African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6728

Full Length Research Paper

Endogenous gibberellin levels during early fruit development of macadamia

Stephen J. Trueman
Faculty of Science, Health and Education, University of the Sunshine Coast, Maroochydore DC 4558, Australia.
Email: [email protected]

  •  Accepted: 12 August 2011
  •  Published: 26 September 2011


Gibberellins play a key role in flower and fruit development, and fruits often contain high gibberellin concentrations. This study quantified endogenous gibberellins in flowers and immature fruits of the macadamia cultivars, H2 and 246, to assist in developing growth-regulator treatments for improving fruit set. GA1, GA3, GA8, GA9 and GA20 was detected in flowers or fruits of both cultivars, and GA4were detected in flowers of cultivar 246. The timing of gibberellin accumulation was consistent between cultivars but total concentrations were very low (< 7 pmol g-1 fresh weight). Low gibberellin levels are consistent with the inability of the gibberellin-synthesis inhibitor, paclobutrazol, to influence fruit retention in macadamia.


Key words: Abscission, fruit drop, kernel, nut, paclobutrazol, plant growth regulators, Proteaceae.