Alteration of endogenous cytokinins in axillary buds of conventionally grown greenhouse rose plants

Abstract Content and structure of cytokinins were measured in axillary buds along shoots of rose plants ( Rosa hybrida cv. Texas). Three different shoot sections could be distinguished beneath the flower peduncle. The upper section with tri- and monofoliate leaves is characterized by lateral shoots from non-inhibited buds growing concomitantly with the growth of terminal flower. The second section from the top is characterized by leaves with five or more leaflets. The third section is characterized by few five-leaflet leaves followed downward by less developed leaves. Isopentenyl cytokinins were the main cytokinins in axillary buds of three-leaflet leaves in the uppermost section and in the buds of the upper five-leaflet leaves in the second section of non-decapitated shoots. Zeatin and zeatin riboside were the main cytokinins in the lowest buds in axils of five-leaflet leaves of the third section. Three days after decapitation of the shoots above the uppermost five-leaflet leaf (80–90 cm long stems) or above the lowest five-leaflet leaf (10–15 cm long stems) a relatively very high content of zeatin and zeatin riboside was present in the uppermost remaining axillary buds. On the other hand, 1 week after decapitation the isopentenyl cytokinins were the main cytokinins in the two top axillary buds on the long shoots. The role of isopentenyl cytokinins in ready to sprout, to grow and to flower axillary buds as well as accumulation of root synthesized cytokinins in the lowest buds are discussed.