Abstract
A current understanding that the beginning of internode elongation of rice plants coincides with the time of panicle initiation is not always true. This is owing to the fact that when rice varieties of wide scope and their hybrid populations are dealt with the panicle initiation does neither necessarily coincide with nor precede the internode elongation. Thus it is inferred that the internode elongation makes its start by two kinds of stimuli ; one is connected with the trigger mechanism of the panicle initiation and the other one has something to do with a comming of paticular leaf stage.
