Abstract
To clarify the characteristics of rice growth, number of leaves, number of tillers and stem weight, the developmental stage estimation method (DVI method) using air temperature was applied to rice growth planted under different number of seedlings per hill conditions for the rice variety Koshihikari. The curve line models were well suited for comparison of the DVI values and the number of leaves in the different seedling groups. The number of leaves was higher at hills with a few seedlings than that of hills with many seedlings. In the main stem flag leaf number, there was a 1.5 leaf difference between 1-seedling hills and 8-seedling hills. The three-dimentional curve line models were well suited for comparison of the DVI values and the number of tillers per hill for each seedling groups. The number of tillers was higher in the hills with many seedlings than the hills with a few seedlings at every developmental stage. Both the estimated emergence stage of the last tiller and the maximum tiller number stage appeared faster in the hills with many seedlings than in the hills with a few seedlings. The maximum tiller number stages of 1-seedling and 2-seedling hills followed the panicle formation stages. A high correlation coefficient between stem weight and the number of spikelets per panicle was discovered at each developmental stage. However, it was necessary to consider the tillering dimension before the panicle formation stage. The growth curves were well suited for comparison of the DVIvralues and the stem weights of the main stem and the 4th node tiller for each seedling number per hill. The dry weight of stems decreased as the seedling number per hill increased. The growth curves were well suited for comparison of the DVIvalues and the stem weights for each number of spiklets per panicle. The dry weight of the stems decreased with the number of spiklets per panicle.
