Abstract
Tiller production of rice plants (cv. Kinuhikari) transplanted at different seedling numbers per hill (1, 3, 5, 7 and 9 seedlings per hill) was examined in 1994, a hot and sunny year. Tillering duration decreased with increasing number of seedlings per hill (density), and that in the 9-seedling hills was two weeks shorter than that in the 1-seedling hills. The higher the seedling density, the earlier was the time of tillering. In 1 to 5-seedling hills, the tiller production rate increased with increasing seedling density, but the rate decreased in the hills with higher seedling densities. Primary tillers emerged at the third (T3) to the ninth node (T9) of the main stem in 1-seedling hills, at T3 to T9 nodes in 3-seedling hills, and at T3 to T7 nodes in 5, 7and 9-seedling hills. Heading duration was 8—9 days in 5, 7and 9-seedling hills and 10—12 days in 1 and 3-seedling hills. The number of spikelets per panicle decreased with increasing seedling density, and the largest panicles on primary tillers were formed on the tillers at T7, T6, T5 and T4 nodes in 1, 3, 5, 7 and 9-seedling hills, respectively. These results suggest that, in hot and sunny years, seedling number per hill affects the tillering time, tiller number, heading time and panicle size on each nodal tiller.
