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Chieri Kubota and Toyoki Kozai

Growth and net photosynthetic rate of potato (Solanum tuberosum L.) `Benimaru' plantlet in vitro were studied under a conventional photomixotrophic condition [with 20 g sucrose/liter in the medium and under 70 μmol·m-2·s-1 photosynthetic photon flux (PPF)] with minimal ventilation (MV) and under photoautotrophic conditions (without sugar in the medium and under 190 μmol·m-2·s-l PPF) with enhanced natural ventilation using an air diffusive filter (DV) or with forced ventilation (FV). Fresh weight of the plantlets cultured in the FV and DV treatments was 2.4 times that of the plantlets cultured in the MV treatment. Net photosynthetic rate and dry weight per plantlet were the highest in FV followed by DV. For photoautotrophic micropropagation, FV was superior to DV.

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N.C. Yorio, C.L. Mackowiak, B.V. Peterson and R.M. Wheeler

In vitro growth of white potato (Solanum tuberosum L.) cv. Norland was investigated comparing two types of culture vessel enclosures. Nodal cuttings were aseptically transferred to 25 × 150 mm glass culture vessels containing a solidified medium consisting of Murashige and Skoog salts, 1% sucrose, and pH adjusted to 5.8. The vessels were capped with loose-fitted (1 cm gap between the top of the vessel and the top of the cap) Magenta 2-way caps or Bellco Kap-uts with calculated air changes hr-1 of 2.25 and 1.43, respectively. Instantaneous PPF attenuations of 15% for Magenta caps and 23% for Bellco caps were also measured. The cultures were maintained for 28 d in an environmental growth chamber under Daylight fluorescent lamps with a 16 hr light/8 hr dark photoperiod, 200 μmol m-2s-1 PPF maintained for each cap type, constant 23 C, 65% relative humidity, and CO2 enrichment of 1000 μmol mol-1 external to the culture vessels. Results showed that increased plantlet height, fresh weight, and dry weight was obtained for plantlets cultured with Magenta caps. The differences in growth and internal CO2 concentration of the vessels correlated well with the difference in air exchange rates, suggesting that increased air exchange of culture vessels resulted in increased mixotrophic plantlet growth.

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Jonathan M. Frantz

tight, newly constructed, well-sealed greenhouse often has an air exchange rate of 0.5 to 1.0, while a poorly sealed or well-ventilated greenhouse may have an air exchange rate of 5.0 or more ( Aldrich and Bartok, 1994 ). Assuming the same environmental

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Creighton K. Thomas, Kwang Jin Kim and Stanley J. Kays

plant-free system with an identical air-exchange rate. Results Experimental removal rates for plants are typically measured as a concentration changes per time. The value of the parameter α can be extracted from such measurements if the concentration at

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Jonathan M. Frantz, Bryon Hand, Lee Buckingham and Somik Ghose

areas. Each selection adds a known amount of air exchanges as an approximation of system leakage ( Table 2 ). A tight, well-sealed greenhouse is considered to have an air exchange rate of 0.5 air exchange per hour, while an extremely leaky greenhouse has

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Heather L. Papinchak, E. Jay Holcomb, Teodora Orendovici Best and Dennis R. Decoteau

.2 mg·h −1 and laser printers on average produce 1.2 mg·h −1 ; however, concentrations could vary based on equipment maintenance ( Black and Worthan, 1999 ; Weschler, 2000 ). Depending on the air exchange rates between outdoor and indoor environments

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Kwang Jin Kim, Hyun Hwan Jung, Hyo Won Seo, Jung A. Lee and Stanley J. Kays

); and as the plant size increases, the removal potential per plant increases. The amount of plant material needed to reduce the VOC concentration within a structure varies with the steady-state VOC concentration, air exchange rate of the building, VOC

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Jennifer K. Boldt

–insulated knee wall, polycarbonate biwall side and end walls, air exchange rate of 1.65/h, energy curtain (WLE only), forced-air unit heaters burning natural gas, 45% heating efficiency, and nine 1000-W HPS lamps. Total energy costs for each treatment were

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Eric W. Kerschen, Caleb Garten, Kimberly A. Williams and Melanie M. Derby

( Ninomorua and Cohen, 1999 ), the recommended ventilation rate is two air changes per hour ( ASHRAE, 1999 ), requiring an air exchange rate of 45.3 m 3 ·h −1 (26.7 ft 3 /min). The molar air-flow rate, , can be obtained through the ideal gas law, where P

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Julie M. Tarara, Bernardo Chaves and Bernadine C. Strik

). Estimated from air exchange rates, wind speeds in other unventilated tubes with sealed bases (2.1 m tall, 10 cm diam) were 0.003 to 0.02 m·s −1 ( Bergez and Dupraz, 1997 , 2000 ). Dupraz and Bergez (1999) found no significant correlation between