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Copyright of Journal of Nanjing Agricultural University / Nanjuing Nongye Daxue Xuebao is the property of Journal of Nanjing Agricultural University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Smart Agriculture is the property of Smart Agriculture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Smart Agriculture is the property of Smart Agriculture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thinning is one of the three labor-consuming sections (pruning, thinning and harvesting) in orchard management process. Chemical thinning, not only unstable but also reduces fruit safety, has been banned gradually in recent years. Pure artificial thinning, especially artificial fruit thinning, needs larger workload and higher labor cost, unsuitable seriously for the requirements of modern orchard planting. Two kinds of pear mechanical flower thinners were designed in the paper. They were three arms tractor-mounted flower thinner (TMFT) and hand-held flower thinner (HHFT), to alleviate the heavy labor pressure in the process of thinning and improve the efficiency of orchard operation. The width of TMFT was controlled by hydraulic cylinder that range from 1.2 to 1.7 m. TMFT rotation speed of thinning shaft that range from 0 to 300 r/min was controlled by electronic governor. The length of HHFT can change through adjusting the extension rod that range from 0.95 to 1.6 m. HHFT rotation speed of thinning shaft that range from 0 to 900 r/min was controlled by electronic governor too. ‘Y’ trellis ‘Cuiguan’ pear was taken as the research object in the paper. TMFT impact forces of thinning rope with different rotation speed of thinning shaft and thinning distance were measured in bench test, to find the working range of rotation speed. Field test setting 50% flower bud preserved rate (it is easier to thin flower buds than flowers) and 0.44 m/s tractor work speed, and the best rotation speed of thinning shaft was ensured: 254 r/min. Flower bud reserve rate, fruit set rate, work efficiency, fruit yield and quality of four kinds of operation methods were tested, which were TMFT combined with artificial fruit thinning, HHFT combined with artificial fruit thinning, artificial flower fruit thinning and artificial fruit thinning only. Twenty-four ‘Y’ trellis pear trees (6 a) with almost same size were selected for four operation methods. The canopies of each tree were divided into the upper middle lower three layers and five branches were selected as samples in each layer. In order to reduce the operation error, except the TMFT, the operation of each group was completed by two workers with experienced job skill. Field test show that three flower thinning methods can meet the requirement of 50% flower bud preserved rate, the coefficient of variation all less than 15%. There is no obvious difference between TMFT and artificial method in thinning quality and the stability of TMFT is the highest among test groups. Mechanical and artificial flower thinning can significantly reduce about 50% absolute fruit set rate. TMFT will damage the young fruits in a certain degree, but does not affect the yield and quality in the last. Work efficiency of TMFT was highest among flower thinning methods and 66.17% artificial fruit thinning time can be saved. TMFT has a higher requirement for pear orchard mechanization degree, suitable for large-scale mechanized pear orchard. Work efficiency of HHFT is second only to TMFT, 37.26% artificial fruit thinning time can be saved. HHFT is suitable for small and medium sized pear orchard. For fruit yield and quality, total and high quality fruit yield per tree of pure artificial fruit thinning group is higher 11.37% and 8.59% respectively than average values of three kinds of flower thinning group, but the average weight of high quality fruit and brix of sugar solids of is lower 6.58% and 1.55% respectively. The research is helpful to improve the working quality of flower thinner and provide reference for the mechanization management of pear orchard. [ABSTRACT FROM AUTHOR]

Air-assisted orchard sprayers are characterized by a strong airflow that carries the pesticide droplets to the target canopy and assists the plant parts to move so as to allow the whole tree penetrated with pesticide droplets. The airflow distribution and movement characteristics are key parameters of sprayer for droplet deposition on target canopy. In order to study the 3D (three-dimensional) spatial distribution of airflow field from an air-assisted orchard sprayer, this article used ICEM CFD (Integrated Computer Engineering and Manufacturing code for Computational Fluid Dynamics) to establish a geometric model, whose whole structure was meshed, and the k-ε turbulence model and CFX solver were adopted. The effect of different environmental systems on airflow 3D distribution for air-assisted orchard sprayer was estimated, in which the upper deflector angle was set as 30°, 45°, 60°, and 90°, and the lower deflector angle was set as 0°, 10°, 20° and 30°, respectively. Results show that the 3D spatial distribution model of the airflow from air-assisted orchard sprayer can reflect the airflow distribution directly, and the simulated values of airflow characteristic curve are in good agreement with the measured values. However, in the low airflow velocity region (the velocity below 2 m/s), the simulated velocity values of some sampling points are quite different from measurements. That is caused by the perturbation of the natural wind. In the high airflow velocity region with 1.2 m width, the average relative error between the measured value and the simulated value of wind speed is less than 10%. That can confirm that the simulation results are credible. Meanwhile, airflow guided by deflectors is mainly focused in the area the deflectors pointed to, with no obvious effect on airflow diffusion in the middle area, only increasing the airflow velocity and letting airflow gather near deflector area. So the adjustment of deflector angle should be based on the height of canopy and tree trunk, through setting lower deflector angle to fit the foliage limit of the orchard, and setting upper deflector angle to point at position which is little lower than the topmost of tree canopy in the orchard. For further research, to change airflow velocity of the fan has no significant effect on airflow distribution in the airflow field, and merely increases airflow diffusion region. When the lower deflector angle increases from 0° to 30°, the effect of ground friction resistance on the airflow decreases gradually, and the angle between ground friction resistance and air resistance on both sides increases constantly, so one single air current is divided into 3 air currents gradually. This kind of air distribution on horizontal plane has advantages on blowing branches and leaves and penetrating droplets into fruit tree canopy. The airflow velocity distribution in the vertical direction considerably affects the distribution of spray droplets in canopy. The vertical profile of the airflow velocity should be even along the whole vegetation wall, and matched with the canopy shape curve. But the deflector can only adjust the upper and lower airflow, some deflectors are suggested to be fixed in the middle area for adjusting airflow distribution in vertical direction. This study found that a better effect could be achieved by setting the upper and lower deflectors angle as 30° for spraying in the Chinese general orchard where fruit trees had 3.0-3.2 m height and were planted with 4 m row spacing, and by setting the upper deflector angle of 90° (or removing), and the lower deflector angle of 30° for spraying in trellised orchard. The results can provide the reference for the spraying in the orchard, and the higher spraying efficiency and the reduction of environmental pollution can be achieved through the calibration of sprayer operational parameters. [ABSTRACT FROM AUTHOR]