Abstract
To cultivate waxy rice instead of transplanting by direct sowing in Hokkaido, we investigated the germination, emergence and establishment of waxy rice (cv. Hakuchou-mochi and cv. Kazenoko-mochi) under artificial or natural conditions, and also investigated the growth and yield of waxy rice (cv. Hakuchou-mochi) by machinery direct sowing in a well-drained paddy field from 1998 to 2001. The rates of germination and emergence of the two cultivars of waxy rice under artificial conditions were higher than those of nonwaxy rice (cv. Yukimaru) that was used for direct sowing. In the paddy field, the establishment percentages of the waxy rice were slightly inferior to or nearly the same as those of the nonwaxy rice under shallow seeding depth conditions. In the case of deep seeding conditions, the establishment percentages of the waxy rice were higher than those of the nonwaxy rice. The establishment of the waxy cultivar sown with a up-cut rotary seeder in a well-drained paddy field was 32 to 56%, and the number of establishment was 159 to 234 seedlings per m2. When the seeds not coated with oxygen supplier (calcium peroxide) were used, the number of established seedlings decreased. The heading and maturity stage of the waxy rice directly sown at a suitable seeding time were 2 to 6 days and 0 to 2 days later, respectively, than those of transplanted waxy rice. The yield of directly sown plants was 86 to 115% of that of transplanted plants, and late sowing greatly decreased the yield except in 1999. The number of established seedlings was correlated with that of panicles, and the panicle number was higher in the directly sown plants than in the transplanted plants. Because yield increased as the panicle number increased, it is important to increase the number of established seedlings for increase of the yield. However, the yield was also affected by meteorological conditions. For the introduction of direct sowing of waxy rice to Hokkaido instead of transplanting, it is necessary to consider the delay of heading and maturity stage.
