Effect of sowing date and increasing sowing rates on plant density and yield of winter oilseed rape (Brassica napus L.) under Nordic climate conditions

Abstract

A five-year investigation on overwintering of winter oilseed rape (Brassica napus L.) cv. Wotan has been carried out in Estonia. Sowing in August was conducted four times at weekly intervals. Seeding rates of 100, 150, and 200 plants m-2, at which respectively 47, 71, and 98 plants overwintered, gave different densities at harvest. A lower plant density (47 plants m-2) produced yields just as high as those with higher density (98 plants m-2). The optimal sowing date was mid August, which gave on average 98 plants m-2 with various plant densities. Those plants also gave higher yield (1748 kg ha-1), compared with the plots sown early or later in August. © 2008 Taylor & Francis.