Fruit & Vegetable Magazine

Commercial blueberry production coming soon to northern Canada

Breeders aim to find a mid-high blueberry bush hybrid that is hardy in cold weather.

November 30, 2020  By Madeleine Baerg

An Agriculture and Agri-Food Canada (AAFC) research team in St. John’s, Newfoundland and Labrador is crossing cultivated (highbush) blueberries with their high-in-antioxidants, extremely cold hardy wild (lowbush) cousins in hopes of developing a mid-high hybrid suitable for northern Canadian commercial production.

In late summer and early fall each year, Newfoundland and Labrador locals head outdoors in search of wild blueberries. The berries, prized for their exceptional taste and high level of antioxidants, thrive in the region’s acidic soil despite frigidly cold winters. Unfortunately, the same can’t be said for cultivated blueberries. To date, no commercial blueberry farming has been successful in Newfoundland and Labrador – or, for that matter, many other parts of Canada – because commercial cultivars cannot survive long, harsh winters. That may soon change, thanks to a new effort by AAFC researchers to create cold, hardy hybrids by crossing wild and cultivated blueberries.

Currently, the vast majority of farmed blueberries are highbush varieties. Growing up to eight feet in height, these bushes produce large quantities of big berries, making them ideal for commercial production. However, though cold hardiness varies in different highbush cultivars, none can survive extreme cold (less than -30 C). Wild (lowbush) plants typically grow to only two feet in height. The few that are grown commercially come not from planting consistent genetics but from managing wild, self-propagating, entirely heterogeneous stands. Lowbush berries are small, variable and more perishable than highbush cultivars, but higher in many health promoting attributes, most notably antioxidants. These blueberries are problematic commercially because the bushes produce lower volume than highbush and because no consistent genetics are available.


Michigan State University researcher Stanley Johnson crossed highbush and lowbush varieties during 1950s and 1960s. The resulting half-high bushes have captured some commercial uptake in the northern U.S. but aren’t cold hardy enough to suit northern Canada’s more extreme winters. Agriculture and Agri-Food Canada research scientist, Samir Debnath, decided almost 20 years ago that he would change that.

“In B.C., highbush blueberries grow very well, and they can also be grown in Quebec, Ontario and Nova Scotia. But in Newfoundland, neither highbush nor half-high blueberries developed in the U.S. aren’t well adapted,” Debnath says. “Way back in about 2000, I visited farm fields [in Newfoundland] and saw them trying to grow half-high blueberries. It was a complete failure. It was not profitable and farmers were discouraged. At that time, I thought: if I get the chance, I will develop this. I will develop a hybrid that suits them.”

A dozen years later, he finally captured the funding to begin developing his own mid-bush (half-high crossed with lowbush) hybrids.

In 2013, Debnath and his team started collecting lowbush germplasm from northern Quebec. Then, they crossed those genetics with half-high hybrids developed in the U.S.

“Our intention is to get a mid-height hybrid with high quality and genetic stability that is adapted to this climate,” Debnath says.

But that’s not all. Among his top priorities, he wants yield and fruit size to match highbush varieties. Conversely, he’d like antioxidant levels to match lowbush levels. While antioxidant levels vary from plant to plant in wild populations, lowbush berries range from 20 to 50 per cent (or more) higher than highbush varieties. This combination of priorities could be very difficult: since antioxidants are contained in the skin, increasing fruit size will decrease the berries’ surface to volume ratio, pushing down antioxidant levels.

Typically, developing new blueberry hybrids takes 15 to 20 years due to the slow-growing nature of blueberry bushes: as much as 10 years to develop potential genetics, another three to four years to get fruit from the various cultivars, two more years to achieve stable production, then several years to select the best cultivars. In order to cut that time down to about a dozen years, Debnath employed high technology: a bioreactor system that rapidly grows tiny cultivars at their earliest stages of development, then sugar testing and molecular marking to optimize selection of preferred cultivars. The bioreactor is a sterile, enclosed environment that optimizes nutrition and air, creating ideal growing conditions and protecting plants at their most vulnerable stages from external stressors. Both bioreactor micropropagation and molecular marker analysis are increasingly common in plant breeding and commercial berry crop production.

Seven years into the project, Debnath says he has successfully produced several thousand mid-bush hybrid cultivars. The sheer number of cultivars is daunting but necessary.

“From a seed you get one plant; from one plant you get 10,000 seeds and each one is genetically different,” Debnath explains. “You have to grow many, many plants to find out which genetics are best.”

He turns all viable cultivars over to provincial researchers and several Newfoundland farmers for field trialling.

“We gave 100s and 100s of hybrids because you never know which combinations will work,” Debnath says. “We don’t have the facilities for field testing. And, it’s better if we can have cultivars growing in growers’ field conditions because weaker cultivars will not survive. Ultimately, the best cultivars have to be able to survive in real growing conditions.”

From the many cultivars in field trial, Debnath hopes he and his provincial counterparts will select the best hybrids to develop further. Those will be multiplied using the bioreactor, then field grown again before release to the market.

“We are expecting to bring 10 to 20 cultivars to the market. That’s a good number. Out of these 20, maybe five will be very good.”

He keeps one other priority in mind: diversity.

“From 15,000 plants grown, we will select, say, 15 plants. Those 15 plants will not have every good gene. When we select materials, it means we are eliminating some of the desirable genes. For that reason, part of this project is to retain the genestock in a gene bank for future breeding efforts.”

Newfoundland’s farmers have greeted this work with enthusiasm.

“Growers are very much interested in participating with the field trials,” Debnath says. “We are expecting it will be popular and good for northern climates.”

All materials supplied to growers are provided under a material transplant agreement. Under this agreement, farmers can sell the berries as a heterozygous mixture but cannot propagate the cultivars or make a commercial business from any individual hybrids.

He expects the first semi-commercial production may be possible within the next couple years.

“We won’t have all the answers by then but at least the ones we’ll have will be better than existing ones,” Debnath says.

“Blueberries give farmers the highest farm gate billing in Canada among small crop fruits but even among fruit crops in general. Farmers in northern regions would like to grow blueberries but so far nothing is suitable for them,” says Kevin Schooley, general manager of the Berry Growers of Ontario.

“This is an opportunity for those for whom available varieties can’t survive and be productive,” Schooley adds. “These might best suit fringe areas for farmers who would like to grow blueberries but haven’t had any viable options.”

That said, Schooley says farmers need to consider a start-to-finish business plan before they plant new varieties, no matter how exciting the opportunity.

“You can’t grow something just because you want to grow it. To be successful, you have to look at your own market. Berry growers market their fruit in lots of ways. Before you plant anything, make sure you have a plan for how you’ll sell it.” •

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