Belgian research institute seeks solutions to cross-border vegetable challenges
PSKW researches vegetable production across a 1ha greenhouse and 8ha of open fields

Belgian research institute seeks solutions to cross-border vegetable challenges

Gill McShane

Belgium’s Research Station for Vegetable Production (Proefstation voor de Groenteteelt or PSKW) in Flanders focuses on research, development and innovation for the fresh vegetable industry through practical and applied research. As part of a recent tour of Belgium’s fruit and vegetable sector, Produce Business UK visited the station to discover what projects would interest UK grower-suppliers, buyers and research institutes. What follows is a run-down of our findings

Founded over 50 years ago, the not-for-profit PSKW has been situated at its current base in Sint-Katelijne-Waver – at the traditional heart of Belgium’s vegetable production – since 2007 when a purpose-built station was constructed and adapted to the needs of the growers.

The site, which employs 40 people, features a 1ha greenhouse for the trial production of tomatoes, sweet peppers, lettuce, cucumbers, courgette, and 8ha of open fields across different areas for lettuce, leeks, cabbage, cauliflower, Brussels sprouts, asparagus and courgette, among others. Current projects include research into lighted production, pests and disease, varieties, production techniques and energy-saving solutions.

Lieve Wittemans, a specialist in glasshouse production and scientific assistant at PSKW, explains that the facilities are constantly updated to enable the station to carry out research at the same level as growers’ own production. PSKW also collaborates with various partners, such as other (practical) research stations, universities or research institutes, both within Belgium and across Europe.

Workers at PSKW Research Station in Belgium

Projects of interest to the UK

A running theme across all of PSKW’s research projects is product quality. This, says Wittemans, is to ensure that no matter what the station trials or researches the resulting application will allow growers to produce plants of optimum quality as required by retailers and buyers worldwide.

“We do a lot of shelf-life trials in order to verify that the treatments we apply – whether a change in variety, climatic condition, composition of nutrient solution etc. – does not harm the quality of the product,” she explains.

Indeed, quality is so important to its activities that PSKW even advises Belgium’s produce auctions on what quality standards to set for Belgian fresh fruits and vegetables. Based on its analysis, the station has so far helped to set the objective standards for Belgian tomatoes, and the same principle is now being applied to cucumbers and sweet peppers.

For UK grower-suppliers and buyers, Wittemans suggests topics regularly researched by PSKW like disease, varieties and production techniques are always of interest to the industry.


“Diseases like Pepino Mosaic Virus [in glasshouse tomatoes] and excessive root growth are as much an issue in UK tomato production as here in Belgium,” she points out.

“Together with our other project partners we have developed a vaccine against Pepino Mosaic Virus, PMV-01, which is now commercially available in Belgium, the Netherlands, Switzerland, France, Germany and Morocco. We expect permission for use of the vaccine in the UK in 2016.

“We are also monitoring pests, mainly in tomatoes, to find a good monitoring method that’s not too time consuming.”

For cucumber producers, PSKW is researching Mycosphaerella disease (Didymella bryoniae which causes Gummy Stem Blight in cucurbits), while in sweet peppers the institute is making progress in finding a solution to control internal fruit rot caused by Fusarium disease.

“We’re doing variety trials for cucumbers to find a solution to the fungal disease Mycosphaerella, which causes fruit rot that is often not apparent until late in the product’s shelf-life,” says Wittemans.

“It’s a problem that’s seen everywhere by cucumber growers. For years Mycosphaerella has been one of the most important problems in the production of cucumbers. This fungus can infect plants and fruits, and fruit rot causes the most important economical damage. Research shows that 72% of growers have experienced damage from infection with this fungus.”

As part of the research PSKW wants to find a sustainable control strategy for the disease. In order to achieve this, the station is working on several levels. Varieties are being evaluated for their resistance to the disease, while PSKW is seeking to optimise the climate conditions in the greenhouse to avoid infections or the spread of the fungus. Another strategy it will test are biocontrol organisms.

Having only started last summer, the trials are still ongoing. “Until now we have gained more insight into how plants are infected and the conditions for infection,” reveals Wittemans. “Using this information, we want to take the step towards solving the problem. The varieties we’re testing are the commercially available varieties as well as new varieties that we’re testing in our variety trials.”

Artificial lighting: lettuce, tomatoes, sweet peppers & strawberries

PSKW’s development and evaluation of artificial lighting and new energy-saving greenhouse concepts will also interest UK growers and supply chain partners, according to Wittemans.

“Last year we started a research project on artificial lighting – high pressure sodium lamps and LEDs – for lettuce, tomatoes and sweet peppers,” she says. “The number of growers of these lighted crops in Belgium had been stable. Then a couple of years ago the industry showed an interest in looking for opportunities to expand.

