INFLUENCE OF TIMING AND METHOD OF HARVEST ON RAPESEED YIELD

A critical step in production of winter rapeseed (Brassica napus L.) in humid environments is seed harvest. This 3-yr study (1986 to 1989) evaluated the effect of harvesting method, harvester type, and seed color stage on seed yield of three rapeseed cultivars ('Westar', 'Cascade', and 'Bridger') near Tifton, GA. No consistent trends were exhibited by swathing or direct combining rapeseed. Seed yield was influenced by weather conditions and crop stage rather than harvesting methods. Both harvesting methods seem potentially acceptable for rapeseed production in the Southeastern USA; however, the added input requirements for swathing may reduce the economic potential for this practice. A draper table-type combine significantly reduced seed yield losses when compared with an auger-type combine. Auger-type combines may need modification to reduce potential seed losses. Mechanical losses reduced total seed yields from 21 to 66%. The best machine-harvested rapeseed yields were obtained in 1988-1989 with a draper table-type harvester, either directly combining at 70 to 90% of dark seed (average yield for all cultivars of 1427 lb/acre) or swathing at 50 to 70% of dark seed (average yield of 1294 lb/acre).