Objective  In order to meet the agronomic requirements of low sowing rate and precision sowing of hybrid rice potted-seedling raising, and solve the problems of poor fluidity of rice seeds in the seed filling chamber, low seed filling reliability, high missing sowing index and easy blockage of type holes during the operation of seedling raising seeder with type hole roller, a precision seeder with double seed filling type hole roller for hybrid rice seedling raising was designed.

Method  Based on PLC control technology, a detection and control system for type hole seed filling performance was built, and the key components were analyzed and designed. The simulation tests of the influences of the seed filling performance of different type hole shapes, the seed filling position angle of the first seed filling chamber, and the productivity on seed filling performance were carried out through EDEM discrete element software, to optimize the working parameters of the type hole roller in the first seed filling area. The experimental prototype was developed for post performance test, and rice variety was ‘Peizataifeng’ hybrid rice. The test was divided into two steps. In the first step, the second seed filling mechanism did not act, a three-factor-three-level orthogonal test was adopted to study the effects of type hole depth, productivity and seed filling position angle of the first seed filling chamber on the test indexes, and verify the accuracy of the simulation research. The second step was through the action of the second seed filling mechanism to study the effects of different vibration frequencies on the test indexes under double seed filling, and prove the sowing performance after designing the second seed filling mechanism.

Result  The results of the first step showed that the order of factors affecting qualified index and replay sowing index was type hole depth > productivity > seed filling position angle of the first filling chamber; The order of the factors affecting the missing sowing index was productivity > type hole depth > seed filling position angle of the first filling chamber. The results of the second step showed that when the type hole shape was oval groove, the seed filling position angle of the first seed filling chamber was 35°, the vibration frequency of the second seed filling chamber was 27 Hz and the productivity was 400−600 discs/h, the qualified index of sowing was above 90%, and the missing sowing index was below 3%. The test results met the agronomic requirements of low sowing rate and precision sowing of hybrid rice.

Conclusion  The double seed filling method improves the filling performance of each hole of the seeder and reduces the missing sowing index. The results of this study provide references for developing the light and simple precision seeder for hybrid rice potted-seedling raising.