Growing tomatoes with greater energy efficiency is possible

Earlier this week, Philips and Grodan presented the results of their research into energy-efficient tomato cultivation. They used insights from 2023 and 2024 in this year's experiment to demonstrate how energy-saving methods can help plant growth and fruit quality. The 2024-2025 trial concentrated on techniques like adjusting LED light spectra, using advanced energy screens, monitoring vertical plant temperature, and managing water and nutrient intake.

Interesting stuff indeed, and especially useful in a time when energy savings are at the forefront of growers' minds. And, after having seen the presentation of the trial results, it is clear that there are benefits to growing with greater energy efficiency.

View the photo report here.

© Annet Breure | HortiDaily.com
Ruud Kaarsemaker

During his presentation, Ruud Kaarsemaker, a project leader at Normec, demonstrated how different nutrients in water affect whether a crop is more generative or vegetative. He also highlighted how nutrients influence fruit quality and the dry matter content in leaves. He shared some key insights, such as how limited potassium uptake can increase the brix value while decreasing fruit weight, as well as explaining that a lower electrical conductivity (EC) reduces the brix value but increases fruit weight.

Following Ruud's presentation, there was a lot of interaction and discussion in the room about the topic, so there is perhaps still room for improvement in this area.

© Annet Breure | HortiDaily.com
Martin van der Hout (Consulting Engineer), Dennis van Wingerden (Looye Kwekers), Erik Stappers (Horti-Consult), Stijn Jochems (Plant Empowerment) and Lucas Aertsen (Den Berk Délice)

The panel discussion focused on a holistic approach to energy-efficient tomato cultivation, specifically about trying to find balance in the greenhouse and in the crop.

It is advised to be cautious when adjusting settings to save energy, as crops can react quickly. Intense reactions can be more harmful than beneficial.

Marcel Raats from Philips discussed how they achieved energy savings by using the dimming function on lights, occasionally turning off channels entirely, and carefully analyzing the light spectrum. "In this trial, the aim wasn't to compromise on fruit quality, and we can share happily that we succeeded."

Interestingly, LED lighting isn't the only area where savings can be made. The research suggests even more possibilities. Erik Stappers from Horti-Consult, who was closely involved in the test during his time at Philips, continues to monitor it. He noted, "The test pushed energy savings to the extreme, but the crop still thrived. It was extreme, but perhaps we could have pushed it even further."

Many myths were debunked during the presentation.

Is a percentage of drain water a goal? Andrew Lee Grodan shakes his head: "No, certainly not. Drain is a consequence of the cultivation strategy. It is very precise." Lucas Aertsen, Den Berk Délice, agrees. At their company, a fixed percentage of drain is not a topic of conversation. They take EC values into account. And they monitor it very well in the drain water. EC is also measured daily at Looye Kwekers. As is Ph, by the way.

Andrew Lee from Grodan disagrees with the idea of targeting a specific percentage of drain water, stating, "Drain water is a consequence of the cultivation strategy, making it a delicate matter." Lucas Aertsen from Den Berk Délice concurs, noting that a fixed percentage of drain water isn't a focus for them. Instead, they closely monitor EC values in the drain water. Similarly, at Looye Kwekers, they measure EC daily, along with pH levels.

Water uptake itself isn't the main focus. Erik Stappers emphasizes that the key is understanding what nutrients are in the water. "The composition of the drip water is what really impacts fruit quality."

There's a common misconception that dehumidification is costly, but that's not the case when using a heat exchanger. Martin van der Hout, a consulting engineer, explains: "The possibility of dehumidification means that we can compare greenhouse horticulture with Formula 1 racing. Dehumidification is crucial in semi-closed greenhouses. You can keep windows (and screens) closed so as not to waste energy. It would be fantastic if you could harvest the cold and the heat to use at a later time. Then you would really be Max Verstappen."

Stijn Jochems from Plant Empowerment points out potential issues with dehumidification. "Excessive humidity is our enemy. Often, solving one moisture problem leads to another, so it's important to carefully choose the right type of dehumidification method for each specific issue, as not all methods are suitable for every problem."

Tiemo Bodemann from Ridder debunked the myth that reducing energy input delays crop growth. "That's not true. With the right screens and screen strategies, we don't observe such delays. It's important to seek advice on the best approach to manage this."

Stijn Jochems: "In other words, to continue the metaphor: you can have a Formula 1 race car, but if you can't steer and don't know how to operate the thing, it's not going to work. It's about the finesse."

Much was said and much was learned during the presentation. Andrew Lee, Grodan, and Marcel Raats, Philips, summarized it briefly.

The holistic approach of this trial resulted in improved crop performance and stability. By using a dynamic spectrum, they achieved a 2% energy savings. To better manage the crops, various feeding and watering strategies were implemented. The data showed that it's possible to use less energy while achieving higher crop productivity per square meter, along with increased brix value and fruit weight.

As the trial continues, we will keep you informed of all new developments.

View the photo report here.

For more information:
Grodan
Andrew Lee
andrew.lee@grodan.com
https://www.grodan.com/nl/

Philips
Marcel Raats
Marcel.raats@signify.com
https://www.lighting.philips.nl/