The Motion of Strawberry Leaves in an Air-Assisted Spray Field and its Influence on Droplet Deposition

Highlights A visualization method for the motion of strawberry leaves in an air-assisted spray field is proposed. Strawberry leaves showed two motion states in different critical velocity ranges of the sprayer airflow. The airflow instability and the turbulence effect are considered important factors for the leaf vibrations. A strawberry leaf azimuth angle in the range of 90° to 270° can provide good deposition with smaller droplets. Abstract. The reasonable motion of crop plants in an air-assisted spray field can improve droplet deposition. Therefore, this study focuses on the motion of strawberry leaves and the droplet deposition mechanism in an air-assisted spray field. First, this study proposes a descriptive method for strawberry leaf motion in an air-assisted spray field and clarifies the important influence of strawberry leaf motion on droplet deposition. Second, an experiment was performed on the motion and droplet capture of single strawberry leaves in multi-position postures in an air-assisted spray field. The results showed that the leaves had two motion states (i.e., low amplitude with low frequency and high amplitude with high frequency) at different airflow velocities and inclination angles, and the critical airflow velocity corresponding to the two motion states was determined to be 8.7 m s-1. When the azimuth angle of the strawberry leaves is in the range of 90° to 270°, a reasonable inclination angle of the airflow and the high frequency and high amplitude vibration state of the leaves driven by the airflow will provide good deposition and canopy penetration of droplets with smaller diameters.