Objective】 To manufacture neem bioorganic fertilizer using neem cake waste, and test its effects on banana growth and fusarium wilt caused by Fusarium oxysporum f. sp. cubense.【Method】 Neem bioorganic fertilizer was prepared by fermenting neem cake with a biocontrol bacteria Bacillus amyloliquefaciens HN-11. The effects of neem bioorganic fertilizer on banana growth and fusarium wilt were determinated by inhibition test and pot experiment. The pathogen mycelial morphology was observed by using a scanning electron microscope (SEM). 【Result】B.amyloliquefaciens HN-11 had obvious inhibitory activity against F. oxysporum Foc4 with an inhibition rate of 72.1%. Biocontrol strain HN-11 had good compatibility with neem cake. Treated with 5% and 10% neem bioorganic fertilizer, the banana grew better than the control group with the fresh weight, dry mass, plant height and stem diameter significantly increasing. The disease indexes of the two treatment groups were 20 and 25, and the control efficiencies against fusarium wilt disease reached 72.2% and 77.8%, respectively. Strain HN-11 reduced the number of Foc4 spores in soil and destroyed their mycelial structure. 【Conclusion】Application of mature neem cake by fermenting with Bacillus amyloliquefaciens HN-11 could avoid phytotoxicity to banana plants. The prepared neem bioorganic fertilizer can efficiently promote banana growth and prevent fusarium wilt disease.
YANG Xiaoyun , HUANG Qiliang , JIANG Tenghui , XU Hanhong
2017, 38(4):37-40. DOI: 10.7671/j.issn.1001-411X.2017.04.006
Abstract:【Objective】To identify the residual and degradation dynamics of azadirachtin in cabbage and soil after spraying 0.3%azadirachtin emulsifiable concentrate during the growth period of cabbage (Brassica oleracea).【Method】Azadirachtin was added with three concentrations of 0.1,0.5 and 1.0 mg·kg-1 within the range from 0.05 to 5.00 mg·kg-1. Azadirachtin was extracted from cabbage and soil using acetonitrile assisted with ultrasonic, purificated using a florisil solid phase extraction column, detected by HPLC and quantified by external standard method.【Result】The average recovery rates of azadirachtin in cabbage ranged from 88.52% to 93.21% with relative standard deviations ranging from 2.75% to 3.55%, and the average recovery rates in soil were ranged from 90.69% to 93.32% with relative standard deviations ranging from 2.09% to 3.46%.The halflives of azadirachtin in cabbage and soil were 0.89 and 2.40 d respectively.【Conclusion】Azadirachtin is an easily degradable pesticide. Application of 0.3% azadirachtine mulsifiable concentrate is safe and recommended.
YANG Xiaoyun , JIANG Tenghui , HUANG Qiliang , XU Hanhong
2017, 38(4):41-47. DOI: 10.7671/j.issn.1001-411X.2017.04.007
Abstract:【Objective】 To study hydrolysis of azadirachtin in water systematically.【Method】Azadirachtin A from the 44.56% azadirachtin TC was isolated and purified by silica column chromatography and semi-preparative high performance liquid chromatography (HPLC). The chemical structure and content of isolated azadirachtin A were identified by nulear magnetic resonance (NMR) and HPLC. A method for determining azaditachtin residue in water by HPLC was established. 【Result】The mass fractions of azadirachtin A were 90.37% and 91.82% detected by NMR and HPLC respectively. When azadirachtin was added with the concentrations of 0.1, 1.0 and 5.0 mg·kg-1, the average recovery rates of azadirachtin from water samples ranged from 92.53% to 94.12%, the variation coefficients ranged from 0.35% to 0.84%, and the minimum detection limit was 0.012 mg·L-1. Azadirachtin was stable in buffer solutions with pH varying from 4.0 to 6.0. When pH was above 8.0, hydrolysis of azadirachtin was accelerated, and the degradation half-life was 14.856 h at pH 8.0 and declined to 0.033 h at pH 10.0. The degration half-lives of azadirachtin in buffer solutions at pH 6.0 were 24.68, 13.69 and 2.36 d under 25, 35 and 45 ℃ temperature respectively, while were 9.35, 6.51 and 0.94 d at pH 7.0. A lactone derivative of azadirachtin was obtained by isolating and purifing hydrolysate in buffer solution at pH 2.0. 【Conclusion】Azadirachtin is extremely unstable in alkaline environment while relatively stable in weak acid environment. Temperature has a great effect on the degradation of azadirachtin and the degradation accelerates as temperature increases.
