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  • Author or Editor: Seung Won Kang x
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The influence of water-soluble fertilizer (WSF, 3 different formulations) and slow-release fertilizer (SRF, Osmocote, 14N-6.2P-11.6K) on the growth and quality of potted carnation (Dianthus caryophyllus cv. Invitation) in a C-channel mat irrigation system was investigated. When fertilized with 0.4, 0.8, or 2.0 g·L-1 of WSF (20N-7.9P-16.6K for weeks 1-4, 13K-0.1P-18.8K for weeks 5-11, and 15N-0P-12.5K for weeks 12-15), the 0.8 g·L-1 solution produced the highest quality plants as determined by total shoot fresh and dry weights, leaf area and number, plant height, and number of branches per pot. The quality of plants grown with 0.4 g·L-1 or 2.0 g·L-1 WSF solution was also commercially acceptable. The growth rate of all plants began to accelerate at around 60 days after treatment started, with some variation with the fertilizer treatments. Plants began to show a reduced growth rate at around 90 days from the treatment when they underwent a phase change from vegetative growth to reproductive growth. Plants grown with SRF alone were less vigorous than those grown with WSF, especially when temperature was lower. Results of this study indicate that high quality pot carnations can be produced, using a reduced amount of fertilizer applied to the C-channel mat irrigation system.

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Efficacy of application methods and concentration of plant growth retardants on growth of chrysanthemum (Dendranthema ×grandiflorum cv. Cheasepeake) was tested. B-9 or cycocel (CCC) as a growth retardant was applied as drench or subapplication with nutrient solution. In the case of B-9 drench treatments, as B-9 concentrations increased, numbers of flowers and flower buds increased except in the 1500-ppm treatment. Increasing concentration of CCC also resulted in reduction of flower numbers, total plant height, total leaf area, branch number, and fresh weight. Reduction ratio of total plant height in 2000 ppm showed about 56.9% being compared to that of the 100-ppm drench treatment. B-9 or CCC, combined with nutrient solution, was also supplied from the C-channel subirrigation system. The B-9 subapplication treatment showed no significance among these concentrations, but flower numbers, total plant height, average plant height, and leaf numbers decreased as concentrations of CCC increased. B-9 or CCC with the same concentration was drenched after 2 weeks of the first experiment to compare planting time efficacy. Measured data increased until B-9 increased up to 2500 ppm and severe growth retardation resulted from the 5000-ppm treatment. Through this growth retardant application study, the combination of drenching concentration and period of plant growth regulators (PGRs) may result in effective growth retardation and reduction of application concentrations for pot plant production.

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Variegated foliage plants are often used in interiorscaping in low light environments. The changes in leaf morphology and coloration of two variegated foliage plants, english ivy (Hedera helix ‘Golden Ingot’) and polka dot plant (Hypoestes phyllostachya), under various light intensities [photosynthetic photon flux (PPF) at 2.7, 6.75, 13.5, 67.5, and 135 μmol·m−2·s−1] were investigated to elucidate their optimum indoor light environment. Digital image analysis was used to quantify the changes in variegation area and color in CIELAB color space. The changes in leaf morphology (thickness, length:width) and coloration were different between the two species. In general, growth of both species increased with increasing PPF. English ivy showed no significant changes in leaf variegation under different PPF. Under low PPF (≤13.5 μmol·m−2·s−1), newly developed leaves of polka dot plant had reduced leaf variegation (44%, 72%, and 85% variegation loss under 13.5, 6.75, and 2.7 μmol·m−2·s−1, respectively). Anthocyanin content in leaves of polka dot plant also decreased with decreasing PPF, which reduced plants’ aesthetic quality. English ivy leaves under high PPF (≥67.5 μmol·m−2·s−1) displayed high brightness (L*) and yellowish green color (hue angle < 108°), which diminished its aesthetic value. Smaller leaf size and narrower shape of polka dot plant leaves under high PPF (≥67.5 μmol·m−2·s−1) also diminished its aesthetic value. Overall, english ivy performed well in a PPF range from 2.7 to 13.5 μmol·m−2·s−1, and polka dot plant required a PPF of at least 13.5 μmol·m−2·s−1 to maintain its red-purple variegation in the indoor environment.

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