Impact of sprayer drone flight height on droplet spectrum in mountainous coffee plantation

ABSTRACT Weather conditions and sprayer operating parameters influence spray quality. Unmanned aerial vehicles are considered a modern, useful, and very efficient technological tool in the application of pesticides, as they carry out punctual spraying, and reduce environmental and public health problems. The objective of this study was to characterize the spraying quality carried out with an unmanned aerial vehicle as a function of flight height and target position in a coffee plantation in a mountainous region. Three flight heights (2.5, 3.0, and 4.0 m) were used, and the targets were placed at the top and bottom of the plant. For each plant, six water sensitive papers were placed on top of the plant and six were placed at the bottom. CIR 1.5 software was applied to determine the coverage percentage, drop density, volume median diameter, volumetric diameter corresponding to 10 and 90%, numerical median diameter, and relative amplitude. The results showed that the flight height only influenced the parameters of the volumetric diameter corresponding to 10% of the volume, numerical median diameter, and coverage percentage. The target position on the canopy influenced all the evaluated spraying parameters. In mountainous coffee plantations, the spraying system using unmanned aerial vehicle spraying is more efficient for the lower part of the plant.摘要：气象条件与喷雾器作业参数会影响喷雾质量。无人机（Unmanned Aerial Vehicle, UAV）被视为农药施用领域中一款现代化、实用且高效的技术工具，因其可实现精准喷雾，同时能够减轻对环境与公众健康的危害。本研究旨在针对山区咖啡种植园中的无人机喷雾质量，以飞行高度与靶标位置为变量开展表征分析。本实验设置3组飞行高度（2.5 m、3.0 m及4.0 m），并将靶标放置于咖啡植株的顶部与底部；每株咖啡植株的顶、底两侧分别放置6张水敏试纸（water sensitive paper）。采用CIR 1.5软件测定以下参数：覆盖率、雾滴密度、体积中径、体积累积占比10%与90%对应的体积粒径、数量中径以及相对跨度。结果表明，飞行高度仅对体积累积占比10%对应的体积粒径、数量中径及覆盖率这三项参数存在显著影响；植株冠层上的靶标位置则对所有被测喷雾参数均有显著影响。在山区咖啡种植园中，采用无人机喷雾系统对植株底部进行喷雾的效率更高。