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J.E. Cossentine, P.L. Sholberg, L.B.J. Jensen, K.E. Bedford and T.C. Shephard

Wooden fruit bins are a source of diapausing codling moth and postharvest pathogenic fungi. The redistribution of codling moths within bins is a problem where codling moth populations are being controlled by areawide codling moth sterile release programs, mating disruption programs, or both. Laboratory and fumigation chamber trials were carried out to determine the impact of relatively low levels of carbon dioxide on late-instar codling moth (Cydia pomonella L.) and two postharvest fruit pathogens, Penicillium expansum Link ex Thom and Botrytis cinerea Pers. ex Fr. Fumigation of diapausing codling moth with 40% CO2 in laboratory trials resulted in over 60% mortality after only 6 days of exposure and mortality increased with time of exposure. Significant mortality (68%) of diapausing codling moth larvae occurred after 14 days of exposure in the laboratory to 13% CO2 and a mean of 88% mortality was recorded after fumigation for 20 days. A significant number of P. expansum (46%) spores failed to germinate after laboratory exposure to 13% CO2 for 12 and 18 days respectively. Close to 100% of the P. expansum spores failed to germinate by day 20. When diapausing codling moth larvae and spores from both plant pathogens were placed in wooden fruit bins and fumigated for 21 days at 13% CO2, 75% of the diapausing codling moths died and 80% of the P. expansum spores failed to germinate. No effect on B. cinerea was observed.

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Maren J. Mochizuki, Oleg Daugovish, Miguel H. Ahumada, Shawn Ashkan and Carol J. Lovatt

More than 7 billion tons of greenhouse gases (GHG) were released in the United States in 2006; about 85% was carbon dioxide primarily attributable to the combustion of fossil fuels for the generation of electricity and for transportation [ U

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Nicolas Tremblay and André Gosselin

Since they grow nearly exponentially, plants in their juvenile phase can benefit more than mature ones of optimal growing conditions. Transplant production in greenhouses offers the opportunity to optimize growing factors in order to reduce production time and improve transplant quality. Carbon dioxide and light are the two driving forces of photosynthesis. Carbon dioxide concentration can be enriched in the greenhouse atmosphere, leading to heavier transplants with thicker leaves and reduced transpiration rates. Supplementary lighting is often considered as more effective than CO2 enrichment for transplant production. It can be used not only to speed up growth and produce higher quality plants, but also to help in production planning. However, residual effects on transplant field yield of CO2 enrichment or supplementary lighting are absent or, at the best, inconsistent.

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John Erwin and Esther Gesick

cultivars), and Swiss chard ( Beta vulgaris ; four cultivars) to irradiance and carbon dioxide concentration. The r 2 , mean square error (MSE), and “ k ” values (Mitscherlich function) fit to data are shown. Eq. [1] shows P n responses [ P n (I)] to

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Lloyd L. Nackley, Jig Han Jeong, Lorence R. Oki and Soo-Hyung Kim

< 0.05 ( Fig. 2 )]. Fig. 2. Biomass by constituent part of garlic plants grown in response to ambient and elevated carbon dioxide at three nitrogen (N) levels: low-, mid-, and high-N (n = 9–10, mean ± se ). ( A ) Leaf, ( B ) stem, ( C ) bulb, and ( D

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B. Todd Bunnell, Lambert B. McCarty, Roy B. Dodd, Hoke S. Hill and James J. Camberato

Increased soil moisture and temperature along with increased soil microbial and root activity during summer months elevate soil CO2 levels. Although previous research has demonstrated negative effects of high soil CO2 on growth of some plants, little is known concerning the impact high CO2 levels on creeping bentgrass (Agrostis palustris Huds.). The objective of this study was to investigate effects of varying levels of CO2 on the growth of creeping bentgrass. Growth cells were constructed to U.S. Golf Association (USGA) greens specification and creeping bentgrass was grown in the greenhouse. Three different levels of CO2 (2.5%, 5.0%, and 10.0%) were injected (for 1 minute every 2 hours) into the growth cells at a rate of 550 cm3·min-1. An untreated check, which did not have a gas mixture injected, maintained a CO2 concentration <1%. Gas injection occurred for 20 days to represent a run. Two runs were performed during the summer of 1999 on different growth cells. Visual turf quality ratings, encompassing turf color, health, density, and uniformity, were evaluated every 4 days on a 1-9 scale, with 9 = best turf and <7 being unacceptable. Soil cores were taken at the end of each run. Roots were separated from soil to measure root depth and mass. Turf quality was reduced to unacceptable levels with 10% CO2, but was unaffected at lower levels over the 20-day treatment period. Soil CO2 ≥2.5% reduced root mass and depth by 40% and 10%, respectively.

