New Blueberry Growing System Could Help Improve Efficiency

Blueberry TreeAn Oregon State University (OSU) researcher is aiming to lower production costs for growers by creating a new kind of blueberry that develops as a tree instead of the traditional bush.

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Wei Qiang Yang, blueberry agent for the OSU Extension Service, has tested a grafted blueberry “tree” that grows on a single stem on a research plot at OSU’s North Willamette Research and Extension Center in Aurora every year since 2009. Yang is collaborating with researchers who are testing other blueberry varieties grafted onto rootstocks at land grant universities in California and Florida as part of a multi-state effort.

“The first rootstock that will come out of this research for commercial use will significantly change the way blueberries are currently produced and harvested,” says Yang, a horticulture professor in OSU’s College of Agricultural Sciences.

The research could benefit an industry that’s economically important to Oregon. The blueberry industry contributed $107.5 million in sales to Oregon’s economy in 2012, according to a report by USDA and OSU Extension. Growers produced 72 million pounds of blueberries on nearly 8,000 acres.

Growers use machine harvesters with catch plates to collect blueberries, but because blueberry bushes have multiple stems, the catch plate cannot fully encircle each stem of the bush. So growers must bear about a 15% to 25% loss in terms of the fruit that the catch plate misses, according to Yang. But cultivating a blueberry bush in a tree form would change that, he says.

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“This work isn’t just academically important, it’s valuable from a practical standpoint in that it will be very significant for improving machine harvesting efficiency and the adaptability of blueberry plants to different soil conditions,” Yang says. “The wild-grown species is better adapted to nutrient-poor and relatively high-pH soil. If we’re successful, this is going to change the way we raise blueberries.”

Going About Grafting

To make the grafts, Yang started with seeds from a wild-growing blueberry plant known as sparkleberry, which originated in Texas, Oklahoma, and Florida. In the wild, some plants grow on a single stem to heights of up to 10 feet. But the tiny berries are full of seeds and the fruit has a bad taste, Yang said. He then grafted three popular highbush varieties — Liberty, Aurora, and Draper — onto the wild-growing plants. He wanted a blueberry plant that had a similar yield to its domestic cousins and had a good taste.

So far, yields of the grafted plants have compared favorably to their domesticated cousins, with the exception of Liberty. A grafted Liberty plant yielded an average of approximately 1.03 pounds of fruit per single tree, compared to an average of 1.68 pounds per single bush on a domesticated Liberty plant. A grafted Draper plant yielded an average of approximately 0.60 pounds of fruit per single tree, while a domesticated Draper plant yields an average of 0.55 pounds per single bush. A grafted Aurora yielded an average of 1.07 pounds of fruit per single tree, while a domesticated Aurora yields an average of 0.88 pounds of fruit per single bush. Taste has also compared well.

Yang must still analyze results of data collected on fruit quality factors such as firmness, size, and total acidity. This is the first year researchers were able to collect data on yield for the project in Oregon. Yang will investigate future yield projections and machine harvesting potential next. If results continue to show promise, the blueberry tree could be ready for release to nurseries in approximately five years.

Though some people have tried grafting blueberry trees on a small-scale basis in the past, Yang says this is the first major collaborative research effort to graft a blueberry tree that is viable for commercial growers.

Yang receives funding for the research from the Oregon Blueberry Commission and USDA’s Specialty Crops Research Initiative.

Editor’s Note: This story was provided by Oregon State University.

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