Abscission of Flower Peduncles in Rose ( Rosa × hybrida) Plants and Evolution of Ethylene

Abstract

Summary Ethylene evolution from decapitated rose ( Rosa × hybrida cv. Nubia) peduncles in planta and explants showed a climacteric pattern typical of abscising plant organs. The rate of ethylene evolution from nondecapitated explants was higher than that from decapitated ones and was the highest from separated flower buds. Local application of IAA at the site of bud removal postponed abscission of decapitated peduncles by 10 days in comparison with decapitated peduncles without IAA. The inhibition of abscission with IAA was accompanied by an earlier and higher rise in ethylene evolution and by yellowing of the peduncles; basal application of STS (silver thiosulphate) postponed the abscission of decapitated peduncles for a period longer than 6 weeks without any visible symptoms of senescence and was also associated with increased evolution of ethylene. Application of 1-aminocyclopropane-1-carboxylic acid (ACC) stimulated evolution of ethylene and promoted abscission of non-decapitated and decapitated peduncles, as well as of peduncles treated with IAA, but did not affect the STS-imposed inhibition of peduncle abscission. An extremely high rise in ethylene was measured without affecting abscission when STS and IAA treatments were combined. The role of auxin in context of the concept of «tissue sensitivity» to ethylene is discussed. A possible existence of two separate ethylene systems, one involved in regulation of flower bud development and the second in regulation of flower bud and leaf absiccion, is discussed.