Effects of Seeding Pattern in Direct Seeding of Rice under Submerged Conditions on Grain Yield and its Components in Hokkaido, the Northern Part of Japan

The effects of seeding pattern, namely broadcast seeding (BS), row seeding (RS) with 15, 20 and 30 cm row spacing (RS-15, 20-, 30) and hill seeding (HS) (30 cm row spacing and 10 cm hill spacing) in direct seeding of rice under a submerged condition on the number of tillers, grain yield and yield components were investigated in Hokkaido. Values of the dry weight of individual plants at the establishment stage of seedling (5 leaf stage) and tiller number/m2 and ear number/m2 were higher in BS, RS-15, -20 and were lowest in HS among all seeding patterns. The number of spikelets/m2 was larger in BS and RS-15, and-20, the weight of rice screenings was higher in BS and HS than in the other seeding pattern, and grain yield was highest in RS-15, and-20 about 107-108%of that in RS-30. On the other hand, grain yield in HS was only 96%of that in RS-30. Lodging resistance and blast disease resistance were inferior in RS with narrow spacing. For these reasons, it is concluded that RS-20 is the best seeding pattern in Hokkaido.