• FLOWER RESEARCH JOURNAL
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• v.19 no.2
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• pp.81-88
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• 2011

Effect of concentrations of different plant growth retardants (PGRs) supplied to a recirculated nutrient solution in an ebb and flow system on the growth and development of potted Spathiphyllum 'Top-Pin' and 'Mini' was examined. Plants were planted in 10 cm diameter plastic pots filled with a mixture of peat moss and perlite (1 : 1, v/v) on 30 June 2005 and grown until 23 Sep. 2005. In a closed ebb and flow system, 50, 200, 350, $500mg{\cdot}L^{-1}$ daminozide (B-9), 10, 40, 70, $100mg{\cdot}L^{-1}$ paclobutrazol (Boundy), 5, 15, 25, $35mg{\cdot}L^{-1}$ ethephon (Florel), and 1, 4, 7, $10mg{\cdot}L^{-1}$ uniconazole (Sumagic) were supplemented to a nutrient solution at the initiation of experiment. On every irrigation, the nutrient solution containing PGRs was supplied at a 2 cm depth and kept for 15-20 minutes. The surplus nutrient solution was drained back into the tank for next irrigations. Paclobutrazol gave the most pronounced effect in inhibition of stretchiness. The greatest reduction of leaf length, fresh and dry weights of shoot, and elevated chlorophyll content were recorded in Spathiphyllum, with increasing paclobutrazol concentration. Daminozide concentration greater than $200mg{\cdot}L^{-1}$ resulted in minor stunting. The lowest concentration ($1mg{\cdot}L^{-1}$) of uniconazole showed greater leaf length, leaf width, and leaf petiole length than the control ($0mg{\cdot}L^{-1}$). Uniconazole concentration greater than $1mg{\cdot}L^{-1}$ resulted in similar plant growth as the plant in the control ($0mg{\cdot}L^{-1}$). High concentration ($35mg{\cdot}L^{-1}$) of ethephon resulted in the shortest leaf length, and the greatest chlorophyll content. Inhibition of stretchiness was observed even in the lowest concentration treatments. Among the PGRs, paclobutrazol was most effective in suppressing plant stretchiness. In both cultivars, ethephon and paclobutrazol, but not daminozide and uniconazole, significantly inhibited stretchiness. The results suggested that plant growth retardants (ethephon or paclobutrazol) selected in this study may be used as the most effective agents for inhibition of stretchiness in Spathiphyllum.

• FLOWER RESEARCH JOURNAL
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• v.16 no.4
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• pp.260-265
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• 2008

Studies were carried out to elucidate the effect of temperature, glasshouse forcing date and $GA_3$ on the growth and flowering of pot Hydrangea macrophylla Ser. The plant height was elongated in the $5^{\circ}C$ treatments as 38 cm compared with $20^{\circ}C$ treatment as 6.7 cm, and stem length showed the similar results. The leaf length and width was broadened in the lower temperature, and stem diameter showed the same tendency. The first flowering date in the $15^{\circ}C$ and $20^{\circ}C$ treatment shortened markedly than $5^{\circ}C$ treatment. Days to flowering date of $5^{\circ}C$ was 161 day, while it shortened as 88 day in the $15^{\circ}C$ treatment. The flowering rate was 75.8~90.7% in the temperature. The plant height was elongated in the late glasshouse forcing date, and the leaf length and width showed the similar tendency. The plant height increased in the higher concentration of $GA_3$ compared to the control, and leaf length and width showed the similar results. The first flowering day was advanced by 7 days in the $GA_3$ $50mg{\cdot}L^{-1}$ treatment which had been transferred to greenhouse on Dec. 30 compared with the control of which first flowering day was March 17, and the days to first flowering was conspicuously shortened in the late glasshouse forcing treatment. The width of flower cluster was increased in the $GA_3$ at Dec. 30 glasshouse forcing treatment. The flowering rate was markedly decreased as 62.3% in the control of Nov. 15 treatment, but was increased as 97.9% of $GA_3$ $50mg{\cdot}L^{-1}$ of Jan. 15 treatment.