Optimizing Herbicide Application Parameters in Rice Using UAVs : Performance and Comparison With Conventional Technologies

ABSTRACT

Unmanned aerial vehicles (UAVs) are increasingly considered a promising alternative to conventional ground‐based herbicide application in rice production systems; however, their effectiveness depends strongly on optimizing operational parameters that influence spray deposition, biological efficacy, and crop response. Field experiments were conducted during the 2023–2025 growing seasons in the Marmara and Black Sea regions of Turkey to (i) identify optimal UAV application parameters for effective weed control and (ii) compare the performance of optimized UAV spraying with that of conventional ground‐based application in rice. A factorial experimental design was used to evaluate the effects of UAV flight height (1.5, 3, 4, and 5 m), flight speed (4.4, 5.5, and 6.6 m s ⁻¹ ), and spray volume (20, 30, and 40 L ha ⁻¹ ) on spray area coverage, weed control efficacy, weed dry weight, crop phytotoxicity, tiller number, and grain yield. Spray area coverage was significantly influenced by all UAV operational parameters and their interactions; however, maximum coverage at the lowest flight height did not result in improved weed control. Weed control efficacy and weed dry weight reduction were optimized at a flight height of 4 m, particularly at a flight speed of 5.5 m s ⁻¹ and spray volumes of 30–40 L ha ⁻¹ . Grain yield was significantly affected by UAV parameters and region, while year effects were not significant, indicating the robustness of the optimized application strategy across seasons. Using the optimal UAV settings (4 m flight height, 5.5 m s ⁻¹ speed, and 30 L ha ⁻¹ spray volume), weed control efficacy exceeded 90% and weed dry weight was reduced to levels comparable with those achieved by conventional application at 300 L ha ⁻¹ , despite significantly lower spray area coverage. Overall, the results demonstrate that properly optimized UAV‐based herbicide application can provide effective, stable, and integrated weed control in rice while substantially reducing spray volume and improving application efficiency.