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Jong-Seok Park and Kenji Kurata

effect of microbubbles on the growth of leaf lettuce in a deep flow technique (DFT) hydroponics culture system. To understand the effects of microbubbles on plant growth, we compared lettuce treated with macrobubbles generated by aquarium aeration stones

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Kellie J. Walters and Christopher J. Currey

number, height, leaf index, internode length, and branch number for 35 basil cultivars grown in either a nutrient film technique or deep flow technique hydroponic system in a greenhouse. Data were collected 4 weeks after transplanting seedlings into

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Samuel Doty, Ryan W. Dickson, and Michael Evans

Ornamental bedding plant operations transitioning to leafy greens and herb production must decide whether to invest in new hydroponic equipment or modify existing culture systems for edible crops. In addition, common practices used to increase space-use and production efficiencies during bedding plant production may be modified for hydroponic leafy greens and herbs, such as purchasing large seedlings for transplant. The objective of the first experiment was to evaluate plant growth in a modified and novel shallow aggregate ebb-and-flood (SAEF) system intended for bedding plant growers with an emphasis on comparing yield across four basil (Ocimum basilicum) cultivars grown in the SAEF system to those grown using the traditional nutrient film technique (NFT) and deep water culture (DWC) hydroponic systems. The second experiment objective was to evaluate basil seedling size and the time of transplant to NFT hydroponic systems to determine effects on the final yield. ‘Genovese’ basil seedlings were grown in trays with cell counts of 32, 50, 72, 105, and 162 cells with corresponding root volumes per plant of 98.1, 50.2, 38.5, 19.6, and 16.3 cm3, respectively. Seedlings were transplanted to NFT systems at 14, 21, and 28 days after sowing and were harvested at 35 days. In the first experiment, overall basil shoot fresh and dry weights per plant were intermediate in the SAEF system (90.4 and 8.3 g) compared with the DWC (102.6 and 9.1 g) and NFT (75.8 and 6.6 g) hydroponic systems. In the second experiment, final shoot fresh and dry weight per plant increased as seedling root volume increased from 16.3 cm3 [72.8 and 5.5 g (162-cell tray)] to 98.1 cm3 [148.5 and 12.2 g (32-cell tray)]. Transplanting seedlings at later dates decreased yield across tray size and root volume treatments. Differences in yield between culture systems may have resulted from differences in nutrient supply and availability for plant uptake. Transplant of large seedling plugs to hydroponic culture was not shown to increase space-use efficiency after transplant without compromising yield, likely because root zone factors limited growth during seedling production. Further investigation into maximizing plant growth during seedling production and evaluating the effects of seedling size and transplant practices are needed to determine the potential for increasing space-use and production efficiencies.

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Eun Young Yang*, Jung-Sim Oh, and Yong-Beom Lee

This experiment was carried out to observe the effect of mineral nutrient control in photosynthetic capacity of single-node cutting rose grown in a closed hydroponic system. Single-node cutting rose `Versillia' was grown in aeroponics and DFT system and was irrigated with the nutrient solution of the Univ. of Seoul (NO3 -N 8.8, NH4 -N 0.67, P 2.0, K 4.8, Ca 4.0, Mg 2.0 me·L-1). Recirculated nutrient solution was managed by five different control method: macro- and micro-element control in aeroponic system (M&M); macro-element control in aeroponic system (M); nutrient solution supplement in aeroponic system (S); electrical conductivity (EC) control in aeroponic system (EC-A); EC control in deep flow technique system (EC-D). The photosynthetic rate, stomatal conductance and transpiration rate at 35 days after transplant with M&M and M were higher compared to those with S, EC-A and EC-D. The maximal efficiency of photochemistry (Fv/Fm) was higher for M&M, M and S than that with EC-A and EC-D. Therefore, it is possible to increase photosynthetic capacity of rose with mineral nutrient control in recirculated nutrient solution.

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Joo Hyun Lee, Yong-Beom Lee, and Kyu Sook Lee

Wasabi japonica plantlets were acclimatized in a hydroponic system to determine effective procedures. The plantlets were cultured on solid Murashige-Skoog medium with 3% sucrose. Shoots that formed roots were transplanted into hydroponic systems: 1) acclimatization in ebb-and-flow (EBB) for subirrigation (medium: granulated rockwool and coir); and 2) acclimatization in deep flow technique (DFT). The plantlets were acclimatized for 5 weeks under two irradiance treatments, 50 and 300 mmol·m-2·s-1. Photosynthetic capacity in high PPF was higher than that in low PPF during acclimatization. Electron transport rate from PS II (ETR) and biomass production increased significantly with increased light availability. The fresh weight, dry weight, and leaf area of plantlets in high PPF were higher than those in low PPF. In particular, the dry weight and ETR of the plantlets grown in high PPF increased more than twice as much as those in low PPF. At 50 mmol·m-2·s-1 PPF, growth indexes, such as number of leaves, leaf length, leaf width, leaf area, fresh weight, and dry weight, were higher in EBB (granulated rockwool) > EBB (coir culture) > DFT. At 300 mmol·m-2·s-1 PPF, those indexes were higher in DFT > EBB (granulated rockwool) > EBB (coir). The Wasabi japonica plantlets acclimatized in a hydroponic system also had a superior performance when they were transferred to the field.

