Studies on the cultivation of spring wheat seeded in early winter in Central Hokkaido - Effect of the method of nitrogen application on the yield and protein content [Japanese]

摘要

Spring wheat was sown in early winter, and the suitable amount and application timing of nitrogen (N) fertilizer to obtain both high yield and high protein content in the grains were examined. N fertilizer of 0-16 g N m(-2) in total was applied in a lump just after snow melting, or in divided doses once just after snow melting (4-13 g N m(-2)) and once at flag-leaf emergence stage (3-6 g N m(-2)). In the plants supplied with 10 g N m(-2) in total, which is optimum for spring seeding, the plants seeded in early winter showed nearly the same N absorption as those seeded in spring, but higher biomass and higher harvest index resulting in higher yield than those seeded in spring. The increase of N supply for the plants seeded in early winter increased N absorption, biomass, harvest index, yield and protein content. In the plants supplied with N fertilizer in divided doses, the yield was lower but the protein content was higher than in those supplied with the same amount of N in a lump. However, we considered that the application of 7-10 g N m(-2) just after snow melting and 3-6 g N m(-2) at the flag-leaf emergence stage is better to increase the yield protecting the lodging and increasing the protein content that are desirable for bread and soy-sauce making.