The Dutch are global leaders in greenhouse horticulture, so it makes sense that Leo Marcelis, professor in horticulture and product physiology at Wageningen University in The Netherlands is advocating the introduction of LED lighting in an effort to reduce energy consumption in the greenhouse horticulture sector.
The increasing global demand for highly-controlled production will result in an increase in greenhouse cultivation. Thus, Marcelis believes the sector needs to become more sustainable. Energy consumption in the Dutch horticulture sector is very high and is in fact responsible for 10% of the national gas consumption. Energy costs account for 15–30% of the total costs for a horticultural farm.
More so than heat production, the energy needed for lighting, the driving force behind plant growth, is the issue. “The latest LEDs are about 25% more efficient in converting electricity into light compared to high-pressure sodium lamps, which are commonly used in greenhouse horticulture,” says Marcelis, who also conveys that LEDs open up opportunities for enabling the plants to use the light more efficiently. “We expect that this can be again about 25% improvement, resulting in a total of 50% improvement of the use of electricity for plant growth.”
The scientist can bring about a more efficient use of LED light by plants by choosing the ideal light spectrum for a plant, for example. “Spectrum affects a whole range of plant processes,” the horticulture expert at Wageningen says. For instance, spectrum affects the morphology of plants, which in return can affect the amount of light intercepted by the plants, and hence can also affect the photosynthesis of the plants. According to Marcelis, high-pressure sodium lamps can only be placed above the crop, while LEDs can also be placed in between the crop canopy. “In this way the light can be better distributed over the different leaves,” he says. Another advantage of LEDs can be that they produce no heat radiation. “Due to these improvements of light use by plants, we can grow them with less light and hence save energy.”
Challenges associated with increased use of LED lighting in greenhouse horticulture still have to be overcome, and Marcelis and his colleagues are working on that. “If we really want to make use of all the benefits of LEDs, we need a thorough understanding of the plant responses to the different aspects of light,” the professor says. “Here, we have to realise that in the plant there are many feedback mechanisms and plant responses to light show many interactions with other growth conditions and developmental stage of plants.” His next step in this research endevour is to investigate the different responses in an integrated way.
Written by Sandra Henderson, Research Editor Novus Light Technologies Today
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