OCCURRENCE OF SPONTANEOUS SHOOT REGENERATION ON LEAF STIPULES IN RELATION TO HYPERFLOWERING RESPONSE IN MICROPROPAGATED STRAWBERRY PLANTLETS

Stipular bud (SB) formation occurred spontaneously on ''Gorella'' stra wberry leaf stipules during proliferation phase on Boxus medium. These buds gave rise to normal shoots on the inner median zone between the stipule tips. Some stipular buds also have been observed on other part s of adaxial surface of the stipule. Stipular bud formation took place directly on the stipule without an intel mediate callus. The first st age consisted of subspherical protrusions of small cells which progres sively differentiated into shoots that were able to proliferate and to root. Scanning electron microscopy was used to examine the developmen tal stages of this adventitious organogenesis and to describe morpholo gic abnormalities, e.g., multiapex formation and fasciation. In vitro cloning of plantlets was made from axillary and SBs produced by the sa me tufts. The greater flowering abundance of stipular plants resulted in a drastic reduction of the commercial production and the fruit cali ber when compared to axillary plants. However, the general phenotype o f the mother cultivar (Gorella) was not affected in either case.