Design optimization of an air-suction type seeder for rice breeding plots based on the discrete element method (DEM)

This study designed a novel air-suction seed metering device with a composite structure combining profiled suction holes and groove-based seed-disturbing elements, aimed at addressing the issues of poor seed flowability and low single-seed rate in conventional air-suction rice planters for small plots. Five representative rice varieties from southern China were selected as test materials to determine the key structural parameters. The structure and working principles of the device were analyzed, and the seed disturbance and filling processes were examined through mechanical and dynamic analyses, identifying groove depth, groove inclination angle, and rotational speed as the main influencing factors. Based on DEM simulations, single-factor and orthogonal rotational regression experiments were conducted, followed by response surface analysis and multi-objective optimization. The results indicated optimal performance when the groove depth was 1.45 mm and the inclination angle was 86°. Bench tests were performed using negative pressure, rotational speed, and filling angle as experimental factors, and single-seed rate, multiple-seed rate, and miss-seeding rate as evaluation indices. The optimal combination—negative pressure of 3.61 kPa, rotational speed of 27.52 r·min -1 , and filling angle of 71.77°—yielded a single-seed rate of 86.95% and a miss-seeding rate of 3.73%, meeting industry standards. The generalizability verification tests conducted on five types of rice seeds show that the seed metering device exhibits good sowing adaptability and can meet the sowing requirements of most rice varieties, providing valuable guidance for improving the seeding precision of small-plot rice breeding planters.