Light-emitting diode treatments outperform traditional lighting methods

Jun 23, 2014
This is a photo showing an intercanopy view of the LED tomato experimental setup with ripe fruit at McGill University, Macdonald Campus (Ste-Anne-de-Bellevue, QC). Credit: Mark Lefsrud

In Canada, where outdoor growing seasons are limited, sales from greenhouse fruit and vegetable production operations still surpass $1.1 billion annually. Finding more efficient methods for providing lighting in greenhouse production is a key component to support these high levels of production and increase revenues. "Light irradiance is the limiting factor for increasing production in greenhouses, when all other factors (temperature, nutrient levels, and water availability) are adequately maintained," said the authors of a new study. McGill University researchers Paul Deram, Mark G. Lefsrud, and Valérie Orsat said that the broad-spectrum high-pressure sodium lamps currently used to provide supplemental lighting for greenhouse are "not the most efficient light source" for greenhouse plant production. The team published the findings of their study aimed at finding alternative lighting options in HortScience.

According to the authors, specific light frequencies in the 400- to 700-nm range have previously been shown to affect photosynthesis more directly than other wavelengths (especially in the red and blue ranges). The researchers designed experiments to determine whether light-emitting diodes (LEDs) could reduce lighting costs in greenhouses. "LEDs can be selected to target the wavelengths used by plants, enabling growers to customize the light produced, to enable maximum plant production and limit wavelengths that do not significantly impact plant growth," they explained.

The scientists subjected hydroponically grown tomato plants to three light intensities at three red-to-blue ratio levels. Secondary lighting treatments used for comparison included 100% high-pressure sodium (HPS), 100% red LED light supplied from above the plant, 100% red LED light supplied below the plant, a 50%:50% LED:HPS mixture, and a control (no supplemental lighting). Both runs of the experiment were implemented for 120 days during two (summer-fall and winter-spring) seasons.

Results showed that the five highest number of -producing light treatments were 5:1 high (385 fruit), 5:1 medium (358 fruit), 5:1 low (341 fruit), 19:1 high (315 fruit), and 100% LED (310 fruit). "Overall, the highest producing LED treatments consistently outperformed the high-pressure sodium treatment alone," the authors said. "These treatments can be considered an improvement over traditional HPS lighting for greenhouses."

Outcomes also revealed that high irradiance levels resulted in the highest vegetative biomass and for all ratios. The results showed that the highest biomass production (excluding fruit) occurred using the 19:1 ratio, while higher fruit production was obtained using the 5:1 ratio. The highest marketable fruit production resulted from the 50%:50% LED:HPS treatment. The authors said that the 5:1 high treatment performed well in every category.

"As expected from the literature, higher intensities bring forth more production with all ratios producing more under higher irradiance levels," Deram, Lefsrud, and Orsat said. They also determined that an increase in red increased biomass production and slightly lowered the amount of fruit production. They concluded that LEDs are a "promising mechanism" to enhance artificial lighting systems.

Explore further: Birds 'weigh' peanuts and choose heavier ones

Related Stories

Researchers test effects of LEDs on leaf lettuce

Nov 19, 2013

In the life cycle of plants, most developmental processes are dependent on light. Significant biological processes such as germination, shade avoidance, circadian rhythms, and flower induction are all affected by light. Recent ...

Plants communicate what type of light they want

Apr 08, 2013

Enormous amounts of energy are wasted in greenhouses where our food is grown as a result of the plants receiving too much and the wrong kind of light. This can also stress and damage the plants. Researchers ...

Nitrogen management studied in greenhouse pepper production

Jan 31, 2014

As consumer demand for year-round fresh produce increases, vegetable and fruit producers are facing significant environmental and sustainability issues, and are being challenged to examine traditional production practices ...

Saving greenhouse power with deep-red LED light

Feb 14, 2011

The Siemens subsidiary Osram Opto Semiconductors has developed a powerful light-emitting diode (LED) for use in the cultivation of plants. It emits a deep-red light at a wavelength of 660 nanometers, which ...

Determining biocontainers' carbon footprint

Apr 28, 2014

Many efforts to reduce the environmental impacts associated with commercial horticulture production have failed to influence the general public. For example, one recent study showed that the use of organic fertilizers offered ...

Recommended for you

Birds 'weigh' peanuts and choose heavier ones

3 hours ago

Many animals feed on seeds, acorns or nuts. The common feature of these are that they have shells and there is no direct way to know what's inside. How do the animals know how much and what quality of food ...

Estuaries protect Dungeness crabs from deadly parasites

22 hours ago

Parasitic worms can pose a serious threat to the Dungeness crab, a commercially important fishery species found along the west coast of North America. The worms are thought to have caused or contributed to ...

An evolutionary heads-up—the brain size advantage

23 hours ago

A larger brain brings better cognitive performance. And so it seems only logical that a larger brain would offer a higher survival potential. In the course of evolution, large brains should therefore win ...

Our bond with dogs may go back more than 27,000 years

May 21, 2015

Dogs' special relationship to humans may go back 27,000 to 40,000 years, according to genomic analysis of an ancient Taimyr wolf bone reported in the Cell Press journal Current Biology on May 21. Earlier genome ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.