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| 1 | Performance evaluation of mechanical blossom thinning in trunk type pear orchard显示文摘In order to yield a marketable product,hand fruit thinning(HFT)has become the major but costly management practice in modern pear planting.Two kinds of new blossom thinners for pear blossom thinning were developed,which are tractor-mounted three arms blossom thinner(TTBT)and hand-held electric blossom thinner(HEBT).Four treatments for 24 trunk type‘Cuiguan’pear trees(7 years)were tested.They are TTBT combined with HFT,HEBT combined with HFT,hand blossom thinning(HBT)combined with HFT,and HFT only.Pear trees were divided into 4 groups equally.Four indexes were used to evaluate the test:flower reserve rate,fruit set rate,work efficiency and cost,fruit yield,and quality.Pear canopy was divided into the inner,middle,and outer 3 layers in the top view.20 inflorescence samples were selected for each layer.Field tests showed:there was no obvious difference in quality between mechanical blossom thinning and HBT,and the working stability of TTBT was higher than other treatments.Mechanical blossom thinning decreased the fruit set rate to a certain degree,but did not reduce the yield and quality of harvesting.TTBT could save 61.35%operation time compared with HFT,and the profitable area was 5845.76 m2.TTBT is suitable for large-scale sparse layer trunk-type pear orchards.HEBT could save 36.01%operation time compared with HFT,and the profitable area was 663.96 m2.HEBT is suitable for small and medium-sized trunk-type pear orchards.Blossom thinning can improve the average weight of high quality fruit and brix of sugar solids. | Xiaohui Lei Xiaolan Lyu Meina Zhang Daipeng Lu Shilin Wang Youhong Chang Dexin Zhong Tianbing Shen | 2021 | International Journal of Agricultural and Biological Engineering2021，14，4： | 1 |
| 2 | Tunnel-convective air-assisted spraying technology for improving droplet deposition on hedgerow vines显示文摘Given the impermeability,larger dosage,and higher drift of pesticides used in modern hedgerow vine canopies,a novel tunnel-convective air-assisted spraying technology was proposed.Mechanized spraying equipment with high penetration and low drift was developed.The air-assisted system of this equipment was centrosymmetric,and the fan type was cross-flow.The fan outlet width was 138 mm and the air duct’s main body followed a logarithmic spiral profile,based on parallel flow theory.The external diameter of the impeller was 157 mm,which was fixed into a barrel structure by 23 strong forward-curved blades,each being 1 mm thick.The central angle of the blades was 108°,and the ratio of the internal and external diameters was 0.81.The impeller and air duct served as guides to circulate and reciprocate airflow around the crown,forming a tunnel-convective air-assisted to the vine.Using MATLAB interpolation,the airflow trajectory of the air convection circulation in the door-shaped cover was obtained.The velocity field distribution test showed that,in the case of a canopy,there were tunnel-convective circulating airflows with high velocity on both sides and uniform velocity in the middle of the canopy.Due to the tunnel-convective air-assisted spraying technology,the vertical distribution uniformity of spray deposition has been significantly improved,spray penetration has been enhanced,penetrability has been effectively improved,and droplets on the ground and in the air have been significantly reduced.The results of this study can assist in providing further optimization and improvement of plant protection machinery.The new tunnel-convective air-assisted spraying technology may be a more favorable choice for future spray applications and the environment. | Zhenjie Wen Wei Qiu Zhentao Zhang Weimin Ding Xiaolan Lyu Fiaz Ahmad Hui Wang | 2021 | International Journal of Agricultural and Biological Engineering2021，14，6： | 0 |
| 3 | Development of unilateral obstacle-avoiding mower for Y-trellis pear orchard显示文摘To solve the problem of weeding under Y-trellis pear orchards,a unilateral obstacle-avoiding mower(UOAM)was developed in this study.The mower is composed of an obstacle-avoiding disc mechanism,a hydraulic profiling mechanism,and a cutting disc mechanism.The diameter of the obstacle-avoiding disc was 0.7 m,which could swing around the trunk or ground pile actuated by the spring mechanism.The piston movement of the hydraulic cylinder controls the working position of the obstacle-avoiding disc.The maximum extension distance of the hydraulic profiling arm was 1 m.Based on the national standards and actual situation of orchards,the optimum parameters were determined with a combination of advancing speed of 0.44 m/s,rotation speed of the cutting disc at 2000 r/min,blade number of 2,and cutting edge length of 0.2 m.Finally,the design parameters were verified by the mathematical model of the