MSU Researches Growing Seedlings Under LEDs

Figure 1. An experimental plant factory at Osaka Prefecture University in Japan, which is also used as a prototype for commercial growers, utilizes LEDs and fluorescent tubes to produce lettuce.
Figure 1. An experimental plant factory at Osaka Prefecture University in Japan, which is also used as a prototype for commercial growers, utilizes LEDs and fluorescent tubes to produce lettuce.

Light-emitting diodes (LEDs) are of increasing interest among commercial greenhouse growers. They are currently being explored and developed in the horticultural industry for low-intensity photoperiodic lighting applications, as well as for high-intensity lighting.

Low-intensity LED lighting at night can promote flowering in long-day crops and inhibit flowering in short-day plants. High-intensity supplemental lighting in greenhouses increases the daily light integral (DLI), which can increase photosynthesis and thus, plant growth.

LED Technology Is Intriguing But Costly
With their increasing electrical efficiency and potential to deliver specific ratios of light, LED technology provides appealing opportunities for plant production. For example, the light spectrum emitted from LED lamps could be tailored for specific crop stages of production or for desired growth characteristics. In addition, LEDs can be installed closer to plants than conventional lamps because energy consumed that is not converted to light (heat) is separate from the light emitted.

The cost of LEDs is the primary limitation to widespread use in the horticulture industry. In addition, for high-intensity lighting, existing systems cannot be retrofitted with LEDs. The benefits of using supplemental lighting in greenhouses when the DLI is low (<10 mol∙m-2∙d-1)

Other factors to consider with LED lighting include: their efficiency in converting energy into light (µmol∙Watt), availability of rebates from power companies, electricity costs, the intensity and directionality of light, the spectral output and the reputation of the manufacturer. Many of these factors vary considerably among LED manufacturers.

Using LEDs In Plant Factories May Offer Economic Value

In some situations, LED lighting may be economically practical when growing high-value crops, such as microgreens, propagaules or high-wire vegetable crops, especially where land is expensive and electricity costs are high.

To maximize yield per square foot of land, “plant factories” have been emerging in highly populated areas such as Japan (Figure 1). A plant factory is a completely enclosed, air-conditioned plant production facility with multi-tiered shelving and usually with carbon dioxide injection systems. There are an estimated 120 commercial plant factories, mostly in Japan, and most of them currently utilize fluorescent lighting.

The plant factory concept has the potential to alter the way that high-value crops, including plugs, liners and tissue-culture propagules, are grown. Trial projects like the Smart Plant Factory Network in Japan aim to develop a proof-of-concept network between commercial growers and homeowners to produce food crops such as lettuce locally. Other plant factories in Japan and the Netherlands grow microgreens or high-value ornamentals.

While production in plant factories can be much greater than that produced in conventional greenhouses, only a minority of plant factories are reportedly making a profit. However, the economics of LEDs continue to improve and it’s only a matter of time until they will be widely used in crop production.

Research Modules Show How Seedlings Respond To LED Lighting

In 2011, we started a research project with LEDs to investigate the concept of growing young plants under only LED lighting. Our goal was to further understand how the different colors of light influence growth so high-quality young plants could be produced commercially.

Figure 2. LED modules were constructed for research at Michigan State University to investigate how different colors of light influenced growth of bedding plant seedlings. Photo courtesy of Osram Opto Semiconductors.
Figure 2. LED modules were constructed for research at Michigan State University to investigate how different colors of light influenced growth of bedding plant seedlings. Photo courtesy of Osram Opto Semiconductors.

We partnered with Osram Opto Semiconductors to construct six custom LED growth modules (Figure 2), each containing blue, green, orange, red and hyper red LEDs (peak wavelengths of 446, 516, 596, 634 and 664 nm, respectively), which could be independently dimmed to deliver the desired ratios of light. Each module has fan-cooled driver boards that could be moved closer or further away from plants to provide a range of light intensities. The modules were placed in an air-conditioned growth chamber and light intensity and air and plant temperatures were constantly measured using sensors connected to a datalogger.

In a series of experiments we performed, the first examined how plants acclimated to different wavelengths of red light while delivering a constant amount of blue and green light. Red is considered the most efficient light for photosynthesis, but there are different colors of red light and we didn’t know if there was a benefit to delivering one color of red or another, or a blend of two or more reds.

Tomato ‘Early Girl,’ marigold ‘Deep Orange,’ Petunia ‘Wave Pink’ and Impatiens ‘SuperElfin XP Red’ were grown for 31 to 45 days under 160 µmol∙m-2∙s-1 of photosynthetic light under six lighting treatments. The percentages of orange (peak at 596 nm), red (peak at 635 nm) and hyper red (peak 665 nm) were 0-80-0, 0-60-20, 0-40-40, 20-30-30, 0-20-60 and 0-0-80. Ten percent blue and 10 percent green light were delivered in all treatments.

