Ethylene production, ACC and MACC content of freesia buds and florets.

Changes in ethylene production, ACC (1-aminocyclopropane-1-carboxylic acid) and MACC (1-(malonylamino)-cyclopropane-1-carboxylic acid) content of buds and florets of detached inflorescences were studied. Most of the ethylene produced by the inflorescences came from small buds at the apex. This increase in ethylene production coincided with an increase in ACC and MACC content. Between days 4 and 5, both ethylene production and ACC content decreased markedly while MACC was still increasing. About 95% of the ACC found in buds came from the anthers. The surge in ethylene production was followed by death of the buds. It is concluded that detachment of inflorescences leads to a stress situation for the small buds at the apex of the inflorescence where ethylene biosynthesis is stimulated.