New LED lamp rates highly in hybrid lighting trial

New LED lamp rates highly in hybrid lighting trial

A trial with hybrid lighting (SON-T + LED) at Dutch tomato nursery Gebroeders Koot has yielded good results. The LED lamp used in the trial, which was developed on British soil with Dutch input, offers several advantages. One stand-out benefit is its clever design which makes it easy to integrate into existing SON-T installations.

Yields up by more than nine percent after seven months (weeks 48-26). That was the auspicious outcome of a greenhouse trial at Prominent growers Gebroeders Koot in Poeldijk, the Netherlands, where a tomato crop grown under 150 μmol/m2/sec SON-T grow light was compared with an identical crop supplemented with 58 μmol deep red with a little blue LED light. Geert Koot, who had had no previous experience in growing under grow light, was very impressed. “I hadn’t expected the higher light level to make such a difference,” he says. “That will appeal to a lot of growers. The same goes for the lamp itself, which has a surprisingly simple design. It’s fully interchangeable with SON-T, so it fits seamlessly into an existing system.”
“A lot of thought has gone into the functional design,” cultivation specialist Maarten Klein adds. He and his assistant, Tim Valstar, oversaw the trial, which was run on behalf of the British LED manufacturer Plessey. Klein, who has had a lot of experience with grow light, developed this lamp in collaboration with the technology company.

Smarter design

“Most LED systems are difficult if not impossible to integrate into existing lighting installations,” Klein continues. “Growers looking to switch to hybrid lighting currently have to install a whole new system alongside their existing one, often with extra C profiles. That pushes up the cost and results in more light interception, which causes problems all year round. Plessey Semiconductors in Plymouth wanted to eliminate these problems.”
To test the practical value of the lamp in the greenhouse setting, Klein approached several Dutch nurseries. In addition to Gebroeders Koot, trial setups were installed at nearby alstroemeria and gerbera growers and a pot plant nursery.

Trial setup

Although Gebroeders Koot were not growing tomatoes under artificial lighting, they did have a SON-T system in place in a section that had previously been let to another grower. These 1000W lamps supplied 151 μmol/m2/s extra grow light and, of course, the usual radiated heat. LED lamps were added in one bay, ramping up the artificial light level to 209 μmol.
Tim Valstar assisted with the trial and, together with Geert Koot, took measurements in the trial and reference sections. All the relevant crop and fruit features of the variety grown, Brioso, were recorded, varying from growth rate and stem thickness to leaf size, leaf colour, fruit weight and Brix value.


The plants arrived in the greenhouse in week 46. “That’s later than the usual for an artificially lit Brioso crop – they would usually go in in mid-October – but the lighting period was long enough to get a reliable impression of any differences,” Koot says. “The plants developed well in both light environments. But the plants under the higher light level were that little bit stronger with slightly thicker stems and more dark green leaves.”
Due to the extra vigour, the plants under the hybrid lighting regime held the first trusses for longer and they were harvested a few days later than those in the reference sections. The higher yield potential quickly expressed itself in a higher average fruit weight. To maintain the desired fineness, one fruit more was kept on the truss (11 instead of 10) from the tenth truss onwards, without the plants forfeiting vigour.
Valstar: “After week 26 we stopped taking measurements and were able to take stock.” The harvest under the hybrid lighting regime was 38.32 kg per m2 compared with 35.04 kg under SON-T. That represents an increase in yield of 9.35%. The average fruit weight was also slightly higher than under SON-T, at 39.2 grams compared with 38.8 grams.

Flexible use

The attractive increase in yield can’t be ascribed solely to the higher light levels in the periods when both systems were in use. The SON-T system was switched off and the CHP unit shut down for maintenance at the beginning of week 19, whereas the LED system was used from 4 am to 7 am for a further three weeks.
“The option to only use the LED lamps either end of the lighting season would be an extra benefit,” Klein says. “Those are often the times when you don’t need the radiated heat produced by the SON-T lamps. LEDs have virtually no impact on the climate. You can always switch them on if you need more grow light. And because they are much more energy-efficient than SON-T lamps, you also have more flexibility when it comes to deciding whether to generate the energy yourself with CHP.”

375 and 600W

Klein is keen to point out that the prototype trialled at Gebroeders Koot was developed exclusively for research purposes. But the lamp has since undergone further development and a commercial 375W version was launched at IPM 2017. All the LEDs are now in one bay and the fitting, which has integrated cooling ribs, can be attached directly to the trellis.
The lamp is called Hyperion 1000 because it has a photon flux of 1000 μmol/s. “Because of the higher uptake of deep red light, it’s the equivalent of a 600W SON-T lamp but it uses 40 percent less electricity,” the cultivation specialist says. “The producer has also recently brought out a more powerful 600W version which is the equivalent of a 1000W SON-T lamp.”

Ten years ago

There is a lot of added value in the new lamp, Koot believes. “It’s efficient, it has a broad spectrum, and its clever design makes it easy to incorporate into an existing system. That will appeal to a lot of growers. I’m also quite impressed. But because of my age and the fact that I have no successor in place, I have decided not to invest in any more grow lights now. If this trial had taken place ten years ago, I would almost certainly have gone for them. But we very much enjoyed taking part in the trial.”


