Airflow-Assisted Pollination in Greenhouse Tomato: Mechanistic Analysis and Airflow Velocity Optimization

Airflow-assisted pollination is an efficient, pollution-free technique for greenhouse tomato cultivation. Optimizing airflow velocity and exploring airflow-driven pollination mechanisms are critical for improving pollination performance and fruit quality. This study integrated numerical simulation, high-speed photography kinematic analysis, and experimental tests to clarify the effects of airflow velocity on tomato pollination. Firstly, computational fluid dynamics (CFD) was used to characterize near-flower airflow fields. Then, high-speed captured floral motion trajectories were imported into discrete element method (DEM) simulations to analyze pollen release behavior. Finally, pollination experiments were conducted to quantify stigma pollen coverage and fruit-setting rate under different airflow velocities. The results showed that airflow velocities of 1.4 to 2.2 m·s−1 generated vortex-shaped airflow around flowers in the simulation model and induced stable floral vibration and improved pollination performance. Accordingly, an inertial pollen detachment mechanism originating from relative motion between pollen grains and anthers was proposed as an interpretation. Moreover, the optimal airflow velocity was determined to be 1.8 m·s−1, corresponding to 13.4% stigma pollen coverage and an 87.8% fruit-setting rate. This study provides a velocity-modulated pollination interpretation and key operational parameters, offering theoretical support for the technical optimization and equipment development of airflow-assisted pollination systems.