Mohammad Amin Nematollahi - Biosystems Engineering Department, College of Agriculture, Shiraz University, Shiraz,. Iran
Mohammad Amirhajloo - Biosystems Engineering Department, College of Agriculture, Shiraz University, Shiraz, Iran
Seyed Hosein Karparvarfard - Biosystems Engineering Department, School of Agriculture, Shiraz University, Shiraz, I.R. Iran
Mehdi Moradi - Biosystems Engineering Department, School of Agriculture, Shiraz University, Shiraz, I.R. Iran
hadi azimi-nejadian - Biosystems Engineering Department, College of Agriculture, Shiraz University, Shiraz, Iran

In the present study, the application feasibility of an air-assisted centralized metering device equipped with a fluted feed roller was investigated. The performance of the proposed metering device for rapeseed planting was evaluated in the laboratory. For this purpose, effects of rotational speed (n) of the metering device shaft (at levels of ۴۶.۵, ۴۸, ۷۹, and ۹۶ rpm), active roller length, L, (at levels of ۱/۶, ۱/۴, and ۱/۳ of the total length of the fluted roller), and number (N) of seed delivery tubes (at levels of ۱۶, ۲۴, and ۳۲ outlets) on the seed weight delivery coefficient of variation (CV) and seeding rate (SR, kg ha-۱) were investigated. A factorial experiment arranged as a completely randomized design with three replications was used to perform the laboratory experiments. Results showed that the effects of all treatments (n, L, and N) on both SR and CV were significant. The interactions of N×L and L×n were also significant on both SR and CV. The interaction of N×n was significant only on the SR. The interaction of N×L×n was also significant on the SR. Results of mean comparisons revealed that the CV decreased as n and L increased; whereas, it increased as N increased. However, the opposite pattern was observed for the SR with changing the mentioned factors. Minimum SR value (۶.۱ kg ha-۱ – in the recommended SR range for rapeseed planting) was obtained at ۴۶.۵ rpm and L۱ (۱/۶ of the total length of the fluted roller) with ۳۲- outlet seed delivery tube.

Coefficient of variation, Grain drill, Metering device, Rapeseed, Seeding rate