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Sint-Katelijne-Waver, Belgium

Hanssen I.M.,Scientia Terrae Research Institute | Gutierrez-Aguirre I.,Slovenian National Institute of Biology | Paeleman A.,Scientia Terrae Research Institute | Goen K.,Research Center Hoogstraten | And 5 more authors.
Plant Pathology | Year: 2010

The potential of three mild Pepino mosaic virus (PepMV) isolates, belonging to the CH2, EU and LP genotypes, to protect a tomato (Solanum lycopersicum) crop against an aggressive challenge isolate of the CH2 genotype was assessed in greenhouse trials and PepMV symptoms were rated at regular time points. After challenge infection, enhanced symptom display was recorded in plants that were pre-inoculated with a protector isolate belonging to a different genotype (EU, LP) from the challenge isolate. A quantitative genotype-specific TaqMan assay revealed that in these plants, the accumulation of the challenge isolate only temporarily slowed down. By contrast, efficient cross-protection was obtained using the mild isolate of the CH2 genotype, and in this case the challenge isolate was barely detectable in the pre-inoculated plants. These results suggest that the interaction between PepMV isolates largely depends on RNA sequence homology and that post-transcriptional gene silencing plays an important role in cross-protection. © 2009 BSPP.

Van Den Bulck N.,Flemish Institute for Technological Research | Coomans M.,Flemish Institute for Technological Research | Wittemans L.,Research Station for Vegetable Production | Hanssens J.,Ghent University | Steppe K.,Ghent University
Energy and Buildings | Year: 2013

Greenhouse cultivation is an intensive part of horticulture in Flanders in which large production volumes are accompanied by significant energy consumptions. Demand for energy efficient solutions is rising due to fluctuations and increases in energy prices, ongoing pressure from international competition and incentives from governments in the scope of climate change. Over a two-year period, a compact ventilation concept was monitored in a Belgian semi-closed greenhouse. The installation was one of the first ventilation concepts in Belgium and is based on intensive thermal screening in combination with controlled ventilation. Air flow rates, indoor and outdoor climatic parameters were monitored as well as the energy flows of the ventilation unit, the energy demand of the greenhouse and the crop results. The measured energy consumption of the concept was 9.6% higher than the reference case in 2010, partly due to its location within the greenhouse complex. However, during the second growing season of 2011, two more similar compartments were compared, showing the potential of the ventilation concept with a 12% energy saving. In addition, improved crop growing conditions become possible as the installation allows for a better control of the greenhouse climate. © 2012 Elsevier B.V.

Coomans M.,Flemish Institute for Technological Research | Allaerts K.,Flemish Institute for Technological Research | Wittemans L.,Research Station for Vegetable Production | Pinxteren D.,Research Center Hoogstraten
Energy Conversion and Management | Year: 2013

Horticulture is an energy intensive industry when dealing with cold climates such as Western Europe. High energy prices and on-going pressure from international competition are raising demand for energy efficient solutions. In search of reducing greenhouse energy consumption, this study investigates semi-closed systems combining controlled mechanical and natural ventilation with thermal screens. Ventilated greenhouse systems (semi-closed) have been implemented in the greenhouse compartments of two Belgian horticulture research facilities: the Research Station for Vegetable Production Sint-Katelijne-Waver (PSKW) and the Research Center Hoogstraten (PCH). Additionally, two reference compartments were included for comparison of the results. The greenhouses were part of a long-term monitoring campaign in which detailed measurements with a high time resolution were gathered by a central monitoring system. A large amount of data was processed and analysed, including outdoor and indoor climatic parameters, system controls and installation measurements. The ventilated greenhouses obtained energy savings of 13% and 28% for PSKW and PCH respectively, without substantial impact on crop production or indoor climate conditions when compared to the reference compartments. A considerable amount of heat was recovered by the heat recuperation stage in the ventilation unit of PCH, accounting for 12% of the total heat demand. In general, it was demonstrated that the greenhouse heat demand can be reduced significantly by controlled dehumidification with mechanical ventilation, especially during spring and autumn. © 2013 Elsevier Ltd. All rights reserved.

Van den Bulck N.,Flemish Institute for Technological Research | Coomans M.,Flemish Institute for Technological Research | Wittemans L.,Research Station for Vegetable Production | Goen K.,Research Center Hoogstraten | And 4 more authors.
Proceedings of the 25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012 | Year: 2012

Greenhouse plant cultivation is an energy-demanding industry, especially in colder regions like Western Europe. The increase in yield and the year-round production of greenhouse cultivation comes with high investment and operational costs in comparison to other agricultural activities. Due to the high percentage of energy costs in the total production cost, alternative energy systems are needed. An innovative ventilation system can provide optimal climatic conditions inside the greenhouse without the excessive heat loss of a traditional installation. Therefore, an innovative ventilation-concept has been implemented in the Research Station for Vegetable Production at Sint-Katelijne-Waver, Belgium, and results have been compared to a traditional operated greenhouse compartment. The pilot compartment is equipped with double thermal screens, which reduce the heat loss to the ambient environment. Furthermore, the mechanical ventilation enables the extensive use of these double screens together with a better control of the incoming air rate compared to the traditional ventilation method of opening greenhouse windows. In both the ventilated and traditional greenhouse, temperature, relative humidity, CO2 concentration, energy consumption and control strategies were registered during the first year of use in 2010. In this paper these measurements are presented to determine the potential of the concept in terms of energy savings, improved yield and investment costs.

Hanssens J.,Ghent University | De Swaef T.,Ghent University | Wittemans L.,Research Station for Vegetable Production | Goen K.,Horticulture Research Center Hoogstraten | And 3 more authors.
Acta Horticulturae | Year: 2012

Maintaining good plant water status is crucial for optimal production and quality of tomato in greenhouses. Various new climate control technologies have been introduced to make greenhouse cultivation more energy-efficient, resulting in a modified greenhouse climate. Recently, there has been growing interest in the use of plant-based methods to steer the climate. Monitoring stem diameter variations (SDV) has been extensively studied in tree species, but is also very promising for herbaceous crops. Stem and fruit diameter variations provide crucial information about plant water status, though unambiguous interpretation of these dynamics is often difficult. Mechanistic modelling can help to elucidate the mechanisms driving plant behaviour and is therefore an important tool for interpreting the dynamic response of the plants to changes in microclimate. In the present study, tomato plants (Solanum lycopersicum L.) were subjected to elevated air temperature (Ta) and vapour pressure deficit (VPD), while SDV, sap flow and fruit growth were continuously monitored. Results indicated that stem shrinkage became more pronounced and fruits shrank during periods of high Ta and VPD. Simulation results showed that reduced fruit growth resulted from both increased fruit transpiration and decreased phloem inflow. Moreover, xylem backflow appeared when Ta and VPD reached maximum values. It was demonstrated that the reduced fruit growth resulted mainly from changes in stem water potential, rather than fruit water potential.

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