Design and testing of the self-sequencing rice transplanter

Mechanical seedling throwing and nursery raising can be confined to low efficiency and high labor intensity in rice cultivation. In this study, a self-sequencing rice transplanter was proposed using dynamic uniform seedling regulation. The modules were also integrated with micro-feed seedling pushing, flexible oblique cutting for seedling combing, tandem uniform seedling distribution, and wind-assisted seedling delivery. The multi-module control system was fully coordinated for the rice planting with high precision, efficiency, and flexibility. The mobility system utilized a tracked chassis with a ground pressure of 20.8 kPa. Stable performance was achieved under varied field conditions, including wet and uneven terrain. Execution mechanism comprised three adaptive units: a flexible seedling-combing device, a two-stage uniform seedling distributor, and a high-speed seedling-blowing unit. Each component was designed to dynamically adjust its operational parameters in response to real-time field and seedling conditions, indicating high adaptability and output consistency. Seedlings were continuously drawn from the storage bin using the combing device and then transferred onto a conveyor system. Two-stage dynamic uniform seedling mechanism then redistributed them evenly before the blowing unit accelerated the seedlings into the air, thus extending their trajectory for the proper penetration and spacing in the soil. An integrated intelligent control system continuously monitored seedling supply levels and planting effectiveness, providing for actionable feedback after adjustment and optimization. The dimensions of the self-sequencing rice transplanter were 3.5 m × 2.4 m × 2.5 m (length × width × height), and the total weight was 2 400 kg. Field trials were conducted in the Quyuan Management District, Miluo City, Hunan Province, China, in April 2025. A three-replicate comparison was conducted to validate the prototype's performance using mechanical throwing and transplanting. The results show that the wide seedling adaptability was achieved in the seedlings with a height of 8-20 cm and a substrate moisture content of 15%-25%. Compared with the current mechanical transplanting, the overall efficiency of the machine increased from 0.6 to 1.0 hm²/h, and the number of workers for manual assistance was reduced from 3 to 1. The seedling raising was simplified to alleviate the cropping schedule tension in double-season rice systems. The planted seedlings exhibited a shortened recovery period, rapid regreening, early and abundant tillering, and a high panicle formation rate. An operational efficiency of 1 hectare per hour was equivalent to the daily workload of a skilled farm laborer, significantly reducing production costs. The working width was adjustable from 4 to 7 m, the seedling throwing distance was adjustable from 4 to 8 m, and the travel speed ranged from 0 to 2 m/s, thus allowing flexible adaptation to planting density requirements for early, middle, and late-season rice varieties. Equipped with a human-machine interactive control system, one-touch start-stop adjustment of parameters was realized for a single operator to complete all tasks. The full growth period was 110 days for machine-thrown rice, compared with 115 days for machine-transplanted rice, thereby representing a reduction of 5 days. The average yield was 7.93 t/hm² for machine transplanting, while the average yield reached 8.52 t/hm² for machine throwing, with an increase of 6.95%. Strong promotion potential: compatible performance with conventional seedling raising and throwing, good adaptability in southern rice-growing regions, and mitigation of labor shortages. Key components can also be optimized to enhance performance and reliability. Maturation and widespread promotion can also be expected to bring revolutionary changes into mechanical transplanting in rice cultivation.