Effect of Natural Ventilation Rate on Relative Humidity and Water Use for Fog Cooling in a Semiarid Greenhouse

Sase, Sadanori; Ishii, Masahisa; Moriyama, Hideki; Kubota, Chieri; Kurata, K.; Hayashi, Makio; Sabeh, Nadia; Romero, Pedro López; Giacomelli, G. A.

doi:10.17660/actahortic.2006.719.43

Cited by 17 publications

(10 citation statements)

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“…The higher humidity levels seem to stimulate cucumber leaf growth (LAI), which was also reported in a previous paper by Körner and Challa [43]. A decrease of the levels of a greenhouse's air relative humidity has also been reported by many authors as affected by an increase in the ventilation rate [44,45]. However, higher values of LAI were not able to explain lower transpiration values comparing with the Exp.…”

Section: Discussionsupporting

confidence: 52%

“…As expected, a close correlation was observed between the transpiration rate and the amount of nutrient outflow from the greenhouse to the environment (i.e., drainage). As indicated in Table 3, the mean drainage recorded values over the course of a 10-day representative period (44)(45)(46)(47)(48)(49)(50)(51)(52)(53) was between 30-35% (T1) and around 20% (T2) in both experiments in CA. In CB, a higher drainage amount was recorded, with greater differences between the two cooling systems tested during Exp.…”

Section: Transpiration and Irrigation Water Use Efficiencymentioning

confidence: 85%

“…For calculated leaf area index (LAI: m 2 leaf m −2 ground) plant destructive measurements were repeated four times (30,45,60, 75 DAT) in Exp. 1 and Exp.…”

Section: Data Recorded Sampling and Measurementsmentioning

confidence: 99%

“…1 and Exp. 2, were repeated five times (15,30,45,60, 75 DAT) in three labeled plants and on three randomly selected for T1 and T2, in each greenhouse compartment. Harvesting was made two to three times per week during morning hours, and started 25 DAT (Exp.…”

Section: Data Recorded Sampling and Measurementsmentioning

confidence: 99%

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Effects of Cooling Systems on Greenhouse Microclimate and Cucumber Growth under Mediterranean Climatic Conditions

et al. 2019

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Two experiments were conducted in different cropping seasons under Mediterranean climatic conditions to investigate the impact of two cooling systems (fan-pad evaporative as opposed to fan ventilation) on greenhouse microclimate and soilless cucumber growth. The second objective of the experiment was to determine the most appropriate irrigation regime (between 0.24 and 0.32 L m−2) in relation to crop water uptake and greenhouse fertigation effluents. The use of a fan ventilation system enhanced the vapor pressure deficit; thus, the crop transpiration improved by 60% in relation to the transpiration rates of plants grown under the fan-pad system. Higher transpiration rates alleviated the heat load as the external–inside greenhouse air differences declined from 6.2 °C to 3 °C. The leaf–air temperature differential indicated that plants were not facing any water stress conditions for both cooling systems tested; however, fan ventilation reduced drainage emissions outflows (95% decrease) compared with evaporative cooling. Results also demonstrated that an irrigation regime of 0.24 L m−2 can be applied successfully in soilless cucumber crops, keeping the drainage to a minimum (20% of the nutrient solution supply). These results suggest that fan ventilation cooling system in conjugation with an appropriate irrigation regime prevents overheating and minimizes the nutrient and water losses in spring-grown soilless cucumber crops in Mediterranean greenhouses without compromising yield.

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Section: Discussionsupporting

confidence: 52%

Section: Transpiration and Irrigation Water Use Efficiencymentioning

confidence: 85%

“…For calculated leaf area index (LAI: m 2 leaf m −2 ground) plant destructive measurements were repeated four times (30,45,60, 75 DAT) in Exp. 1 and Exp.…”

Section: Data Recorded Sampling and Measurementsmentioning

confidence: 99%

Section: Data Recorded Sampling and Measurementsmentioning

confidence: 99%

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Effects of Cooling Systems on Greenhouse Microclimate and Cucumber Growth under Mediterranean Climatic Conditions

et al. 2019

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“…regions to save water use Sase et al (2006) proposed a unique control algorithm that incorporates the adjustment of vent openings. Observations were completed in the greenhouse without plants growing early in June 2005.…”

Section: New Strategy Of Controlling Ventilation In Semiaridmentioning

confidence: 99%

Controlled Environment Agriculture for Effective Plant Production Systems in a Semiarid Greenhouse

Ishii

Sase

Moriyama

et al. 2016

JARQ

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Semiarid climate regions have great potential for productivity due to large amounts of solar radiation throughout year. However, these regions also have disadvantages, such as excessive air temperature and limited water use. Optimizing the ventilation rate and evapotranspiration during fog cooling in combination with natural ventilation will provide more favorable growing conditions for plants in a semiarid climate and allow less water use. A single-span greenhouse at The University of Arizona was used to investigate the fog cooling performance on clear days with excessively high air temperature. The environmental conditions and the natural ventilation rate were measured. The performance of fog cooling in combination with natural ventilation was compared with pad-and-fan cooling. Fog cooling and pad-and-fan cooling used 24 g m -2 min -1 and 41 g m -2 min -1 of water, respectively. The air relative humidity for fog cooling was slightly higher than that for pad-and-fan cooling, at approximately 35%. An English version of Visual VETH (ventilation-evapotranspiration-temperature-humidity) software was also developed. A cooling strategy devised for semiarid greenhouses found that the air relative humidity inside a greenhouse decreased with an increase in ventilation rate as expected from simulation based on steady-state energy balance equations, while the water use for fog cooling increased. A simple and unique control algorithm for fogging and ventilation inlet openings demonstrated the possibility of maintaining relative humidity and air temperature simultaneously within a desirable range while reducing the water use for fog cooling. The tomato plant canopy transpiration rate and the water balance relative to the natural ventilation rate in a fog-cooled greenhouse were also investigated. The transpiration rate increased linearly with an increase in vapor pressure deficit (VPD) of the air. At a lower ventilation rate made possible by reducing the ventilation inlet openings, total water use in the greenhouse decreased by 13% and relative humidity increased as was expected from the steady-state energy balance simulation. The decrease in canopy transpiration resulted from the decrease in VPD, and was at a magnitude greater than that of the fog evaporation rate under similar experimental conditions with relatively high humidity in the range of 70-94%. By optimizing the natural ventilation rate, the greenhouse could be effectively cooled with less water use. Arizona can be considered a model analogous to many other semiarid climate conditions. Due to the long history of greenhouse technology development, the application of greenhouse crop production to an area with excessive radiation and dry air remains a relatively new effort. We believe that our efforts will contribute not only to the American Southwest but also to enhancing the application of greenhouse technology for crop production in these climate regions worldwide, including Mexico, China, the Middle East and Africa.

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Cooling

Zabeltitz¹

2010

Integrated Greenhouse Systems for Mild Climates

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Effect of Natural Ventilation Rate on Relative Humidity and Water Use for Fog Cooling in a Semiarid Greenhouse

Cited by 17 publications

References 0 publications

Effects of Cooling Systems on Greenhouse Microclimate and Cucumber Growth under Mediterranean Climatic Conditions

Effects of Cooling Systems on Greenhouse Microclimate and Cucumber Growth under Mediterranean Climatic Conditions

Controlled Environment Agriculture for Effective Plant Production Systems in a Semiarid Greenhouse

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