THE ROLE OF ENDOGENOUS GIBBERELLIN IN TULIP STEM GROWTH INDUCED BY IAA AND IBA: RELEVANCE TO INHIBITORS OF GIBBERELLIN BIOSYNTHESIS

M. Saniewski, H. Okubo, K. Miyamoto, J. Ueda
In this study, we investigated the function of auxins, indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) together with gibberellin A3 and inhibitors of gibberellin biosynthesis, paclobutrazol, flurprimidol and prohexadione-Ca, on stem growth of tulips, suggesting that stimulatory effect of auxin on the growth of stem is connected with endogenous active gibberellins. IBA applied as a lanolin paste stimulated stem growth of tulips as well as IAA. IAA and IBA promote the growth of lower internodes as well as 4th internode in tulip stem. Inhibitors of gibberellin biosynthesis applied simultaneously with auxins were more effective on inhibition of the growth of lower internodes induced by IAA or IBA than that in 4th internode. GA3 did not recover the inhibitory effect of inhibitors of gibberellin biosynthesis on tulip stem elongation induced by IAA and IBA. Simultaneous application of GA3 with IAA and IBA also did not stimulate IAA- or IBA-induced growth. These results strongly suggest that considerable levels of endogenous active gibberellins substantially contribute to tulip stem growth with endogenous auxins. Differences in susceptibility and/or responsiveness of tulip stems between exogenously applied gibberellins and, auxin and inhibitors of gibberellin biosynthesis are also suggested.
Saniewski, M., Okubo, H., Miyamoto, K. and Ueda, J. (2012). THE ROLE OF ENDOGENOUS GIBBERELLIN IN TULIP STEM GROWTH INDUCED BY IAA AND IBA: RELEVANCE TO INHIBITORS OF GIBBERELLIN BIOSYNTHESIS. Acta Hortic. 932, 397-403
DOI: 10.17660/ActaHortic.2012.932.58
https://doi.org/10.17660/ActaHortic.2012.932.58
paclobutrazol, flurprimidol, prohexadione-Ca, tulip, stem, gibberellins, auxins
English

Acta Horticulturae