Abstract
Winter wheat, usually seeded in autumn, was seeded before continuous snow cover to avoid the overlap between work for wheat sowing and rice harvesting. Then, the optimum seeding date and seeding density were determined. Winter wheat cultivar “Nanbukomugi” was seeded at intervals from early October to late November in 2000 ndash; 2002. The seedlings emerged when accumulative mean temperature above 0°C after seeding reached 95 ndash; 115°C. When the seeding date was early and accumulative mean temperature reached 95 ndash; 115°C before continuous snow cover, frost damage of the seedlings was serious. On the other hand, when seeding date was as late as early to late December, seedlings emerged after overwintering at a high rate, and grew and matured normally. We consider that the suitable seeding date for winter-seeding cultivation in Iwate Prefecture is early to late December. The winter-seeded wheat was inferior to the nomal autumn-seeded wheat in top growth, but had a large number of ears, low lodging frequency and a high grain yield of 379 g/m2, which was 95% of that in autumn-seeded wheat. The appearance quality of the grain was also nearly the same as that in autumn-seeded wheat, and the protein content of the grain was 14.4%, which was 1.4 point (%) higher than that in autumn-seeded wheat. The number of ears increased linearly with increasing seeding density. Grain yield also increased with increasing seeding density, but the maximum yield was 350 grains/m2.