LI Yiming , CHEN Xiaotian , WANG Yongqing , CHENG Dongmei , ZHANG Zhixiang
2017, 38(4):48-51. DOI: 10.7671/j.issn.1001-411X.2017.04.008
Abstract:【Objective】 To study the biological activity of azadirachtin-rich dry powder, azadirachtin A and azadirachtin B, and establish a method for determinating azadirachtin content of dry powder.【Method】 Azadirachtin-rich dry powder was prepared by ethyl acetate extraction method, the azadirachtin content of dry powder was determined by HPLC and the biological activity was measured by leaf disc test. 【Result】AFC50 of zadirachtin-rich dry powder was 0.28 μg·mL-1 against 2nd instar larvae of Spodoptera litura and 70.71 μg·mL-1 against the 3rd instar larvae of Pieris brassicae 24 h after treatment. The antifeedant activity of azadirachtin-rich dry powder was clearly higher than that of azadirachtin A and azadirachtin B. 【Conclusion】 This preparation method of the dry powder is simple, effective, and has good biological activity. It is recommended for popularization and application.
CHEN Ziyu , JIANG Dongmei , KANG Bo , GUAN Cheng , LONG Shiyun , YI Zhixin , XU Qilin
2017, 38(4):52-56. DOI: 10.7671/j.issn.1001-411X.2017.04.009
Abstract:【Objective】 To observe the effects of intraperitoneal injection of spermidine on polyamine metabolism in mouse ovary.【Method】 Mice were injected with different doses of spermidine[0(control), 0.05, 0.10 and 0.15 mg·g-1]. Realtime fluorescent quantitative PCR was used to determine the ovarian expression levels of key genes in polyamine metabolism. High performance liquid chromatography (HPLC) was used to detect the polyamine levels in mouse ovarian tissues.【Result】 After administration of 0.15 mg·g-1 spermidine, the expression of ODC, OAZ1, SPMS, SSAT, PAOX and SMOX genes in ovarian tissues were significantly higher compared to other three groups. SPDS gene expressions of all three spermidine administration groups were significantly lower compared to control. After administration of 0.10 mg·g-1 spermidine, the putrescine and spermidine contents in mouse ovary were significantly higher compared to control, while spermidine administration had no significant effect on spermine content in ovary. 【Conclusion】 Exogenous spermidine injected intraperitoneally can change polyamine content and polyamine metabolism-related gene expression in mouse ovary. Such effects are dose-dependent. Exogenous spermidine can potentially participate in the regulation of ovarian function through adjusting polyamine metabolism.
