Among all field operations related to the rice crop, harvesting is one of the most important due to its high cost and also because it directly affects grain yield and product quality. Harvesting demands a great portion of the manual labor required in small farms, where the threshing operations are also performed manually by impacting the plants against a hard surface. Mechanical threshing not only improves labor efficiency but also reduces grain breakage during milling. The objective of this study was to develop and evaluate the performance of three machines designed for threshing upland and lowland rice cultivars, using three different operational procedures: intermittent plant feeding, pedal operated; intermittent plant feeding, motor operated; and continuous plant feeding, motor operated. In the trials, long and short stemmed plants were used as well as grains with different moisture contents. The machine using the intermittent plant feeding system with motor operation, showed greater threshing capacity than the other two. Short stemmed plants produced higher threshing yields when compared to the long stemmed ones.
Oryza sativa; harvest; harvesting machinery; harvesting time