Generally, plants grown under the different colors of red light grew similarly; shoot fresh and dry weight, seedling height and leaf number were usually the same (Figure 3). Tomatoes in all treatments developed edema, or blistering, especially along the veins of the leaves of the seedlings. This has been reported previously in tomato and a few other species in the nightshade family when there is not sufficient blue and/or UV light. Marigold developed purple speckling in all treatments, but otherwise developed normally along with the other plant species.

Figure 3. Impatiens ‘SuperElfin XP Red’ grown at the same light intensity but with different percentages of orange, red and hyper red light from LEDs had similar characteristics after 43 days at 68°F. All treatments also received 10 percent blue light and 10 percent green light.
Figure 3. Impatiens ‘SuperElfin XP Red’ grown at the same light intensity but with different percentages of orange, red and hyper red light from LEDs had similar characteristics after 43 days at 68°F. All treatments also received 10 percent blue light and 10 percent green light.

Since plants grew similarly under different colors of red light, the type of red LEDs to be installed for a horticultural lighting fixture could depend on other factors such as LED longevity, efficiency and cost, without affecting plant quality.

Part two of this article will discuss the results of additional experiments, which focused on the effects of green and blue light on seedling growth and plant architecture.

Editor’s Note: The authors thank Mike Olrich for his technical assistance, funding from Osram Opto Semiconductors, the USDA Floriculture and Research Initiative and private companies that support MSU Floriculture.

Topics: , ,

Leave a Reply

More From Equipment...
Floral Greenhouse at Vineland Research Centre

July 20, 2016

Research And Commercialization Unite At The New Vineland Greenhouse Technology Centre

The new, pre-scale commercial greenhouse facility at Vineland Research and Innovation Centre in Vineland Station, ON, will help accelerate the commercialization of innovative technologies and products coming out of research.

Read More

July 20, 2016

How To Prevent Greenhouse Heating Leaks

Ethylene from malfunctioning greenhouse heaters can lead to crop injury, while carbon monoxide can lead to worker illness. Know the symptoms and how to check greenhouse heaters to avoid these concerns.

Read More
GrowSpan Screen cap

July 18, 2016

Growers Supply Launches GrowSpan Website With New Content And Product Offerings

The GrowSpan website will encompass the brand’s entire greenhouse structure line, and allows growers to quickly browse GrowSpan’s product offerings based on structure type.

Read More
Latest Stories
Harvest Automation HV 100 Feature

May 27, 2016

Harvest Automation Robot Helps You Move Plants Without …

The Harvest Automation HV-100 robot units use lasers and sensors to handle some of the most labor-intensive tasks in the greenhouse.

Read More
HV-100 Robots (Harvest Automation)

May 3, 2016

Harvest Automation Makes Strong Commitment To Greenhous…

The company recently announced it is selling off its robotic warehouse automation business to focus more on providing robotic materials handling to the greenhouse, vegetable, and fruit markets.

Read More
Priva FS Reader

May 2, 2016

What’s New In Greenhouse Environmental Controls

Growers today are looking for systems that save energy, are easy to use, and can be accessed remotely. New products from leading manufacturers are designed to tap into these needs.

Read More
Sentinel In The Greenhouse Feature

April 13, 2016

Monitor Your Greenhouse Conditions Without A Web Connec…

The Sentinel system from Sensaphone provides 24/7 monitoring of temperatures, power outages, and other potential problems, in locations where connectivity is unavailable.

Read More
Philips LED Lunar Greenhouse

March 29, 2016

Philips Lighting And University Of Arizona Study Shows …

A collaboration between Philips And The University of Arizona found that using energy-efficient LED lighting in a prototype lunar greenhouse resulted in an increased amount of high-quality edible lettuce while dramatically improving operational efficiency and use of resources.

Read More
Priva Tomato Deleafing Robot

March 22, 2016

Priva Developing Deleafing Robot For Tomatoes

The deleafing robot, which is designed to mimic the performance of a human while being economically viable, will be tested and evaluated by Dutch growers later this year.

Read More

February 23, 2016

How Light Diffusion Works In The Greenhouse

Ken Aguilar of SolaWrap Films shares how light diffusion technology offers many benefits for greenhouse crops.

Read More

February 22, 2016

New Greenhouse Transplanters Offering More Versatility

New transplanters on the market offer flexibility in speed, plug tray compatibility, and functionality.

Read More

February 20, 2016

Hydrogel Technology Means Growers And Their Customers C…

Water and nutrient management are critical elements for quality plant production in the greenhouse. Maintaining the right amounts of available moisture and fertilizer at all times can be pretty labor intensive, but there are tools available to help you keep these inputs at optimum levels as efficiently as possible. Recently, we visited Evonik Industries’ North Carolina production plant for to see how one of these products — Stockosorb — is made, how it works, and learn the benefits of incorporating these tools in your own operation. Learn more about Evonik Industries’ Stockosorb hydrogel product on the Stockosorb website.  

