Study of the Affecting Factors on the Performance of Precision Pneumatic Cylindrical Distributor for Sowing Thyme Seed

Pneumatic precision seeders are used for sowing of cereals. However, sowing small uncoated seed of medical plants is very difficult by these seeders. The purpose of this study was to investigate the performance of the pneumatic cylinder distributor to sow uncoated thyme seed and to determine its optimal conditions. The effects of four factors were investigated: the suction pressure at -6, -8, -10 kPa, the linear velocity of distributor at 3, 4, 5*10-2 m. s-1, the diameter of the distributor hole at 5, 7*10-4 m and the seed hole shape in conical and straightforward forms. In order to estimate the distributor yield, three indices of miss index, multiple index and quality of feed index for thyme were examined. The experiments were performed in 5 replications by the factorial method in a completely randomized design. The results showed that the suction pressure and linear speed of the distributor had a significant effect on the indices. The best performance of the distributor unit was obtained at -10 kPa pressure, 3*10-2 m. s-1 linear speed of the distributor, 7*10-4 m diameter for the distributor hole and the shape of the conical hole. Under these conditions, the values of miss, multiple and quality of feed indices resulted in 0.4%, 4.4%, and 95.2%, respectively.