A new type of LED lamp produced in the UK is achieving interesting results. The clever design makes the lamp particularly attractive. It can be attached to the trellis without the use of C profiles and can be integrated into existing 600W SON-T systems with standard connectors. A more powerful version equivalent to a 1000W SON-T lamp was brought out earlier this year.

Text and images: Jan van Staalduinen.


Water treatment system maintains optimum oxygen supply

Water treatment system maintains optimum oxygen supply

Sufficient oxygen in the root environment is a must for a strong, healthy crop. More oxygen makes the crop stronger and boosts production. That’s the experience of Van der Voort Tomaten in Vierpolders in the west of the Netherlands. They use a water treatment system that keeps the oxygen supply in the slab permanently at the optimum level.

Van der Voort grows mini plum and cocktail tomatoes on eight hectares. Three of the eight hectares are artificially lit. This nursery is its second branch: the company, a member of Prominent, has its main site in ‘s-Gravenzande.
Van der Voort bought the Vierpolders nursery a few years ago. The reservoirs there were already aerated with the Agrona Oxybull water treatment system. “It was part of the setup, so we kept using it,” Joost van der Voort explains. “It was only when the system broke down once that we noticed the difference. The roots stopped getting enough oxygen, the crop became less vital and the tops of the plants no longer looked fresh.”

More growth, higher production

The system works with a series of plates lying on the reservoir floor. Air is pumped through a screen containing numerous small membranes, adding millions of minuscule air bubbles into the water. The system is not a massive investment, but according to Van der Voort it is very effective. “The breakdown made us realise just how much added value it delivers. We started off with three units and recently invested in a fourth one. We have also started using the measurements.”
Agrona director Nadir Laaguili explains the importance of sufficient oxygen. “Research has shown that more oxygen in the root environment results in more growth and higher production. A shortage at the roots always and inevitably limits growth.”

Boost for microorganisms

The maximum concentration is ten milligrams per litre. Anything above that is of no use to the plant because the crop doesn’t know what to do with an oversupply. The water can’t retain a larger volume of oxygen either, hence the upper limit of ten milligrams per litre.
According to Laaguili, a higher concentration also improves nutrient uptake. Oxygen is essential for beneficial aerobic bacteria. “If the grower adds extra oxygen in the greenhouse from the day’s supply, they will notice the effects in the crop,” he says. “The plant will be able to feed itself better and the crop will become more vital and grow better. The useful microorganisms in the medium will also receive a boost. So the whole soil food web is strengthened, and that makes for greater plant resilience.”

More and more naturally

Van der Voort uses the water treatment system in combination with AG-Stim from Agrona. This bio-stimulator nourishes and activates the beneficial bacteria present in the soil, accelerating plant nutrient uptake. A side effect of this product is that organic matter is broken down and converted into inorganic material, so the drip lines stay clean. Laaguili: “The volume is very low, but nonetheless: the inorganic material is nutrition for the plant and it is neatly incorporated into the cycle.”
Van der Voort adds: “We no longer need to use chlorine or hydrogen peroxide treatments. And that’s exactly what we are aiming for: to grow more and more naturally with fewer and fewer chemicals. We always used to use ECA water, or electrochemically active water. But that also didn’t fit in with the concept of growing as naturally as possible, so we stopped using it. And chlorine or hydrogen peroxide are also incompatible with growing in a sustainable, natural way because they kill the soil food web.”

Poor supply

Because AG-Stim accelerates nutrient uptake, the grower can set the EC higher, with beneficial consequences for growth, vitality and production.

The product is a perfect fit for a form of horticulture that is geared towards better quality, says Laaguili. “These days, plants only get the four key elements – nitrogen, phosphate, potassium and calcium – and some trace elements. That’s a very poor supply. And it shows: in terms of nutrients and nutritional value, modern conventionally-grown tomatoes are less healthy than organic ones.”
According to the supplier, the product contains 47 important minerals, including essential amino acids. The improvement in plant strength and quality became apparent at the Westland site, where they stopped using it for a while. Van der Voort: “Almost immediately we started getting reactions from the market: ‘Your tomatoes suddenly don’t taste as good. Have you changed something?’”

Checking measurements

The supplier guarantees an optimum oxygen level of 10 mg per litre, providing the water treatment system runs for at least 12 hours every day. The system can be connected to the climate computer. The oxygen concentration is then measured every five minutes, both in the day’s supply and at the drip lines.
The measurements are displayed in a graph and the grower can see at a glance whether everything is going to plan. Van der Voort again: “The measurements enable you to keep an eye on the system. If they indicate that there is insufficient oxygen, there is clearly something wrong in the system. Then you can go and fix the fault. For example, there could be a blockage somewhere, so you will need to flush the pipes.”

