Abstract
1) This study was carried out to make clear the distribution of morphological abnor- mal spikelts induced by gibberellin. 2) It was indicated that the number of spikelets was increased remarkably with the treatment as previously reported and the increase was more conspicuous in upper primary branches than in lower ones. 3) Main morphological abnormalities, such as inception of additional glumes, chandes of stamens and pistils in number were found more frequently in the upper portion of the primary branches. 4) Judging from the above results, it is considered the morphogenic effects of gibberellin on panicle development are more remarkable in the upper or distal portion of panicles or primary branches. This tendency also supported by the writers' studies on the effects of gibberellin on the vascular development in panicles. 5) On the other hand, so called "white hulls" were found frequently in the basal portion of lower primary branches. So, it is concluded that the initiation of "white hulls" should be brought about by a quite different pathway from that of the morphogenic abnormalities. 6) The difference in frequency of the abnormality in glume, stamen and pistil was indicated and discussed from the stand-point of the ontogenic changes in form and related morphogenic substances in the meristematic tissue of spikelet primordium.
