Resumo

FLOREZ, Víctor Julio  e  PEREIRA, Maria de Fátima D. Aleixo. Opposite concentrations of IAA-ABA increase flower development in Solidago x luteus. Agron. colomb. [online]. 2008, vol.26, n.2, pp.237-245. ISSN 0120-9965.

The floral development consists of many sequential steps, each one with specific requirements affected directly by the chemical and environmental conditions. The light plays a central role in the initiation of floral development. In Solidago x luteus (M. L. Greene) Brouillet & Semple (= x Solidaster hybridus, x S. luteus), the response are given to the long days (LD) for floral induction and those to the short days (SD) for flower development. Samples of leaves and floral buds of S. x luteus plants grown under different photoperiodic conditions (SD (8 h) and LD (18 h)) were collected. Performing different bioassays allowed detecting both promotory and inhibitory activity of substances present in the acid phase of the extracts. Further more, the concentrations of IAA and ABA presented in the extracts were determined through High Performance Liquid Chromatography. In any treatment, the activity of gibberellin-like substances was not detected. In LD (18 h) plants, it was observed a higher concentration of IAA in leaves and floral buds than that in SD (8 h) plants suggesting that it may be related to more rapid anthesis in plants kept in short days. In extracts from leaves and flower buds in SD plants, the higher levels of ABA were found in relation to the beginning of the photoperiodic treatments. Therefore, in the balance of IAA:ABA, they seem to exist in opposite concentrations, mainly in the flower buds under 8 h, where the higher amount of ABA and absence of IAA were observed.

Palavras-chave : Solidaster; gibberellins; indole-3-acetic acid; abscisic acid; HPLC.

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