Promotion of Globularia sarcophylla flowering by Uniconazol, an inhibitor of gibberellin biosynthesis

Ehud Katz, Ofra Ziv, Ramaswamy Venkatachalam, Eitan Shlomo, Abraham H. Halevy, David Weiss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut flower in Israel. Two major problems have prevented its commercialization: the late-summer blooming and the low quality of its flowering shoots. In the present work we studied the factors affecting G. sarcophylla flowering. We found that long-day (LD) conditions slightly promote flowering but artificial photoperiodic illumination does not enable the manipulation of flowering time. On the other hand, treatment with the gibberellin (GA)-biosynthesis inhibitor, Uniconazol, had a dramatic promotive effect on flowering time. Application of Uniconazol in autumn or winter induced flowering in winter or early spring, respectively. The inhibitor did not advance flowering during the summer or in the phytotron under high temperatures. When plants were grown in the spring/summer under heavy shading, they did not flower unless they were treated with Uniconazol. Uniconazol treatment also improved flower quality by reducing the length of inflorescence pedicles. This effect was found in all seasons. Based on our results, we raise the hypothesis that Uniconazol treatment induces flowering by diverting assimilates to the apex. Inhibition of GA biosynthesis under conditions limiting photosynthetic activity reduces vegetative growth and increases the availability of assimilates to the apex, leading to flower initiation. However, under high irradiance and/or high temperatures, when the levels of assimilates are sufficient to induce natural flowering, the inhibitor has no further effect.

Original languageAmerican English
Pages (from-to)423-431
Number of pages9
JournalScientia Horticulturae
Volume98
Issue number4
DOIs
StatePublished - 29 Sep 2003

Bibliographical note

Funding Information:
This research was supported by the Israeli Ministry of Agriculture and by the Association of Israeli Flower Growers. This work was supported also by the Pearlstein Fund for research in floriculture at the Hebrew University, and we thank the donors for their help.

Keywords

  • Day length
  • Flowering control
  • Gibberellin
  • Globularia sarcophylla
  • Uniconazol

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