Abstract: We used the cut flowers of Freesia hybrida ‘Shangnong jinhuanghou’ to study the endogenous hormone content changes of petals in the process of flowering and aging during vase holding in distilled water. We determined the contents of auxin(IAA), gibberellic acid(GA), zeatin nucleoside(ZR) and abscisic acid(ABA) by enzyme-linked immunoassay, while measured ethylene releasing rate by gas chromatography, and observed the content changes of five endogenous hormones in petals during vase holding. The contents of endogenous ZR decreased constantly, and the lowest content decreased by 83.8% on the 10th day compared to that at beginning. The change trend of endogenous GA is similar to ZR content, the lowest content of GA was present on the 10th day, correspond to 3.8% by compared with that at beginning. However, the content of endogenous ABA, accumulating after a descend, dropped to the lowest level on the fourth day, equivalent to 52.4% of the content at beginning. Endogenous IAA content, showing a trend of decline after rising first, emerged a peak on the second day, and down to a minimum level on the 10th day, equivalent to 12.2% of the highest. At the same vase period, contents of the endogenous IAA, ZR and ABA had no significant difference in the different positions of inflorescence, but endogenous GA content in the upper floret of inflorescence is significantly higher than the base and mid in the first four days during vase holding. Change of ethylene releasing rate increased followed a constant decrease up to the end of vase holding. However, the ethylene releasing peak of mid position floret appeared on the second day, while the upper floret on the fourth day. The metabolic unbalance of endogenous hormone levels might be one of the causal factors of freesia flower senescence.

Key words: Freesia hybrid, vase holding, petals aging, endogenous hormone