“In Holland, one third of tomato production is under lighting. In Belgium we are following the evolution of that trend. In just two years, lighted tomato production has increased from 17ha to 85ha in Belgium.”

Wittemans says Dutch growers were motivated to switch to artificial lighting thanks to their close relationships with buyers.

“Retailers want products to be available throughout the whole year,” she states. “In order to meet this demand, growers installed artificial lights in part of their greenhouses and are planting on different dates in the different greenhouses.

“In Belgium, meanwhile, almost all produce is sold via the cooperatives [auctions]. The demand for produce in the winter time is filled in with produce from members who, for example, have an autumn crop of tomatoes, which produces from November until the end of January.”

PSKW’s artificial lighting research is focusing on two areas of optimisation – finding the best distance between the plants and the lamps, and the best position of the lamps for light distribution (either on top of the plants or in between). Different varieties are being tested, as well as leaf picking techniques and the distance between the wires for the plants to grow along. Different light intensities are also being tested.

Wittemans says information is already available from the trials into lettuce. “The LED lighting trial versus standard lamps is presenting interesting results for energy savings. But the main obstacle [to growers applying LED lighting] is the cost of investment. But there could be long-term gains. Belgian lettuce growers in particular have expressed a willingness to switch to LED bulbs if the prices are reduced.”

Meanwhile, the trials into tomatoes and sweet peppers are ongoing and no results have been published yet. In early March PSKW will organise an open day for growers and suppliers where it will present the findings to date. Further results will be published during the course of the project, which ends in August 2019.

Belgium Research Station for Vegetable Growth artificial lighting trial for tomatoes

In addition, LED lighting trials for strawberry production are being carried out by Proefcentrum Hoogstraten (PCH) – a research centre in the north of Belgium, near Antwerp, which is a younger production area with larger greenhouses. The ‘Lightman’ project focuses on artificial lighting in tomatoes, lettuce and strawberries, and runs in conjunction with PSKW, the University of Ghent and the Thomas More university college in Flanders.

“Normally, there is no strawberry production [in Belgium] in the months of January and February,” explains Wittemans. “Using artificial light, the researchers have proven that it is possible to have year-round Belgian strawberry production with high quality fruit.

“We are exploring the boundaries with strawberries and looking for possibilities. We’re asking questions like: how much light should you give to the plants?; what’s the optimum level of light?; and what are the possibilities with LED lights?”

Energy saving

With grower-suppliers increasingly seeking to save energy for environmental and economical reasons, PSKW is currently building an innovative greenhouse to research ways to conserve energy.

“There’s an opportunity to save energy in greenhouses,” claims Wittemans. “Plants produce moisture and in winter when the windows of the greenhouse are open, heat is lost as the moisture is released.

“So, we are looking into the idea of having two mobile energy screens under one roof to stop the heat from being lost. A separate system will also catch the humidity released from the plants, and that air will be run through a dehumidification machine in order to recirculate the air in the greenhouse.”

The EXE-kas (EXery Efficient) greenhouse consists of an efficient dehumidification device (vapour heat pump), Energy Balancing (EB) screens and an efficient CO2 generation system (CO2P). Two elements of EXE-kas, namely the vapour heat pump and the EB day screens, are being developed in cooperation with several scientific and industrial partners.

The vapour heat pump consists of a heat mass exchanger in which air is dried through contact with a salt solution, and a mechanical vapour compression unit that concentrates the salt solution. The EB-day screen features a combination of two screens with higher light transmittance and improved thermal properties.

“In 2015, these devices were engineered and produced,” says Wittemans. “In 2016 they will be tested in an experimental greenhouse of 720m². With this energy saving greenhouse concept we aim to reduce the net primary energy consumption by half. We will measure if we can realise these objectives and we will optimise the growing and climate strategy in this type of greenhouse.”

The project sees the collaboration of the universities of Ghent and Leuven, as well as companies including Dutch manufacturer HiPlast (which is supplying the screens) and a Belgian company for the heat pump. “We are using the experts,” says Wittemans.

Labour saving

Recognising that many industrial sectors are becoming highly automatised, while automation in greenhouse vegetable production lags behind, PSKW is also trialling a year-round harvesting robot system for sweet peppers together with the University of Wageningen in the Netherlands, the University of Umea in Sweden and the University of Ben Gurion in Israel.

“Labour is an issue in Belgium, and all over it seems,” Wittemans says. “The availability of skilled workforces willing to do repetitive tasks in sometimes harsh greenhouse climate conditions is decreasing. Postharvest solutions, robots and machines have made their entrance, but in the greenhouse sector most manipulations are still done manually.”

When it comes to sweet peppers, Wittemans says the crop is faced with the additional challenge of being difficult to harvest without damaging the vegetable, as well as knowing when is the optimum time is to pick.

“For the moment, the challenge for harvesting sweet pepper is the main focus, although it’s always possible there will be a spin-off to other crops,” she says.

