Growth control of kalanchoe cultivars Rako and Gold Strike by application of paclobutrazol and uniconazole as soaking treatment of cuttings

This study was conducted to test the potential of paclobutrazol and uniconazole used at the propagation stage as a plant growth retardant (PGR) of kalanchoe cultivars Rako and Gold Strike. Three node terminal cuttings were soaked in 500 mL of 0.05, 0.25, or 0.50 mg·L-1 paclobutrazol or uniconazole solution for 2 h. After soaking treatment, the cuttings were rooted in a fog tunnel with mean daily air temperature of 18.2°C and RH of 66%. Three replicates per treatment and eight plants per each replicate were used. All cuttings rooted well in all treatments. At all applied concentrations, plant height and stem internode length decreased significantly in both cultivars. Uniconazole was more effective than paclobutrazol at similar concentrations in suppressing stem growth. Both PGRs affected the number of leaves when compared with the control. Leaf area was significantly changed by different cultivars and PGR types, but not by the concentrations of PGR. While leaf chlorophyll concentration increased with an increase in the concentration of PGRs. The number of florets was increased in all PGR treatments when compared with the control. Consequently, soaking cuttings in PGR solutions seems to have a potential to reduce stem elongation of kalanchoe. This method of PGR treatment could become an environmentally friendly method in commercial productions, because of low PGR concentration needed and controlled application.

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