2002 Volume 71 Issue 3 Pages 308-316
To clarify the effect of unevenness in a field on the tiller development of direct-seeded rice plants, we investigated the height and growth at the same measuring points. The paddy field had a high degree of evenness, but plant length was negatively correlated to the height within the undulations of less than ±2cm or ±3cm. Water depth after seedling establishment averaged 2.5cm in 1998, and the undulations influenced on the emergence percentages of tillers from the second and third node on the main stem, i.e., T2 and T3. In 1999, the mean water depth of 5.9cm, the emergence percentages of T3 and T4 were negatively correlated to the height within the undulations of less than ±3cm or ±2cm. These suggested that the deeper water, because of unevenness and water management, reduced the emergence percentages of the tillers. Furthermore it was evaluated from our other experiments that the emergence percentages could be altered by the developmental differences at watering. The higher percentages of T2 and T3 did not produce more stems per plant at maximum number tiller stage, and the percentage of plants with a tiller from the first node of T2 was less than 26%. These results showed that the emergence of secondary tillers from T2 or T3 was probably suppressed.