More information can be found on


Another research project well underway at PSKW is the trial of a mobile gully system (MGS) for three types of lettuce – lollo rosso, red oak and lollo bionda. Already, Wittemans says the concept is proving to reward growers with more output per square metre and more control over their growing environment.

“MGS works by moving the plants apart as they grow to create more space as the plants get bigger,” she explains. “There is also a recirculation system in place for the application of water and nutrients, so the plant gets exactly what it needs and there are no soil-borne diseases.

“With the MGS you can produce more lettuce per year – there are eight to nine growing cycles versus five to six with soil production. One producer using MGS claims he is growing as much on 1ha now as he used to on 4ha.

“The lettuce can also be sold as a living plant for added value. And growers can complement the MGS with (LED) lighting – the investment is justifiable because you get more plants per m2 and additional growing cycles.

“There are ergonomic advantages too,” adds Wittemans. “The MGS is set up at waist height so there’s no bending down to soil level to tend to the crop or harvest.”

Belgium Research Station for Vegetable Growth mobile gully system trial for lettuce

Collaborating with the UK

In addition to its on-site research in Sint-Katelijne Waver, PSKW carries out certain trials on growers’ own fields where testing requires specific local conditions, such as soils. Where the station lacks the knowledge or capacity to carry out certain research projects, it works with other partners.

“Most of our research partners are situated in Flanders,” she says. “However, Flanders is a very small area, plus we [at PSKW] can be limited on space sometimes, so we like to collaborate with other research institutes.

“Many of the problems we’re confronted with are often problems in other countries – they don’t stop at the Flemish border, and since some research questions are universal, we look for collaboration with foreign research institutes.”

Although PSKW doesn’t run many international projects, Wittemans says there is certainly an interest to collaborate with research institutes in the UK. “Contacts can be informal (e.g. visits) or through collaboration in joint projects,” she explains.

One initiative that might have been of interest to UK research partners is a new project that’s starting shortly on excessive root growth (or ‘root mat’) with France and Switzerland.

“I know this is also an upcoming problem in the UK as well,” points out Wittemans. “On this occasion, the UK did not answer the call for project participants, so we couldn’t take on a partner in the UK. But we are active in many research fields, so undoubtedly there will be several things we have in common [with UK institutes].”

Indeed, PSKW is already working as the coordinator together with 23 European partners on a sustainable water use project called FERTINNOWA, which includes East Malling Research and The Agriculture and Horticulture Development Board (AHDB) as UK participants.

“In European countries, the cultivation of fertigated crops experiences a scarcity of water, and the intensity of cultivation poses significant risks to water quality,” points out Wittemans. “With the FERTINNOWA thematic network we want to create a meta-knowledge database on innovative technologies and practices for fertigation of horticultural crops and to build a knowledge exchange platform to evaluate existing and novel technologies (innovation potential, synergies, gaps, barriers) for fertigated crops and ensure wide dissemination to all stakeholders involved of the most promising technologies and best practices.”

Looking further ahead, Wittemans says PSKW’s future research will depend on the problems and questions it receives from growers. If the station is the right party to work on the project, and providing it has the necessary resources, PSKW will begin the research to try to solve the problem or answer the question.

“Last year we filed project proposals for the reduction of biofilms in irrigation systems and on root exudates, and we would like to continue our research on energy saving greenhouse concepts,” Wittemans notes. “For the moment it is, however, not sure if these project proposals will be approved.

“On the other hand, questions from growers or growers’ cooperatives are often urgent and sometimes they cannot wait until a project is written, filed and approved. In that case we try to start up small-scale, preliminary research with the means we have available.”

Working with growers

Financing for PSKW comes from three areas: the Belgian vegetable sector (via grower contributions paid to the auctions), the Belgian government (through fixed subsidies and funding for applied projects) and PSKW’s own income (membership).

Importantly, the research station relies on its close relationships with growers, in particular. While the station is independent of growers and grower groups, producers are members on PSKW’s board of directors and have involvement in the daily administration of the station.

“We’re here because of the growers, so it’s important to have a strong bond with them,” says Wittemans. “We have good relationships with both the auctions and the growers. We listen to their problems and we look for solutions. Since we do applied research, it’s our aim to offer solutions and advice for the growers.”

Membership is open to all – both within and outside of Belgium. The station organises open days (when members are encouraged to visit to look around), and publishes a magazine called Proeftuinnieuws with its news and results.

“We are happy to share the results of any of our projects – all you have to do is to become a member and you’ll receive all of our publications and project results information,” points out Wittemans. “And we purposely set the membership fee low to keep it open to all.”

Membership costs for PSKW vary:

PSKW membership rates. jpg

The Research Station for Vegetable Production’s (PSKW) website is in the process of being translated into English.

Watch this space for further articles from PBUK’s recent trip to Belgium…



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