blade cutting edge trajectory and multi-body dynamics simulation.Taking stubble cutting stability,leakage rate,working efficiency and costs as the test indexes,field performance comparison tests were carried out on the three operation modes of UOAM mowing,shoulder carrying mower(SCM)mowing and manual weeding.Test results showed that the coefficient variation of stubble cutting height of UOAM was the smallest,showing that the working stability of UOAM was better than the other two treatments.The leakage rate of UOAM was 2.42%,and its coefficient variation was lower than that of SCM.The working efficiency of UOAM was much higher than that of SCM and manual weeding,which was 4.44 times of SCM and 20 times of manual weeding.The profitable area of UOAM was 7.02 hm^(2),showing that it was suitable for large-scale mechanized Y-trellis pear orchards. | Xiaohui Lei Yannan Qi Jin Zeng Quanchun Yuan Youhong Chang Xiaolan Lyu | 2022 | International Journal of Agricultural and Biological Engineering2022，15，1： | 0 |
| 4 | Design of a fixed-pipe cold aerosol spraying system for chemical application in greenhouse显示文摘Since the high temperature and humidity in a closed environment,pests and diseases are infecting and spreading seriously in greenhouses.However,the prevention and control of pests and diseases in greenhouses are still dominated by knapsack sprayers.For those reasons,based on twin-fluid atomization,droplet dispersion,and constant pressure transportation technique,a fixed-pipe cold aerosol spraying system composed of the control unit and the fixed-pipe spraying unit comes into being.The indoor pipeline execution unit of the spraying system could be interfaced with the liquid-supply or gas-supply equipment such as the liquid pump,air compressor,and tank of the outdoor master control unit through a quick coupling,which could realize the separation of operator and sprayer in hermetic greenhouse.The atomization of twin-fluid nozzle and the droplet deposition and distribution of the spraying system in greenhouse were tested.Results showed that about 70%of the particle size of the twin-fluid flow nozzle concentrated in the range of 32-65μm under the spraying air pressure ranged from 0.2 MPa to 0.4 MPa.When the air pressure was 0.2 MPa,0.3 MPa,and 0.4 MPa,the wind speed at the nozzle outlet reached supersonic speed,as the corresponding VMD of droplets were 45.6μm,43.2μm,and 36.8μm,respectively.The higher the air pressure is,the more uniform the spray deposition is in the greenhouse.When the air pressure was 0.2 MPa,0.3 MPa,and 0.4 MPa,the CVs of the liquid deposition in the greenhouse were 109.1%,62.6%,and 35.4%,respectively.The droplets produced by the spraying system will rapidly disperse into the whole greenhouse.The average deposition was 2.99μL/cm2 in the front area of the nozzle,the deposition was 1.24μL/cm2 in the area between two nozzles,and the deposition was 0.58μL/cm2 in the area behind the nozzles.The spraying system is characterized by the distribution of spraying liquid throughout the entire greenhouse. | Shilin Wang Daipeng Lu Xue Li Xiaohui Lei Yuxin Tang Xiaolan Lyu | 2023 | International Journal of Agricultural and Biological Engineering2023，16，1： | 0 |
| 5 | Comparative DNA-methylome and transcriptome analysis reveals heterosis-and polyploidy-associated epigenetic changes in rice显示文摘Heterosis and polyploidy have an overwhelming influence on plant evolution.Recently,polyploid rice hybrids have been used to breed new rice varieties because they combine the advantages of both heterosis and polyploidy.In this study,we generated six rice lines:autotetraploid rice hybrids and their autotetraploid parents,diploid donors,and hybrids of the diploid donors.To investigate the molecular mechanism controlling the effects of both hybridization and polyploidization,we performed bisulfite and RNA sequencing on young panicles at the pollen meiosis stage to compare the DNA metabolomes and transcriptomes among the six rice lines.The hybrids lines were hypermethylated compared to their corresponding parents and the autotetraploid lines showed globally increased DNA methylation of their transposable elements compared to the diploid donors.The alteration in DNA methylation level corresponded to the differential gene expressions among the rice genotypes,suggesting that methylation changes induced by polyploidization and hybridization may affect gene expression.Groups of gene candidates were identified that may be associated with heterosis and polyploidy.Our results provide DNA information that can be used to investigate epigenetic modification during heterosis and polyploidy in rice. | Xiaolan Rao Jun Ren Wei Wang Rongrong Chen Qian Xie Yanqing Xu Dongmei Li Zhaojian Song Yuchi He Detian Cai Pingfang Yang Shiyou Lyu Li Li Wei Liu Xianhua Zhang | 2023 | The Crop Journal2023，11，2： | 0 |
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