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T.K. Hartz, A. Baameur and D.B. Holt

The feasibility of field-scale CO2 enrichment of vegetable crops grown under tunnel culture was studied with cucumber (Cucumis saivus L. cv. Dasher II), summer squash (Cucurbita pepo L. cv. Gold Bar), and tomato (Lycopersicon escukntum Mill. cv. Bingo) grown under polyethylene tunnels. The drip irrigation system was used to uniformly deliver a CO2-enriched air stream independent of irrigation. Carbon dioxide was maintained between 700 and 1000 μl·liter-1 during daylight hours. Enrichment began immediately after crop establishment and continued for ≈4 weeks. At the end of the treatment phase, enrichment had significantly increased plant dry weight in the 2 years of tests. This growth advantage continued through harvest, with enriched cucumber, squash, and tomato plots yielding 30%, 20%, and 32% more fruit, respectively, in 1989. In 1990, cucumber and squash yields were increased 20%, and 16%, respectively. As performed, the expense of CO2 enrichment represented less than a 10% increase in total preharvest costs. A similar test was conducted on fall-planted strawberries (Fragaria × ananassa Duch. cvs. Irvine and Chandler). Carbon dioxide enrichment under tunnel culture modestly increased `Irvine' yields but did not affect `Chandler'.

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S.R. Drake, T.A. Eisle and H. Waelti

`Delicious' apples were held in controlled atmosphere (CA) storage at various carbon dioxide (CO2) levels for 9 months. CO2 levels were either 1, 3, or 5% with an additional treatment that was increased by 1% every 6 weeks to a maximum of 5%. For each treatment oxygen was 1%, and storage temperature was 1°C. Little quality difference was noted for the `Delicious' apples immediately after storage or after an 8 day ripening period. Firmness, external or internal color, titratable acidity and amount of scald showed no difference among the different storage treatments. Total carbohydrates and fructose were higher in apples stored at CO2 levels above 1 %. Sensory panelists found no flavor difference in `Delicious' apples regardless of CO2 storage level atmospheres. If one considers the substantial cost savings that are possible with increased CO2 in the storage system, there is good reason to increase the CO2 storage level in long term storage.

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C.L. Mackowiak, R.M. Wheeler and N.C. Yorio

Leaf stomatal conductance was monitored with a steady-state porometer throughout growth and development of soybean and potato plants grown at 500, 1000, 5000, and 10,000 (potato only) μmol mol-1 carbon dioxide (CO2). All plants were grown hydroponically with a 12-hr photoperiod and 300 μmol m-2 s-1 PPF. As expected, conductance at 1000 was < 500 μmol mol-1 for both species, but conductance at 5000 and 10,000 μmol mol-1 was ≥ that at 500 μmol mol-1. Subsequent short-term (24-hr) tests with potato and wheat plants grown at 1000 μmol mol-1 showed that raising CO2 to approx. 10,000 μmol mol-1 or lowering CO2 to 400 μmol mol-1 increased conductance compared to 1000 μmol mol-1 for potato, while only lowering CO2 to 400 μmol mol-1 increased conductance for wheat. Furthermore, raising the CO2 to 10,000 μmol mol-1 increased dark-period conductance in comparison to 1000 μmol mol-1 for potato, while dark-period conductance for wheat leaves was low regardless of the CO2 concentration. Results suggest that very high CO2 levels (e.g. 5000 to 10,000 μmol mol-1) may substantially increase water use of certain crops.

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Carlos H. Crisosto, David Garner and Gayle Crisosto

Efficacy of controlled atmosphere (CA) conditions for decay control in 'Thompson Seedless' table grapes was evaluated during the 1998-2000 seasons. During the 1998 season, early (16.5% soluble solids concentration = SSC) and late harvested (19% SSC) grapes were exposed to 5%, 10%, 15%, 20%, or 25% CO2 combined with 3%, 6%, and 12% O2. In 1999 and 2000, 10% or 15% CO2 combined with 3%, 6%, or 12% O2 were used. In all trials, fruit were initially SO2 fumigated and air-stored grapes were used as controls. Storage atmospheres did not affect SSC, titratable acidity (TA), or sugar-to-acid ratio (SSC: TA). The main storage limitations for early harvested 'Thompson Seedless' table grapes were “off flavor” and rachis and berry browning development, which resulted from exposure to >10% CO2. However, ≥15% CO2 was needed to control total decay and nesting development independent of O2 concentrations. High carbon dioxide atmospheres (15% to 25%) were more effective in decay control without detrimental effects on quality when late harvested grapes were used. The combination of 15% CO2 with 3%, 6%, or 12% O2 is suggested for up to 3 months storage only for late harvested 'Thompson Seedless' table grapes; it should not be used for early harvested grapes.