Abstract:In order to explore the adaptability of ground lowcapacity profiling spray technology in tea plantation operation, a tea garden lowcapacity contour spray orbit test system was designed, which was used as a spray carrier. The experimental study on the droplet deposition performance of lowvolume spray on tea garden ground was carried out by orthogonal test method. The structure and control circuit of the spray test system were analyzed. The nozzle installation parameters were determined according to the analytical method. The droplet deposition density and deposition uniformity were taken as the main spray indicators, and the effects of spray height, spray direction, fan speed, nozzle type and canopy gradient on droplet deposition during lowvolume spray of tea tree were investigated. The field experiment results showed that the tea tree canopy gradient had a significant effect on the droplet deposition density, and the number of droplets was decreased from the upper, middle and lower layers of the canopy. The number of droplets in the upper part of the canopy was significantly higher than that in the middle and lower parts, while there was no significant difference in the number of droplets in the middle and lower parts. The spray height was negatively correlated with the number of droplets deposited, and the number of droplets at 30cm was significantly greater than that at 50cm, while there was no significant difference in the number of droplets at 40cm and 30cm and 50cm. The spray direction and the canopy gradient had a significant effect on the uniformity of droplet distribution. When the spraying direction was 45°, the coefficient of variation was 0610, which was significantly greater than the coefficient of variation of 0°, 15°, and 30°, and the uniformity of droplet distribution was the worst. The variation coefficients of 0°, 15° and 30° were not significant. The uniformity of droplet distribution on different canopy gradients was significant. The distribution of droplets in the upper part of the canopy was the most uniform, and the distribution of droplets in the middle of the canopy was the worst. The amount of droplet deposition of the low volume spray was generally small compared with that of conventional sprays. The canopy gradient had a significant effect on the amount of droplet deposition. The average sedimentation volume in the upper canopy was 0.608μL/cm2, which was significantly larger than that in the middle and lower parts, while the difference in droplet deposition between the middle and lower parts was not significant. When the spraying direction was 0°, the mean value of the droplet deposition was the largest, which was significantly larger than that of the 45° direction with the smallest deposition amount. When the tea tree was sprayed at low volume, the average deposition density of each layer of droplets was greater than 26 droplets/cm2, and the coefficient of variation at the top of the canopy was not more than 0.5, which met the requirements of the spraying quality of pesticide sprayers in national standards. The research result provided new methods and new ideas for the reduction of pesticide application in tea tree pest control.