SUN Yuan , ZENG Yao , YAN Baozuo , LI Haiyun
2017, 38(4):57-61. DOI: 10.7671/j.issn.1001-411X.2017.04.010
Abstract:【Objective】To illustrate the ultrastructure of the spermatozoon of Raillietina cesticllus. 【Method】Transmission electron microscope was used to observe the morphorlogy and structure of the spermatozoon of R. cesticllus parasitized in chicken intestine.【Result】The spermatozoon of R. cesticllus is filiform, tapers at both ends, has crested-like body and lacks the mitochondria. It has axonemes with the “9+1” pattern. Based on longitudinal sections of R. cesticllus spermatozoon, five regions could be distinguished. RegionⅠcorresponds to the anterior extremity of the spermatozoon, having a crested-like body. RegionⅡ is characterized by the presence of cortical microtubules, a periaxonemal sheath andintracytoplasmic walls. Region Ⅲ has plenty of electro-dense granules. Region Ⅳ is characterized by the presence of the nucleus. RegionⅤcorresponds to the posterior end of the spermatozoon, having free flagellums. The spermatozoons of R. cesticllus and R. echinobothrida each has one crested-like body, while the spermatozoons of all other six reported davaineid cestode each has two crested-like bodies. The rotation angle of the crested-like body of R. cesticllus is 40°to 55°, other than 35° for R. echinobothrida. 【Concluison】The number and rotation angle of the crested-like body of the spermatozoon head can discriminate R. cesticllus from other seven reported Davaineidae cestode.
XIANG Zhenggang , GENG Yi , ZHANG Yuwei , YANG Zexiao , OUYANG Ping , LI Yajun , MOU Weihao , WANG Shizhen
2017, 38(4):62-68. DOI: 10.7671/j.issn.1001-411X.2017.04.011
Abstract:【Objective】To understand genotyping characteristics, genetic variation and the distribution of virulence factors of Staphylococcus aureus isolated from rabbits in Sichuan area. 【Method】Forty-one S.aureus strains were isolated from rabbits in Sichuan area. The strains were identified for femB gene specifity. Methicillin-resistant S.aureus (MRSA) were screened out. Thirteen common virulence genes were detected using PCR. Genotyping characteristics were studied by using multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE). 【Result】There were 31 MRSA strains out of 41 S.aureus strains, and the detection rate was 75.61%. Totally nine virulence genes were detected, nuc, hla,eta and clfA genes existed in all strains, and the positive detection rates of sea, sec, see, hlb and PVL genes were 9.7%, 85.4%, 80.5%, 90.2% and 7.3%, respectively. MLST results showed that 41 S.aureus strains belonged to two sequence types (ST398, ST3320) and one clonal complex CC398. ST398 was the preponderant sequence type, and the proportion was 97.6%. PFGE analysis divided 41 S.aureus strains into 18 banding types, whereas strains from different regions had low variation in banding patterns.【Conclusion】S.aureus strains isolated from rabbits in Sichuan area have high carrying rates of virulence factors, and therefore are potential security risk to rabbit farming industry. The genotyping analysis indicates that the prevalent strains of S.aureus isolated from parts of Sichuan Province have low genetic variation, and there are close genetic relationships among different strains.
WU Xiaofeng , XIAO Jinbang , SHEN Liuhong , JIANG Sixun , QIAN Bolin , DENG Junliang , FU Hongqing , ZUO Zhicai , CAO Suizhong , YU Shumin , JIANG Tao
2017, 38(4):69-75. DOI: 10.7671/j.issn.1001-411X.2017.04.012
Abstract:【Objective】To explore the impact of Chinese herbal formula “Huirukang” on serum estrogen(E), progesterone(P4) and transforming growth factor β1(TGF-β1) levels in dairy cows during the milk withdrawal period.【Method】Eighty healthy cows in late pregnancy with (15.42±0.71) kg daily milk yield were randomly divided into four groups: control group and Chinese medicine groups(fed 400, 500 and 600 g “Huirukang” daily). The method of gradual milk cessation was used. We collected venous blood from the cow tail on day 0, 1, 3, 5, 7, 9 and 11, and recorded the daily milk yield. ELISA was used to determine the expression levels of serum E, P4 and TGF-β1.【Result】Control group and Chinese medicine groups (400, 500, 600 g) dried off on day 11, 7, 5 and 5 respectively. Serum E levels declined in all four groups, and the decline in control group was slower compared to Chinese medicine groups. P4 level did not change significantly during the milk withdrawal period for control group. P4 levels increased first in Chinese medicine groups, then declined after the milk withdrawal period, and by the end of the test period were still significantly higher compared to control group. TGF-β1 levels increased in all four groups during the milk withdrawal period, and declined after the milk withdrawal period in Chinese medicine groups. The levels of E, TGF-β1 and daily milk yield showed significant correlation between each other during the milk withdrawal period, while P4 had no significant correlation with E, TGF-β1 or daily milk yield.【Conclusion】During the milk withdrawal period, Chinese herbal formula “Huirukang” can significantly promote cows to dry off. E is a negative regulation factor for milk withdrawal, while TGF-β1 is a positive regulation factor. P4 has no significant effect on milk withdrawal.
