Abstract
Studies on the correlation of seedling density with the nodal position of the last visible primary tiller on the main stem is necessary for modeling of crop growth and development, because the potential number of cumulative total tillers per plant is determined by the nodal position of the last visible primary tiller. The nodal position of the last visible primary tiller on the main stem was negatively correlated with the seedling density irrespective of year in both Dontokoi and Kinuhikari. The nodal position decreased as the seedling density increase at the rate of 0.15 to 0.17 nodes per 10-plant increase per m2. When the tiller emergence from lower nodes was suppressed by deep-water management during establishment and early growth stage, the decrease of the nodal position of the last visible primary tiller with the increase of seedling density was not influenced, but the nodal position increased by 0.6-1.3 nodes compared with that in the normal water management. This phenomenon is attributed to the relative delay of canopy development and competition for resources.
