Changes in hormone concentrations in leaf, node, shoot tip, and fruit samples of three Turkish olive (Olea europaea L.) cultivars (`Gemlik', `Memecik', and `Tavsan Yuregi') were monitored at monthly intervals over two successive years of the alternate-bearing cycle. Concentrations of abscisic acid (ABA), indole acetic acid (IAA), gibberellic acid-like substances (GA), and kinetin-like cytokinin were determined and their relationship to flower bud formation were examined during “on” and “off” years. Results showed significant differences in IAA, ABA, GA3-like, and kinetin-like cytokinins between “on” and “off” cropping years in various tissues of olive trees. Relative balances between GA3-like and ABA concentrations of tissues appears to exhibit evidence of being a key regulator of floral development and alternate bearing.

The effects of method of application and dose of paclobutrazol on the growth and flowering characteristics of Lupinus varius L. were studied. On 17 Dec., seeds were sown into 18-cm pots (three seeds per pot) filled with a mixture consisting of 2 peat: 1 river sand (by volume). On 25 Mar., when 5% of the plants had elongated first internodes, doses of paclobutrazol at 0 (control), 0.625, 1.250, and 2.500 mg a.i./plant were applied to plants as a foliar spray or media drench. The application of paclobutrazol led to a slight shortening of the time to flowering, especially when applied as a foliar spray. Plant height and internode length, length, and internode length of the main inflorescence significantly decreased with increased doses of paclobutrazol and this also happened with the number of branches per plant, branch length, and length and internode length of branch inflorescence. On the contrary, stem, main, and branch inflorescence diameters significantly increased with increased doses of paclobutrazol, whether applied as a foliar spray or media drench. However, drench applications of paclobutrazol were consistently more effective than foliar spray treatments on most of the growth characteristics investigated. Paclobutrazol, in particular when applied as a foliar spray, also increased the number of flowers on main and branch inflorescences relative to the control, but media drenched applications of paclobutrazol at doses of 1.250 and 2.500 mg a.i./plant resulted in consistent significant reductions in the number of flowers on branch inflorescences. Chemical name used: (±)-(R*,R*)-β[(4-chlorophenyl)methyl]-α-(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

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