Influence of machine-crop parameters on the threshability of sorghum

Abstract

The threshing section on combine harvester or thresher machine affects grain and stalk separation performance.  The present study is conducted with view to optimize important operational and crop parameters influencing the threshing of sorghum.  In this research, the effects of cylinder speed with four levels (13, 17, 21 and 25 m s^-1), concave clearance (5, 10 and 15 mm) and feed rate (420, 500 and 590 kg h^-1) were investigated on  un-separated seed percentage, damaged seed percentage and germination.  Result of ANOVA showed that cylinder speed had a significant effect on unseparated seed percentage and damaged seed percentage (P<0.01).  Concave clearance created a significant effect on damaged seed percentage.  Though the feed rate did not have significant effect on all adjectives, the unseparated seed percentage increased with increasing of feed rate.  The thresher efficiency and damaged seed increased with increase of cylinder speed.  The increase of Concave clearance from 5 to 10 mm caused that unseparated seed weight percentage increased from 0.69% to 0.78%, and damaged seed rate decreased from 13.01% to 11.01%.  Generally, the best performance for sorghum threshing was given at the 21 m s^-1 cylinder speed, 10 mm Concave clearance and 590 kg h^-1feed rate.

Keywords: sorghum, threshing quality, cylinder thresher