Breaking down dirt

But the risk of a breakdown is quite low, both men say. Pumping millions of air bubbles in the reservoir breaks down dirt particles so they don’t become deposited in the pipes. “That works perfectly,” the grower confirms. “We no longer have to clean the silos.”
He is not the only grower using the Oxybull system. The system is installed at about 40 nurseries in the Netherlands, including other companies affiliated to Prominent, 4Evergreen and Red Star Trading. It is also used by growers in Spain and Canada – countries where the company also has branches – including the big tomato producers NatureFresh and Mucci in Canada and Cualin Quality in Spain.


Sufficient oxygen in the root environment is essential for good growth and high production. A water treatment system adds millions of air bubbles into the water supply, producing an oxygen concentration of 10 mg per litre, right at the saturation limit. Van der Voort Tomaten has achieved good results with this system. They use it in combination with a product that has the added effect of keeping the drip lines clean.

Text and images: Jos Bezemer.


Tool for accurately estimating vine tomato crops

Tool for accurately estimating vine tomato crops

The Plantalyzer is a unique tool for accurately estimating vine tomato crops. It counts the number of vine tomatoes on the plant in the greenhouse and provides reliable information for an accurate estimate of the harvest.

The system was developed in close collaboration with Wageningen University & Research. It uses special cameras to measure the bottom two to three leaf-free trusses. The system maps the trusses per stem, the number of fruits per truss and the colour of each fruit. The Plantalyzer thus provides insight into numbers and colour stages. Linking this information to practical greenhouse data produces an accurate estimate of the harvest.


The tool is able to measure large areas of tomatoes, counting both quantity and maturity. The system does that tirelessly every day, always in exactly the same way, and works fully automatically.
Stand number: 11.115


Flemish scientists produce fertiliser from waste flows

Flemish scientists produce fertiliser from waste flows

Bio-engineers from the universities of Antwerp and Ghent have developed a new type of fertiliser based on bacteria derived from food industry waste flows.

In the Flemish food production industry quite a lot of fertilisers, like phosphor and nitrogen, are lost. Attempts have already been made to transform this waste into microalgae, which is apparently very useful as an alternative fertiliser. “Although the results were successful, it was 5 to 10 times as expensive as conventional fertiliser. We have now cultivated and mixed three types of safe microbes; primarily aerobic heterotrophic bacteria, purple bacteria and – to a more limited extent – microalgae”, explains researcher Siegfried Vlaeminck.

Pilot project

Professors at the University of Ghent set up a pilot project to test the mixture on several plant varieties, such as ryegrass, petunias, parsley and tomato plants. “We noticed that the microbial fertilisers works just as well as conventional organic fertiliser, and in some cases even better”, says Vlaeminck. “It may be more expensive, but because microalgae also protect crops against disease, we believe that this will be acceptable for the market.”


Now that the researchers have completed the pilot project, they are looking to scale up the experiment. A few hundred thousand tons will be needed to ensure a cost-efficient production and reliable supply, concludes Vlaeminck. Greenyard Foods has already professed an interest in participating in the experiment.

Source: HLN. Photo: Mario Bentvelsen.


Special packaging material keeps tomatoes fresh for 30 days

Special packaging material keeps tomatoes fresh for 30 days

Researchers at the Indian Institute of Technology (IIT) in Hyderabad have succeeded in keeping tomatoes fresh for 30 days using special food packaging material. A team of two members led by Dr Mudrika Khandelwal developed the food packaging material, which is made from bacterial cellulose impregnated with silver nano particles.

The bacterial cellulose is prepared using Gluconacetobacter xylinus bacteria in order to produce semi-crystalline cellulose nano fibres from a standard substance that contained glucose. “We can use every type of fruit juice that is rich in sugar to produce bacterial cellulose”, explains Dr Khandelwal.

Smaller is better

The nano-sized pores in the bacterial cellulosic matrix restrict the growth of nanoparticles, thus controlling their growth. Dr Khandelwal: “We discovered that if the silver nanoparticles are smaller the antimicrobial activity will be greater.”


To measure the exact antibacterial activity of the bacterial cellulose the material was first tested on isolated bacteria and fungi that occur on rotting tomatoes. The test showed that the bacterial cellulose killed 99% of the bacteria up to 72 hours after the test was initiated. What’s even more remarkable in this experiment is that the food packaging material also demonstrated fungus-combating activity.

Retarding the aging process

Another test revealed that tomatoes wrapped in the bacterial cellulose packaging material remained fresh for up to 30 days when stored at room temperature. Even after 30 days, the tomatoes demonstrated neither wrinkles nor microbial spoilage. Researcher Shivakalyani Adepu indicated that this is because, in addition to the antimicrobial activity, the composite also facilitates a favourable exchange of gases and moisture. “The material ensures that the fruit ages more slowly.”

Other applications

The research team aims to test the food packaging material on exotic fruit to see if the material will also keep this fruit for a longer period of time. Dr Khandelwal says that she would also like to test the same principle on medical products. “The composite can be used as an antimicrobial lining in sanitary napkins and disposable clothing and covering in hospitals.”

Source: The Hindu.