A study was conducted at PAU Regional Research Station, Gurdaspur (Punjab) to investigate the design and operational parameters of threshing mechanism of conventional combine harvester for basmati crop. This study was aimed to investigate the suitable changes required in the self-propelled conventional combine harvester for harvesting the basmati crop with minimum grain losses. Field evaluation of experiment was carried out to assess the influence of independent design variable i.e., arrangement of spikes (AS) and independent operational parameters such as concave clearance (CC) and cylinder speed (CS). The study was aimed to enumerate various combining losses viz., extent of visible and invisible grain damage and threshing efficiency at different AS, CC and CS levels. The first year data recorded during 2017 were processed for the optimization during 2018. The results of the present study revealed that during 2017, maximum visible and invisible losses was 5.49% ± 0.33% and 28.07% ± 3.21%, respectively whereas after modification, these losses remained only 4.00% ± 0.80% and 24.07% ± 2.86%, respectively. The threshing efficiency remained above 99.31% ± 0.47%, for both years. Thus, optimization of combine harvester was able to save the visible grain damage by 60% to 83% and invisible grain damage by 6% to 16%, respectively during 2018 than the year 2017.

Among all the food grains, Basmati rice (Oryza sativa) has significant export potential. At present, majority of harvesting and threshing of basmati is accomplished manually because of high quality of grain. Manual harvesting and threshing operation is quite costly and mostly done by hired labour, threshing cost and family labour. Labour in harvesting has become scarce due to industrialization. The commercially available machines for paddy harvesting and threshing are not suitable for basmati varieties because of relatively delicate nature. There is no data available regarding design and operational parameters for harvesting basmati with conventional combine harvester. Therefore, this study has been planned to study the effect of selected design and operational parameters of threshing mechanism of conventional combine harvester for basmati crop and to compare the performance with prevalent practice. Field evaluation of experiment was carried out to assess the influence of independent design variable i.e., arrangement of spikes (AS) and independent operational parameters namely concave clearance (CC) and cylinder speed (CS). The study was aimed to quantify various combining losses viz., extent of grain damage (visible and invisible), unthreshed and clean grain losses in straw walker at different arrangement of spikes, concave clearance and cylinder speed. Initial testing of conventional combine harvester on PUSA Basmati-1121 to reduce the visible as well invisible losses had been carried out at PAU Regional Research Station, Gurdaspur (Punjab) during the year 2017.