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Eun Young Yang*, Hye Jin Lee, and Yong-Beom Lee

The application of a closed hydroponic system for rose poses some horticultural problems. The nutrient uptake by the plants changes constantly depending upon environmental conditions and growing stages, which results in the imbalanced composition of the drained solution and aggravates root environmental conditions. This research was aimed to observe the effect of mineral nutrient control method on the nutrient solution management in a closed hydroponic system. Single-node cutting rose `Versillia' was grown in aeroponics and DFT system and was irrigated with the nutrient solution of the Univ. of Seoul (NO3 -N 8.8, NH4 -N 0.67, P 2.0, K 4.8, Ca 4.0, and Mg 2.0 me·L-1). Recirculated nutrient solution was managed by five different control method: macro- and micro-element control in aeroponic system (M&M); macroelement control in aeroponic system (M); nutrient solution supplement in aeroponic system (S); electrical conductivity (EC) control in aeroponic system (EC-A); EC control in deep flow technique system (EC-D). In the EC control method, the concentration of NO3 -N exceeds optimal range whereas P and Mg decreased at the later stage of plant growth. The overall mineral nutrient content increased with S. On the other hand, the nutrient content of root environment was maintained optimally with M&M and M.

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Eun Young Yang*, Keum Soon Park, Dong Soo Lee, and Yong-Beom Lee

This study was conducted to understand the effect of different nutrient control method on the growth, cut-flower quality, root activity and fertilizer consumption. Single-node cutting rose `Versillia' was grown in aeroponics and DFT system and was irrigated with the nutrient solution of the Univ. of Seoul (NO3 -N 8.8, NH4 -N 0.67, P 2.0, K 4.8, Ca 4.0, Mg 2.0 me·L-1). Recirculated nutrient solution was managed by five different control method: macro- and micro-element control in aeroponic system (M&M); macroelement control in aeroponic system (M); nutrient solution supplement in aeroponic system (S); electrical conductivity (EC) control in aeroponic system (EC-A); EC control in deep flow technique system (EC-D). The mineral nutrient control method had significantly effected on the cut-flower quality. In the M&M and M, flower length, fresh weight and root activity were higher than those with other mineral nutrients control method. Although EC-A and EC-D could save total amount of fertilizer compared to M&M and M, the growth and quality of the rose with EC control system were lower than those with mineral nutrient control system. Therefore, these result suggest that EC control system is not economic method in a closed hydroponic system.

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Xuan-Chun Piao, Debasis Chakrabarty, Eun-Joo Hahn, and Kee-Yoeup Paek

In vitro nodal cuttings of potato (Solanum tuberosum L.) `Atlantic' and `Russet Burbank' from bioreactor culture were hydroponically cultured for 28 days using a deep flow technique (DFT) system. The response of plant growth and photosynthesis to different levels of solution electrical conductivity (EC; 0.08, 0.15, 0.22 and 0.36 S·cm-1) and pH (3, 4, 5, 6 and 7) were studied. The best growth, characters of shoot length, total shoot and root fresh and dry weight, were obtained in nutrient solution of pH 6.0 and EC 0.15 S·cm-1 for `Atlantic', while pH 7.0 and EC 0.15 S·cm-1 were found to be best for `Russet Burbank'. Plantlet growth was reduced by low solution pH (3.0) and high EC level (0.36 S·cm-1). Photosynthetic rate, stomatal conductance, and transpiration rate were also found to be affected by EC levels. Down regulation of photosynthesis, as indicated by chlorophyll fluorescence results, were observed when potato plantlets were cultured under nutrient solution of higher EC level. Plantlet growth and photosynthetic rate increased as photosynthetic photon flux (PPF) levels increased from 50 to 250 μmol·m-2·s-1. Particularly, increasing PPF level had a more distinctive effect on plantlet growth than CO2 enrichment condition. It was apparent from this study that nutrient solution of pH 6.0 and 0.15 S·cm-1 EC in combination with high PPF level (250 μmol·m-2·s-1) were suitable for hydroponic culture of potato plantlets as it would maximize net photosynthetic rate, and achieve the highest growth rates.

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. Walters and Currey (p. 645) grew 35 basil varieties in two different hydroponic systems, nutrient film technique and deep flow technique. Although hydroponic system had little effect on growth, the varieties differed widely in fresh and dry weight, height

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Alexander G. Litvin, Christopher J. Currey, and Lester A. Wilson

deep-flow technique (DFT) hydroponic units. Nutrient solution was contained by a plastic open tank measuring 15 × 91 × 182 cm (height × width × length), with a 227-L capacity (Active Aqua; Hydrofarm, Petaluma, CA). Initial nutrient solutions were