Abstract
Tillers with two or more leaves just before snow (robust stems before wintering, RS) affect the ratio of effective tillers and the yield in winter wheat in Hokkaido. The relationship between the number of RS per plant and the leaf age shown by the number of leaves on the main stem before wintering (LA) was investigated; then the desirable LA for increasing the yield was estimated. There was no significant difference between the number of RS and stem length, but the yield components, number of ears per plant, grain weight per ear and number of grains per panicle, were significantly greater in the plants with a larger number of RS. Although there was no significant corelation between cultivation condition and the number of RS, the plants at LA5.0, 5.5 and 6.0 had 3, 4 and 5 RS, respectively. The seeding density of the plants at LA5.5 and 6.0 was 167 and 132 grains/m-2, respectively. From the viewpoint of using the seeding machine, stable seeding at a rate of 132 grains/m-2 would be difficult. The results indicated that LA affects the yield of winter wheat in Hokkaido, and the desirable LA is around 5.5.
