A central part of managing commercial greenhouses is to continually improve crop quality and optimize production to meet market demands. Horticultural technology offers a great variety of opportunities to develop production methods and produce. In recent years, there has been an increasing demand for lettuce and herbs that not only taste well, but look decorative too. One solution to meet this demand is with LED grow lighting.   

Swedish-based greenhouse Spisa Smaker AB has experienced this demand first-hand. Being Europe’s largest producer of growing herbs and lettuce, they must constantly develop their business and follow external environments. Therefore, they decided to invest in the HL300 LED grow light solution from OSRAM/Senmatic to increase production quality and energy savings..

“The high controllability of the LED system was a big part of the decision, because we had a great opportunity to work with the pigment of our lettuce to grow the best possible crop. Besides the red pigment of the lettuce, we’ve also been able to produce a more steady crop with a higher density due to the LED system”, says Adam Johnsson, Maintenance Manager at Spisa Smaker AB.

Inducing red pigmentation in lettuce

Several cultivars of lettuce contain red pigment. Under natural lighting conditions, producing red lettuce is possible throughout the summer period, when the concentration of sunlight is high, whereas production is difficult during the shorter, darker days of winter. This was also a primary motivation for installing LED lighting at Spisa Smaker AB.

“We had some quite serious issues with the colour of the red lettuce during winter time and could not provide the quality that was needed”, says Adam Johnsson. “Now, we can grow red pigmented lettuce in winter time with no such issues.”

For years, the general conviction was that the red colour in lettuce was induced by the red light in the sun’s rays. “Now, however, we know that the red pigmentation is caused by exposure to light in the blue end of the spectrum”, says Johnny Rasmussen, Key Account Manager at Senmatic.

This was discovered by exposing the lettuce with LED lights with a high level of blue. “The blue light triggers the red pigment, which in return responds faster than with traditional light sources. This means that cultivars of lettuce that contain red pigment can turn red in only five days under LED light bars”, Johnny Rasmussen explains.

Controlling structure and color with LED lights

As Spisa Smaker AB experienced, the full spectrum LED does not only affect the red color, but also the structure of the lettuce. Whereas blue light creates a compact structure, red light makes the cells of the lettuce stretch.

“The controllability of LED lighting systems enable our customers to improve the quality of their lettuce – essentially growing better produce, says Johnny Rasmussen, adding that a good rule of thumb is to primarily expose the lettuce to blue light in the beginning of the production process. This creates a denser lettuce which increases stability at the roots.”

“Exposing the lettuce to more red light later in the process stimulates growth and increases length in the top of the lettuce. At the final stage of production, blue light should be dominant to induce the red colour”, Johnny Rasmussen elaborates.

Quality and savings

At Spisa Smaker AB, they did not only see significant results in product quality, but also incredible results in electricity savings due to the energy efficient LED fixtures. “When the HL300 system was used at the same intensity as conventional HPS lighting, it generated electricity savings of 48%”, Adam Johnsson explains.

The use of LED lighting in commercial greenhouses is still a new practice, and one that is evolving rapidly as the benefits become evident to more and more people in the industry. “Research is developing fast. In a few years, we will have even more knowledge – and even stronger cases and examples of businesses that have created impressive results, boosting and improving their production output significantly”, Johnny Rasmussen predicts. He believes that making the shift to LED can be key to staying competitive as well as maintaining or gaining larger market shares. “More than ever before, it is vital to be able to adjust production and adapt to external developments in the industry. This is possible with LED lighting due to its unparalleled controllability. Thus, installation of an LED lighting system is not simply an interim solution for quality optimization but an investment in the future.”

OSRAM Ltd./Ltée
www.osram.us/horticulture

Senmatic
www.senmatic.com

The ZELION HL300 Grow Light is a 100- to 600-watt dimmable and spectra-tunable LED horticulture light fixture. It is designed to meet the plant spectra needs for optimum photosynthesis and energy efficiency resulting in faster growth and increased yields.

The ZELION HL300 Sunlight is a 100- to 600-watt dimmable and spectra-tunable LED horticulture light fixture recommended for growth chamber applications where natural light is important or for supplemental lighting where color recognition is important, i.e., in a garden centers. To accommodate an increasing demand from a variety of users, including plant researchers, growers and garden centers, a spectrum was designed to closely match natural sunlight.

The ZELION HL300 Grow White is a 100- to 600-watt dimmable and spectra-tunable LED horticulture light fixture designed for horticulture applications. It is designed to meet the special lighting requirements of growers.
The Grow White has a combination of the ZELION Grow Light and Sunlight fixtures’ spectrum. This spectrum is used in growth chambers where a higher photosynthetic activity is required or by growers requiring supplemental light where color recognition and rapid, healthy growth are key factors.

All of the fixtures in the ZELION HL300 series emit light in the photosynthetically active region (400–700 nanometers) of the visible light spectrum. Their optimized design makes the lights easy to install and they provide the smallest shadow footprint compared to similar class LED fixtures. The lights are designed to withstand crop production environments.