Topophysis affects the potential of axillary bud growth, fresh biomass accumulation and specific fresh weight in single-stem roses (Rosa hybrida L)

Topophysis, the effect on growth and differentiation of position of axillary buds along the shoot, was studied by propagating five-leaflet-leaf single-node cuttings which were excised from seven stem positions and grown as single stemmed plants. In Rosa Rosa hybrida 'Korokis' Kiss(R), 'Tanettahn' Manhattan Blue(R), and 'Sweet Promise' Sonia(R) following release of the buds from apical dominance by excision, morphogenetic development was studied until anthesis. The time from excision/planting until onset of bud growth, visible flower bud appearance, and anthesis was generally shorter in plants originating from apical bud positions than From basipetal positions. Topophysis mainly affected the onset of axillary bud growth; the earliest growth and development was found in cuttings from the second uppermost node position. This node tended to have the lowest plastochron value, which indicated the existence of a transition between sylleptic and proleptic buds. Stern length at visible flower bud and al anthesis generally increased as the cutting position changed basipetally until the second lowest position, and the number of five-leaflet-leaves at anthesis and the total number of nodes generally increased basipetally. For internode length, growth rate, and fresh biomass efficiency the cuttings taken from the uppermost and lowermost positions generally had significantly lower values than cuttings from all medial positions., At anthesis, plants originating from cuttings excised from lower medial positions generally had a higher fresh weight, greater flower stem diameter, and a significantly higher specific fresh weight than those plants originating from apical or basal positions. Among the cultivars, Sonia was the most efficient in increasing fresh biomass and had the highest growth rate, whereas Manhattan Blue possessed the highest specific fresh weight, indicating a higher plant quality. It is suggested that topophysis in Rosa is an independent phenomenon intrinsic to the axillary bud. (C) 1996 Annals of Botany Company