Greenhouse Canada

Alberta report: new research and industry update

Insights from Lethbridge study applicable to greenhouse growers across Canada

July 4, 2023  By Treena Hein

Lethbridge College’s 10,000 square-foot, on-campus research greenhouse. Photo: Lethbridge College

A collaborative project conducted by scientists at Lethbridge College’s Centre for Applied Research, Innovation and Entrepreneurship and an industry partner has revealed some useful results for Canada’s greenhouse industry, some of which will be investigated further. The study was funded by the provincial ‘Results Driven Agriculture Research’ program. 

The experiments were run in exacting typical commercial greenhouse conditions in terms of scale, environmental conditions and control, crop density and other production aspect. The team evaluated the performance of seven strawberry varieties and 16 tomato varieties, but results about varietal differences are proprietary to the industry partner. It can be shared that an increase in strawberry plant density (10 plants instead of eight per linear metre) did not result in a significantly higher yield per square-metre.

The trials took place at the college’s greenhouse research complex in Brooks, Alta. which has poly and glass greenhouses side by side. This facility was built through extensive consultation with commercial greenhouse operators from various parts of Alberta about 12 years ago – a time when the industry was using almost all poly.


But in the early days of Alberta’s greenhouse industry several decades ago, companies all started with low, glass greenhouses, explains study lead Dr. Nick Savidov. A few of these original glass houses in Central Alberta are still used for seasonal production of potted plants.

“However, heat loss was really high, so the industry basically switched entirely to double-poly commercial greenhouse later on,” Savidov said. “But then the varieties got better and the poorer light conditions of double-poly was holding the industry back. So, over the last ten years, many growers built new considerably taller glass greenhouses, mainly for year-round vegetable production.”  

Savidov adds that over the last few years, there’s been a lot of consolidation in Alberta’s greenhouse sector, which continues today. 

The Government of Canada report ‘Statistical Overview of the Canadian Greenhouse Vegetable Industry, 2019’ shows that greenhouse businesses across the Prairie Provinces went from 100 in 2015 to 94 in in 2019. In Alberta over that same time period, harvested area significantly increased from 544,222 sq.-m to 741,985 sq.-m.

Returning to the study, as expected, both tomatoes and strawberries performed better in the glass greenhouse. 

“It’s not a surprise that varieties, especially the high-yielding varieties, perform better under glass because there’s more light,” said Savidov, “but for a long time I’ve wanted to provide the evidence for the industry on that. We can definitively say now that glass ROI is swift. The tomato varieties yielded up to 47 per cent higher in glass, with ‘tomatoes on the vine’ type the highest performer. For strawberries, it was up to 36 per cent.”

Other results
The team also tested three grow media, rockwool, coconut fibre and black carbon or charcoal, a pyrolyzed organic material also referred as a ‘biochar.’ It’s a new medium which has exceptional stability compared to rockwool and coconut fibre and also high air porosity and water-holding capacity. 

Savidov started developing biochar as a soilless grow medium about 20 years ago in collaboration with Alberta Research Council (now InnoTech Alberta). He demonstrated that, differently from existing grow media, biochar carbon can be used multiple times. This new study also confirmed what he and others have previously found: that there’s no difference in yield when biochar is used.   

The powdery mildew part of the trial showed higher efficacy for sulfur (Kumulus, BASF), Polyoxin D Zinc salt (Affirm, Nufarm), Fluopyram (Luna Privilege, Bayer CropScience Inc.) and potassium bicarbonate (Millstop). Next effective was UV light and next, two microbial products: Bacillus amyloliquefaciens (Double Nickel, Certis Biologicals) and Streptomyces lydicus (Actinovate, Novozymes). 

These results confirmed what is already known, except for the result of the two microbial products, which needs to be put into context. Savidov explains that the effect of biological products “is not fast, but they work, they are more proactive, and growers should not take the results of our study as a reason to disregard biological products. More research is needed. We want as a industry to minimize chemicals in food production and so it’s important to continue to research biologicals.”  

Starting in the Fall, researchers at Lethbridge College will commence a three-year project that will assess the performance of various crops under different types of lighting.
Photo: Olga Seifutdinova/Getty

Light results
Plant performance was compared in this study under common ‘High Bay’ full-spectrum industrial LEDs, ‘horticultural’ LEDs and HPS. The replicated study was conducted with greenhouse strawberry using Randomized Block Design, with blocks consisting of 100 sq.-m research bays. The target irradiation level was 300 μmol m¯21 PPFD at the crop canopy height. 

Savidov explains that a few years ago, LED manufacturers created specialized ‘horticultural’ lights for the niche greenhouse market, saying that they produce more yield and improve other aspects of plant performance. “They were, and still are, very expensive,” he says, “but our preliminary and limited results in this study show that the High Bay lights also work very well and cost significantly less.”

The 500 W High Bay LEDs also produced higher level of Photosynthetically Active Radiation, PAR, than 1-KW HPS due to their more concentrated one-directional light. 

“Overall, the High Bay lights are pretty high-intensity and produce a full spectrum of warm/cool light,” Savidov notes. “Various light firms have been promoting monochromatic light but full-spectrum is fine. Plants are so adaptable and flexible and take what they need from full-spectrum light.”  

Further study of these light types at Lethbridge College will be conducted through a new three-year project, announced in late April and to start this fall. It’s the first major project in the college’s new 10,000 square-foot research greenhouse (the Centre for Sustainable Food Production). In order to produce meaningful results for the industry, a unique setup has been designed for this project, which will allow to compare different light sources and to do a robust statistical study in the conditions maximally close to those found in a commercial greenhouse facility.

Performance of cucumbers, tomatoes and peppers will be analyzed under horticultural LEDs, High Bay LEDs and conventional High-Intensity Discharge (HID) lights.

“With this information, industry can decide how to evolve their business with more efficiency and with less risk,” says Savidov. “The project will be holistic in its approach, by measuring not just crop productivity and financial benefit, but also power consumption, setup and maintenance costs for different lighting options. This will provide industry with a full ROI analysis that is appropriate to Canadian conditions.”

While the project will focus on measuring yield, quality and ROI, it will also measure plant stress using a sophisticated crop electrophysiology system. This technology will allow growers to detect even minor plant stress at earlier stages before they lose yield, playing a more proactive role in eliminating plant stress.

What else is ahead
Savidov is also continuing his aquaponics greenhouse systems research. 

“They are the future,” he says. “Aquaponics is an amazing opportunity to use so many nutrients that are otherwise lost. Instead of manufacturing and purchasing nutrients, we can get the same ones from fish waste or other sources, such as chicken manure or food waste. And fish are the best of all livestock types in converting feed to weight gain, to high-quality protein. We have just finished a state-of-the-art aquaponics research facility, the largest in Canada and one of the largest in the world, so stay tuned for many research results from there in future.”  

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