Seeding rate, seeding depth, and cultivar influence on spring canola performance in the Northern Great Plains

Rapid expansion of canola (Brassica napus L.) production in the Northern Great Plains has raised questions on the response of cultivars to seeding rate and depth. Field research was conducted at four North Dakota locations in 1999, 2000, and 2001 evaluating a small-seeded open-pollinated (OP) and a large-seeded hybrid (HYB) cultivar at two seeding depths (19 and 38 mm) both at four seeding rates (54, 108, 162, and 216) pure live seed (PLS) m(-2). Percent emergence and plant density was significantly greater at the 19-mm seeding depth compared with the 38-mm seeding depth at six of eight environments. Seeding depth effect on seed yield was inconsistent among environments. Seed yield increased with increasing seeding rates in all but two environments. Hybrid and OP cultivars responded similarly to seeding rate for all characteristics measured, except days to first flower and net economic return per hectare. The net economic return per hectare, based on seed cost and grain value where HYB seed typically costs twice that of OP, was greatest at seeding rates for the large-seeded HYB at 108 PLS m(-2), and at 162 PLS m-2 for the small-seeded OP cultivar. The HYB cultivar had a 24% greater seed yield than the OP cultivar and a 14% greater net economic return per hectare. Producers need to consider cultivar type and seed cost to determine optimum seeding rate to obtain maximum economic return.