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Use of growth regulators to control shoot elongation and flower initiation of magnolia

Bożena Matysiak

Research Institute of Pomology and Floriculture
Waryńskiego 14, 96-100 Skierniewice, Poland
e-mail: bmatys@insad.pl

The effects of chlormequat (1000, 2000, or 4000 mg l-1), daminozide (1500, 3000, or 6000 mg l-1), ethephon (250, 500, or 1000 mg l-1), paclobutrazol (50, 100, 200, or 400 mg l-1), prohexadione-Ca (125, 250, or 500 mg l-1) and daminozide (3000 mg l-1) + ethephon (500 mg l-1) on growth and flower bud formation of container grown magnolia were investigated. The highest reduction in plant height was obtained after prohexadione-Ca application at the highest tested concentration (500 mg l-1). Paclobutrazol and prohexadione-Ca were the most effective in stimulation of branching of magnolia shrubs. Application of daminozide at 6000 mg l-1 and paclobutrazol at 100-400 mg l-1 to two-year-old magnolia ‘Alexandrina’ and ‘Susan’ significantly increased the number of flower buds in comparison with untreated plants. Paclobutrazol at 100 mg l-1 resulted in 152% increase in the number of flower buds in ‘Alexandrina’ whereas 100% more flower buds were observed in ‘Susan’ treated with this chemical at the 400 mg l-1 concentration. Daminozide application at 6000 mg l-1 increased the number of flower buds by 100% in both magnolia cultivars. Single application of chlormequat, ethephon, and prohexadione-Ca failed to affect flower bud production in magnolia.

Matysiak B., 2002. Use of growth regulators to control shoot elongation and flower initiation of magnolia. Folia Horticulturae 14/2: 223-233.