LUO Liulong , MA Chunquan , LIANG Zisen
2017, 38(4):76-79. DOI: 10.7671/j.issn.1001-411X.2017.04.013
Abstract:【Objective】 To study the injury to immune organs of piglets from three kinds of PRRS vaccine(MLV, TJM 92 and JXA-1R vaccines).【Method】Fifty new-born healthy piglets were devided into four groups:non-immunized control group(CK group), MLV vaccine group(A group), TJM 92 vaccine group (B group), JXA-1R vaccine group (C group). Every piglit in the experimental group were vaccinated. Then paraffin sections were prepared after pathological anatomy. Changes in percentages of esterase-positive T cells and plasma cells (effector B cells) of different immune organs were summarized by using optimized esterase (α-NAE) and methyl green-pyronin (MG-P) staining. 【Result】There were significant or highly significant differences in the percentages of esterase-positive T cells and plasma cells of immune organs between each immunized group and CK group. 【Conclusion】Three kinds of vaccine all have injuries to immune organs of piglets. Injury from JXA-1R vaccine is the strongest, followed by TJM92 vaccine and then MLV vaccine.
SONG Shiming , CHEN Zhaojie , WEI Jie , DENG Cheng , TAN Huihua , LI Xuesheng
2017, 38(4):80-86. DOI: 10.7671/j.issn.1001-411X.2017.04.014
Abstract:【Objective】To study the residues and dissipation dynamics of tricyclazole and azoxystrobin in rice plant, soil and paddy water.【Method】Rice samples were extracted with acetonitrile or dichloromethane, the extracts were enriched and then analyzed by high performance liquid chromatography(tricyclazole) and gas chromatography(azoxystrobin).【Result】The limits of quantification(LOQ) were 0.05 and 0.01 mg·L-1, the average recovery rates ranged from 78.5% to 100.8% and 73.9% to 109.7%, and the relative standard deviations (RSD) ranged from 1.0% to 12.9% and 3.1% to 12.9% for tricyclazole and azoxystrobin respectively. The dissipation dynamics of tricyclazole and azoxystrobin residues in rice plant, soil and paddy water fitted the first-order kinetic equations. The dissipation half-lives of tricyclazole and azoxystrobin in rice ranged from 2.4 to 13.1 and 4.3 to 16.1 d respectively. 【Conclusion】Tricyclazole and azoxystrobin are both easily degradable pesticides. The sensitivity, accuracy and precision of the detection methods all meet the requirements for pesticide residue analysis.
