Abstract: A precision seeder for tray nursing seedlings of rice was developed using a new-type pneumatic vibration uniform-seeds device to promote the sowing performance of hybrid rice in low seeding rate. First, steady and uniform seeding condition with different working parameters of the uniform-seeds device was determined, including displacement-storage capacity ratio of air supply, A, setting angle, β, and trapezoidal half difference, C, of the sieving board. Then orthogonal tests were conducted to further investigate the effects of these parameters on the sowing performance, in which the seeding rates were 45 g per tray for supper hybrid rice, 65 g per tray for hybrid rice, and 85 g per tray for inbred rice, respectively. Results show that the best operational parameter combinations were: A was 0.036/40.0 C was 5 mm and β was -4°, 0° and +4° when seeding rates were 45 g per tray, 65 per tray and 85 per tray, respectively. Sowing performance tests based on the best parameter combinations were carried out. The sowing qualified rates were 88.33%, 90.83%, 93.06%, and the cavity rates were 1.76%, 0.56%, 0% for three seeding rates respectively. The sowing performance meets the requirements of precision seeding of super hybrid rice and hybrid rice in low seeding rates.

Key words: agricultural engineering, rice nursing seedlings, rice precision seeder, vibration uniform-seeds device, orthogonal test