Factors intrinsic to the axillary bud determine topophysic effects on bud and shoot growth and flower development in Rosa hybrida

Topophysis (the influence of the position of axillary buds along the shoot on bud and shoot growth, fresh biomass accumulation, and flower development) were studied in Rosa hybrida L. Single-node cuttings with five-leaflet leaves were excised from nine stem positions and grown as single-stemmed rose plants. Plants were grown at 20-h photoperiods, 22 degrees C average air temperature, and an average photosynthetic photon flux density of 228 mu mol m(-2) s(-1). Generally onset of axillary bud growth and initial shoot growth were promoted, and flower height and bloom quality were reduced in plants from apical bud positions. Stem diameter, stem growth rate, and biomass buildup were greatest from medial bud positions; the plastochron was greater, and stems and internodes were longer, from basal bud positions. Flower diameter and cut newer vase life were not significantly influenced by topophysis. The results demonstrate that topophysis can determine the potential for plant development and flowering in R. hybrida and that this knowledge may be used to regulate plant growth. Results also indicate intrinsic mechanisms determining axillary bud growth, but the physiology of topophysis is presently unclear. A probable role of cytokinins in the topophysic prevention of growth observed is discussed.