XU Xiuyu , ZHANG Weiqiang , HUANG Yuhui , GAN Xianhua , ZHONG Chonglu , ZHANG Huaxin
2017, 38(4):87-94. DOI: 10.7671/j.issn.1001-411X.2017.04.015
Abstract:【Objective】 To select convenient, accurate and reliable identification methods of bacterial wilt resistance in Casuarinaceae, identify and evaluate the bacterial wilt resistance of Casuarinaceae germplasm resources in China, and screen out highly resistant clones.【Method】Based on the screening techniques of Casuarinaceae resistant lines as well as the identification methods of bacterial wilt in other plants, such as Lycopersicon esculentum, Nicotiana and Eucalyptus, we designed eight different approaches to inoculate Ralstonia solanacearum into Casuarinaceae. The effects of using hydroponic rooting seedling, twig, lignified green branch, lignified brown branch, bacterial wilt crude toxin, and root with or without injure of potted seedlings in inoculation on bacterial wilt resistance identification were studied. 【Result】After injured root inoculation of potted seedling,the mortalities of different Casuarinaceae clones ranged from 25.79% to 83.06% with significant differences among A14, K18 and G1, 30 clones(P<0.05). After hydroponic inoculation of lignified brown branch,the disease indexes of different clones ranged from 2.16 to 69.48 with significant differences among A14, K18 and G1, 30 clones(P<0.05). These two inoculation approaches enabled effective discrimination between resistant and infected clones, and had highly significant positive correlation (r=0.856 5). Non-injured root inoculation of potted seedling, hydroponic inoculation of rooting seedling and tender branch did not result in significantly differences in disease resistance among clones(P>0.05), and they couldn’t help with effective identification of bacterial wilt resistance in Casuarinaceae. Inoculation of lignified green branch only resulted in small differences among clones, and therefore it led to difficulties in classification and could easily cause detection error. The concentration of bacterial wilt crude toxin was hard to control during inoculation. Using hydroponic inoculation of lignified brown branch, 53 Casuarinaceae clones were evaluated and 12 highly resistant clones such as X1, 30, hybrid and G1 clones were screened out. 【Conclusion】 Injured root inoculation of potted seedling and hydroponic inoculation of lignified brown branch are both preferred inoculation approaches for identifying bacterial wilt resistance of Casuarinaceae. The rest inoculation approaches tested in this study were not suitable for identification of bacterial wilt resistance in Casuarinaceae.
YAO Xiaolan , HAO Jianfeng , WU Xuanbei , YAO Junyu , SUN Qianhui , WU Xia
2017, 38(4):95-102. DOI: 10.7671/j.issn.1001-411X.2017.04.016
Abstract:【Objective】 In order to provide a scientific basis for sustainable management of Betula luminifera plantation, we studied the effects of different stand densities on community structure and species diversity of 20-year-old B. luminifera plantation in Baiyunshan, north Sichuan. 【Method】Using the typical sampling method, the community structure and species diversity of B. luminifera plantation under low density (1 050-1 150 trees·hm-2), medium density (1 450-1 550 trees·hm-2) and high density (2 150-2 250 trees·hm-2) in Baiyunshan were studied. 【Result】 In total, 110 species belonging to 52 families and 91 genera were recorded. There were 59, 42 and 57 species under high, medium and low densities respectively. In terms of community structure, most species in communities of medium and high densities were of medium diameters [5,11) cm, while most species in communities of low density were of large diameters [11,17) cm. Communities of three different densities were composed of species with similar heights, mostly ranged from medium to high height [9,13) m. The species richness indexes (D), Shannon-wienner indexes (H) and Simpson indexes (H′) were all in the order of tree layer<shrub layer<herb layer. In the tree layer, different species diversity indexes were in the order of medium density>low density>high density, while in the shrub and herb layers, the indexes of D and H were in the order of low density>medium density>high density. 【Conclusion】Medium density is most conducive to the maintenance of species diversity and the natural regeneration of B. luminifera plantation in Baiyunshan, north Sichuan.
