Abstract
In rice plants, the leaf number of the main stem is used to express the plant age. But there was no way to express the age of the individual tiller. We used the concept of plant age indicated by leaf number to estimate the age of the individual tillers. The age of individual tillers expressed by leaf number is the number of spread leaves plus the ratio of the length of the emerged part of the leaf-blade. To compare the ages of every tiller with each other, we prescribed a relative tiller age (RA) to the individual tillers. Using these indicators, we could compare the growth of tillers with that of the main stem. Plants of three rice cultivars were in pots (1 plant/pot) under irrigated conditions, and the position of each leaf was marked. The leaf emergence rate of early developed tillers changed simultaneously with that of the main stem. During the late vegetative stage, the leaves of higher leaf position on tiller emerged at the higher order of tillers. The differences (D) in RA between tillers and the main stem increased with the plants' growth, and peaked just before the flag leaf emergence. The tillers of higher order showed a larger D, and there was a varietal difference in the value of D.
