The Morphogenesis of Regeneration Buds in Hordeum bulbosum L.—A Perennial Grass

The tillering phase in Hordeum bulbosum L. is terminated when the newly-formed axillary buds no longer emerge as tillers, but differentiate into dormant regeneration buds. The pattern of development of the axillary buds differs during the tillering phase and the post-tillering phase. During the former, accumulation of leaf primordia corresponds to the age of the bud, i.e., leaf number per bud increases basipetally along the shoot. During the post-tillering phase, leaf number per bud decreases basipetally from the base of the future bulb internode. This transition is brought about by an acceleration in the rate of accumulation of leaf primordia which is more sustained in the buds situated closer to the base of the bulb internode. These positional differences in the morphogenesis of the regeneration buds are reflected in their physiological responses during the relaxation of dormancy and activation of the buds.