CHEN Shengde , LAN Yubin , LI Jiyu , ZHOU Zhiyan , LIU Aimin , XU Xiaojie
2017, 38(4):103-109. DOI: 10.7671/j.issn.1001-411X.2017.04.017
Abstract:【Objective】 To find out the deposition and distribution patterns of droplets sprayed by small unmanned helicopters in rice field, and compare the differences between agricultural UAV and artificial spray. 【Method】 Spraying tests were performed to compare the influence of two leading UAVs in the market(oil-driven small single rotor UAV and electric-driven small single rotor UAV) . The effects of different operating parameters on droplet deposition and distribution in rice canopy were studied. The spraying outcomes and efficiencies of aerial and artificial spray methods were compared. 【Result】The operating parameters of aerial spray had the same influential trend on both droplets deposition amount and penetrability. Slower operating speed led to more depositing droplets in plants and higher penetrability. Lower operating height led to more depositing droplets but lower penetrability. For oil-driven small single rotor UAV, operating height had an obvious effect on the depositing uniformity of droplets, and for electric driven small single rotor UAV, operating speed had an obvious effect on the depositing uniformity of droplets because of different wind field strengths of rotors in different types of UAV. Artificial spray resulted in the worst depositing uniformity of droplets in upper, middle and lower rice plants and the lowest penetrability(110.42%) of droplets in rice plants. The droplets for artificial spray mainly deposited on upper plants and only 3.27% medicinal liquid reached the bottom of plants, while 10%-30% reached the bottom for aerial spray.【Conclusion】From the perspectives of spraying outcomes and efficiencies, aerial spray has better depositing effect and ten times higher efficiency compared to artificial spray. Aerial spray costs low and brings high benefit.
ZOU Yi , HAO Xiangze , HE Ruiyin
2017, 38(4):110-116. DOI: 10.7671/j.issn.1001-411X.2017.04.018
Abstract:【Objective】 To solve the problems of slow speed and inefficiency in mechanical seeding of rice.【Method】Rice was directly seeded using the air distribution seed-metering device. An α-R air distribution seed-metering device was designed and optimized. It consisted a bell type lumen with adjustable R and a shunt seal cap with adjustable α. Numerical simulations of air distribution and metering process were performed by using EDEM-Fluent coupling module, and the bench test on seeding performance was carried out. 【Result】The simulation results showed that the highest velocity of rice particles in the combined α-R distributor was 5.416 m·s-1. The area of vortex stagnation was smaller than that of the traditional structure. Rice particles were discharged smoothly from the dispenser. When R=180 mm and α=20°, the variation coefficient of uniformity was 24.56%, the variation coefficient of consistency among rows was 3.79%, the variation coefficient of total displacement stability was 1.23%, and the three indicators were all the optimum values. Bench test was carried out using distributors printed by 3D printer and the results showed that the variation coefficient of uniformity for the seed-metering device was 29.17%-30.86%, the variation coefficient of consistency among rows was 4.13%-4.33% and the variation coefficient of total displacement stability was 1.4%-1.7%, which met the requirements of mechanical seeding of rice.【Conclusion】The results from multiple tests are stable and close to the simulation results. The designed air distribution seed-metering device can meet practical requirements, suggesting that using the EDEM-Fluent coupling simulation is correct and feasible.
ZHANG Qingyi , GU Baoxing , JI Changying , FANG Huimin , GUO Jun , SHEN Wenlong
2017, 38(4):117-124. DOI: 10.7671/j.issn.1001-411X.2017.04.019
Abstract:【Objective】 To design a matched online grading system based on the structure and working behavior of the apple harvesting robot,and meet the needs of grading apples in real time. 【Method】The pregrading principle was proposed to eliminate apples with diameters below standard which could improve the grading efficiency. Apple weight was measured by a force sensor and the weight grade was determinated. Apple size and rot area were detected using the machine vision technology. The image processing algorithm and interface control program were developed using Matlab and VS2008. The distributed control network was constructed based on CAN bus. Comprehensive grading tests on apples were performed. 【Result】The determination coefficient of apple actual diameter and detected diameter was 0.990 3, the determination coefficient of the actual weight and test weight was 0.999 6, the determination coefficient of actual rotting area and detected rotting area was 0.985 5. The success rate of comprehensive grading reached 89.71%, and the average grading time per apple was 2.89 s during continuous grading.【Conclusion】The apple grading system is stable, easy to expand, highly efficient and accurate, and can meet the real-time grading needs of the apple harvesting robot.
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