Climate Control in the Summer Season: A Comparative Study of External Mobile Shading and Fog System

Lorenzo, P.; Sánchez-Guerrero, M.C.; Medrano, E.; García, Mariangel; Caparrós, I.; Coelho, Gabriel Lins de Holanda; Giménez, Marcos H.

doi:10.17660/actahortic.2004.659.23

Cited by 12 publications

(7 citation statements)

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“…Dynamic shadowing systems that only reduce radiation at certain times of the day, when conditions are most stressful, result in smaller reductions in yield than in the intercepted radiation (De Koning, 1988, as reported by Stanghellini, 1994). Lorenzo et al (2003Lorenzo et al ( , 2004 pointed out the benefits of using external greenhouse mobile shading to control climate conditions in Mediterranean greenhouses during hot periods and highlighted its positive effect on fruit quality, as physiological disorders Shading screens for the improvement of the night-time climate of unheated greenhouses such as BER (blossom end root) were reduced. In addition, shading diminishes canopy transpiration as well as water uptake by crops, thus improving the efficiency of water use.…”

Section: Introductionmentioning

confidence: 99%

Shading screens for the improvement of the night time climate of unheated greenhouses

Montero¹,

Muñoz²,

Sánchez-Guerrero

et al. 2013

Span. j. agric. res.

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The objective of this work was to study the effect of shading screens, normally used during the day for cooling purposes, on the night-time climate of unheated greenhouses. For this purpose, first a number of experimental measurements were taken during cold nights to characterise the greenhouse climate both with and without an aluminised external screen. Secondly a Computational Fluid Dynamic (CFD) model of greenhouse was developed. After validation of the model by comparison with experimental data, the model was used to simulate the greenhouse climate for different sky conditions ranging from cloudless to overcast nights. Simulations were performed for a greenhouse with internal and external shading screens and for the same greenhouse without screens. Experimental results showed the positive effect of an external shading screen, whose use increased night-time temperature and reduced the risk of thermal inversion. Its effect was much stronger under clear sky conditions. The CFD model supported this conclusion and provided a detailed explanation of the temperature behaviour of all the greenhouse types considered. CFD simulations proved that an aluminised screen placed inside the greenhouse at gutter height gave the greatest thermal increase. Therefore, external or internal screens can help to increase the sustainability of greenhouse production in areas with mild winter climates by enhancing the use of solar energy stored in the greenhouse soil during the previous day and released at night-time.

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Section: Introductionmentioning

confidence: 99%

Shading screens for the improvement of the night time climate of unheated greenhouses

Montero¹,

Muñoz²,

Sánchez-Guerrero

et al. 2013

Span. j. agric. res.

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“…In fact, shading is one of the conventional and familiar techniques used by growers to decrease solar radiation and reduce air and leaf temperatures (Sandri et al, 2003). Many methods of shading such as curtains (Lorenzo et al, 2004), whitewash (Fernandez-Rodriguez et al, 2000), and new covering materials (Kittas and Baille, 1998) have been used to reduce plant damage related to high radiation and excess temperature in the summer. Shade helps plants by providing optimum conditions for leaf transpiration (Medrano et al, 2004) and carbone dioxide (CO 2 ) uptake (Fanjul et al, 1985), lowering air VPD (Lorenzo et al, 2003) and preventing high temperature stress (Jackson et al, 1983).…”

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confidence: 99%

Effects of Shading Using a Retractable Liquid Foam Technology on Greenhouse and Plant Microclimates

