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Hoogstraten, 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. Source

Van Delm T.,Research Center Hoogstraten | Melis P.,Research Center Hoogstraten | Stoffels K.,Research Center Hoogstraten | Van De Vyver F.,Catholic University of Leuven | Baets W.,Research Center Hoogstraten
Acta Horticulturae | Year: 2014

Short-day strawberry cultivars induce flowers principally as a result of shorter photoperiod and lower temperatures. Dissection of the strawberry plants gives more information about plant quality. In the present study, the plant architecture is analysed weekly during plant production followed by a commercial strawberry production. An overview of plant development is achieved for strawberry cultivars 'Elsanta' and 'Clery'. The main aim is to understand which buds are responsible for the formation of inflorescences which produce strawberries for the first and the second crop. During the plant production, the two cultivars grow quite similar concerning architecture, but there is a difference in the start of generative growth. Also the development of the axillary bud just below the terminal inflorescence occurs at different dates. The second crop is a result of development of axillary buds just below the terminal inflorescence of the lateral crowns. The plant architecture at planting is not only determining the first, but also the second crop. Logically, the artificial conditions (heating and night-interruption treatments) in the greenhouse affect plant growth and flower induction. Flower development can continue under artificial lighting, but induction and initiation is inhibited by this treatment. Heating after a first crop gives the possibility for the further development of initiated flowers and is crucial for a successful second crop. Source

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. Source

Moerkens R.,Research Center Hoogstraten | Vanlommel W.,Research Center Hoogstraten | Vanderbruggen R.,Research Center Hoogstraten | Van Delm T.,Research Center Hoogstraten
Acta Horticulturae | Year: 2016

The total area of protected tomato crops in Belgium comprises 450 ha. In 2014 only 11 ha were lighted crops. One year later, this number increased with 400% towards 55 ha. 53 ha are equipped with high pressure sodium lamps (HPS), while the remaining 2 ha combine these lamps with light emitting diode (LED) assimilation light strains in between the crop. High pressure sodium lamps are not energy efficient. A lot of energy is wasted as warmth in comparison to LED light. In order to explore the full potential of LED light in protected tomato crops in combination with high pressure sodium lamps, a trial was set up at Research Centre Hoogstraten, Belgium in October 2014. High pressure sodium lamps (SON-T, Philips) of 169 μmol m-2 s-1 were installed in a tomato greenhouse compartment of 500 m2. In four plant rows (total: 100 m2) a combination with LED assimilation light (two interlight modules of 55 μmol m-2 s-1) was made. These two LEDs were hung horizontally on top of each other at a distance of 70 cm. The height relative to the plant was adjustable according to the cropping stage. Two tomato cultivars were planted on the October 22, 2014, each at two different plant distances (3.33 and 4.17 stems m-2). A comparison in crop parameters and production was made for each cultivar at both plant distances grown under high pressure sodium lamps with or without additional LED assimilation light. Results are very promising for both cultivars with increased yields of 20% with HPS and LED light. For practice, more research is needed to optimize plant distances, light strategies and light intensities to make the technology more profitable and durable. Source

Van Delm T.,Research Center Hoogstraten | Melis P.,Research Center Hoogstraten | Stoffels K.,Research Center Hoogstraten | Baets W.,Research Center Hoogstraten
Acta Horticulturae | Year: 2014

Powdery mildew (Podosphaera aphanis) is one of the most common diseases in strawberry cultivation, and is mainly controlled by regular chemical interventions. In view of sustainable strawberry cultivation and the decrease of residues, the use of UV-c light can be a good alternative for controlling powdery mildew. Three different trials have been done investigating the possibilities of UV-c treatments on strawberry plants in commercial production systems, whether or not in combination with a biological preventive product (Vacciplant - laminarin). A high and a low dose were tested in the first trial in a commercial production. In a second trial on the regrowth of cut plants, different intervals and two doses were compared, and also the combination with Vacciplant was tested. The last trial in a commercial greenhouse production system compares the UV-c treatment in combination with Vacciplant with a chemical and an untreated control. Results show that UV-c treatments are able to reduce and even control powdery mildew, although there are some points of interest. It is important to use the right dose and treatment interval in order to prevent damage to the plants. Also the positioning of the lamps is important for reaching a satisfying result. Depending on the pressure, the use of chemical products can be avoided or reduced. In combination with Vacciplant, this technique is promising for sustainable powdery mildew control in commercial strawberry production. Source

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