Effect of Paddy Moisture Content, Drum Speed and Feed Rate on the Qualitative Losses in a Paddy Axial Flow -Thresher

Since threshing is one of the most sensitive rice post-harvest processing operations, this study was conducted to evaluate the threshing performance in axial - flow paddy thresher. Independent variables consisted of: drum speed at five levels (550, 650, 750 and 850 rpm), equivalent to peripheral velocities of: 14.67, 17.35, 20.01 and 22.37 m/s, respectively, paddy moisture content at two levels (16 and 20% w.b.) plus feed rate at two levels of: 12 and 20 kg/min. Dependent variables were: cracked, broken, and husked grains. The experiment was conducted as a split-split plot one based upon a Completely Randomized Design of three replications. With an increase in drum speed from 550 to 850 rpm, the mean cracked grain loss increased from 6.137 to 8.557% at 20% moisture content and 20 kg/min of feed rate. The loss increased from 8.797 to 18.077% at 16% moisture content and 12 kg/min of feed rate. With an increase in drum speed from 550 rpm to 850 rpm the broken and dehulled grain quantities changed from 0.713 to 1.173% and from 0.823% to 1.447% respectively. The trend indicates the necessity of threshing in higher seed moisture contents, higher drum speeds as well as feed rates.