Read More
Using cables in place of a solid belt, the Echo-Veyor design doesn’t cast shadows, so plants can be grown underneath

February 19, 2016

Echo-Veyor Has Made Plant Handling Easier For Greenhous…

Growers are creating improvements in a range of functions with customized plant handling systems. Several growers have realized efficiencies through customized conveyor solutions, by working with Cherry Creek Systems, based in Colorado Springs, CO, to install its Echo-Veyor cable-driven transport system. Designed to support multiple different tray types and pot sizes, each system is custom-designed for the individual needs of the operation. It can tie into existing posts or be built into a free-standing system.     The Echo-Veyor system has helped growers like Dallas Johnson Greenhouses and Rockwell Farms increase efficiency of product handling in a variety of functions, ultimately reducing time, labor, and labor costs, and improving job functions for employees working on spacing plants, pulling and processing orders, and shipping. Dallas Johnson Greenhouses in Council Bluffs, IA, reduced labor, saved time, improved its team’s performance, and saw improved plant quality at retail after installing its Echo-Veyor shipping […]

Read More
Metrolina Greenhouses keeps a 4-acre barn filled with wood chips, sourced locally from forestry waste and old pallets. The barn can hold a three- to four-week supply of wood chips

February 18, 2016

Metrolina Greenhouses Has Improved Heating Efficiency W…

Sustainability started to become a keyword in the horticulture industry in the late 2000s, when growers began converting their heating systems to greener options to save on energy costs and reduce their impact on the environment. However, there haven’t been many operations that have invested in sustainable solutions on as large of a scale as Metrolina Greenhouses at its Huntersville, NC, headquarters. Six years later, the operation is still fully committed to its biomass heating system and everything it entails.     Metrolina first fired up its Vynke biomass system from Belgium in 2010. The four wood boilers cover 95% of the operation’s heating needs at its 201-acre main location in Huntersville, NC, and Metrolina still maintains its traditional heating systems for back up and to provide flexibility of resources. Wood chips are sourced locally, with the majority from local forestry activities like wood harvesting companies and developers. The other […]

Read More

January 19, 2016

Tips For Cherry-Picking The Right LED Lighting Solution…

If you want to find the right LED lighting solution for your greenhouse, start with these tips from top lighting manufacturers.

Read More
Feature Image Cob 700 (NewLux)

November 28, 2015

15 LED Lighting Solutions For Your Greenhouse

Narrowing in on the right LED lighting product often comes down to considering your specific crop needs and growing requirements to see what works best for your application. Here are 15 LED products to take into account when choosing the right fit for your greenhouse.

Read More

October 27, 2015

How Dallas Johnson Greenhouses Is Simplifying Shipping

Two years ago, Dallas Johnson Greenhouses, a 61-acre operation in Council Bluffs, Iowa, and No. 21 of Greenhouse Grower’s Top 100 Growers, was struggling to get its orders out. With its range of potted annuals, there were so many skus that it was impossible to get enough carts into the shipping greenhouse, and the crew couldn’t get orders processed fast enough. As a result, the operation was consistently pulling orders until midnight every night during the busy shipping season, says President and CEO Todd Johnson. So Johnson got together with Arie Van Wingerden at Cherry Creek Systems to discuss his problem, and what they came up with has changed everything, Johnson says. Inside one of Dallas Johnson Greenhouses’ existing structures, the team installed a shipping system made with Echo-Veyors, the popular cable conveyor system designed by Cherry Creek Systems. The system was placed right in the front of the greenhouse, […]

Read More
Tidal Creek Growers

October 24, 2015

Five Tips For Successful Use Of Boom Irrigation Lightin…

Michigan State University Extension shares five tips to help growers use boom irrigation lighting more effectively to accelerate flowering of long-day ornamental crops.

Read More

October 8, 2015

Industry Standards For Greenhouse Lighting On The Horiz…

As the use of LEDs has risen among greenhouse growers, so have concerns about the best way to measure and compare the many LED light products across the market. As a result, the lighting industry is responding to a call for greater transparency and the development of standardized measuring and testing methods.

Read More

September 28, 2015

11 Products For Precision Greenhouse Growing

These new options in equipment, automation, structures, lighting and software are designed to help growers run their operations with efficiency and accuracy and at a lower cost.

Read More
Laura Drotleff

September 25, 2015

Growers Solve Problems With Precision Horticulture

My dad’s hands are covered with sores, nicks, scratches and bruises. It’s the ongoing reward — or drawback — of his ingenuity, as he’s constantly wrenching on equipment or constructing new innovations that will help him get work done more efficiently on the farm. As a kid, I would always marvel at his toughness, and how he would barely notice a new wound, shrugging it off as he kept working, driven to complete his work and bring his idea to fruition. He’s still at it today, and his hands tell the story of the many projects he’s completed over the years. I’m guessing many of you can relate, and your hands look similar to my dad’s. After all, ingenuity is the name of the game in this business, where creative thinking to solve problems often leads to revolutionary solutions that automate production, save labor and cut costs. That’s easy to […]

Read More
[gravityform id="35" title="false" description="false"]