Aberkani

Hao

Halleux

et al. 2010

hortte

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Climate control is an important aspect of greenhouse crop management. Shading is one popular method for reducing excess solar heat radiation and high air temperatures in the greenhouse during the summer season. A new innovative technology has recently been developed and is based on the injection of liquid foam between the double layers of polyethylene of the greenhouse roof. The foam can be used as a shading method during the warm days of the summer. This is the first investigation into the effect of shading using the liquid foam technology on greenhouse and plant microclimates. Our research was conducted over 2 years in two different areas of Canada. Experimental greenhouses were retrofitted with the new technology. Tomato (Solanum lycopersicum) and sweet pepper (Capsicum annuum) were transplanted. Two shading strategies were used: 1) comparison of a conventional nonmovable shading curtain to the liquid foam shading system and application of liquid foam shading based only on outside global solar radiation; and 2) application of foam shading based on both outside global solar radiation and greenhouse air temperature. Data on the greenhouse microclimate (global solar radiation, air temperature, and relative humidity), the canopy microclimate (leaf and bottom fruit temperatures), and ventilation (opening/closing) were recorded. Our study showed that the retractable liquid foam technology improved greenhouse climate. Under some conditions (very sunny and hot days), a large difference in air temperature (up to 6 °C) was noted between the unshaded and shaded greenhouses as a result of liquid foam application (40% to 65% shading). Foam shading also increased relative humidity by 5% to 12%. Furthermore, bottom fruit temperatures stayed cooler 3 h after shading treatment was stopped. As well, a reduction in ventilation needs was observed with liquid foam shading.

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“…Although the total yield can be reduced linearly with the augmentation of shading [17,79], positive effects can be produced in the yield of marketable fruit. Shading can diminish the incidence of blossom-end rot (BER) in tomatoes [38] and, as a consequence, reduce the non-marketable yield [51]. The main drawback of cover whitening against other passive or active cooling methods (i.e., external/internal net shading, fog) is that it may negatively affect the photosynthetic rate, crop growth, and production, as it reduces light in hours when it is not in excess.…”

Section: Tomato Productionmentioning

confidence: 99%

“…When greenhouses present an insufficient capacity of natural ventilation, whitening is adopted as the standard practice with problems of heterogeneity and severe reductions in PAR radiation that diminish the assimilation potential of crop species with high light saturation [51]. The flow of photosynthetic activity is more uniform under the influence of a shading screen than under whitening [80], which may suggest a large spatial variation in light uniformity.…”

Section: Tomato Productionmentioning

confidence: 99%

“…However, the reduction of solar radiation by shading can produce positive effects, such as a diminution of the air temperature and the water consumption by irrigation [40,50]. Thus, the use of mobile shading can improve water use efficiency, reducing crop transpiration [32,51]. Close attention should be paid to the date of application, duration, and dose, with the aim of not drastically reducing physiological flows in the lower strata of the plant canopy [52].…”

Section: Introductionmentioning

confidence: 99%

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Effects of Cover Whitening Concentrations on the Microclimate and on the Development and Yield of Tomato (Lycopersicon esculentum Mill.) Inside Mediterranean Greenhouses

et al. 2020

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This work analyzes the influence of whitening a greenhouse roof on the microclimate and yield of a tomato crop. In the west sectors of two multi-span greenhouses, a whitening concentration of 0.250 kg L−1 was used as a control. In an autumn–winter cycle, a lower (0.125 kg L−1) and an increased (0.500 kg L−1) concentration were used in the east sectors of greenhouses 1 and 2. In a spring–summer cycle, the whitening concentrations in the east were varied depending on outside temperature. The effect of whitening on photosynthetic activity, production, plants’ morphological parameters, and the quality of the fruits were also analyzed. To evaluate the effect on microclimate, solar and photosynthetically active (PAR) radiations, air and soil temperatures, and heat flux in the soil were measured in greenhouse 1. Results show that excessive whitening leads to reductions of inside PAR radiation that decreases photosynthesis and crop yield. A whitening concentration of 0.500 kg L−1 is proposed at the beginning of the autumn–winter crop cycle, washing the cover when inside temperature drops to 35 °C. At the end of the spring–summer cycle, a concentration of 0.125 kg L−1 is recommended when inside temperature increases to 35 °C.

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Climate Control in the Summer Season: A Comparative Study of External Mobile Shading and Fog System

Cited by 12 publications

References 0 publications

Shading screens for the improvement of the night time climate of unheated greenhouses

Shading screens for the improvement of the night time climate of unheated greenhouses

Effects of Shading Using a Retractable Liquid Foam Technology on Greenhouse and Plant Microclimates

Effects of Cover Whitening Concentrations on the Microclimate and on the Development and Yield of Tomato (Lycopersicon esculentum Mill.) Inside Mediterranean Greenhouses

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