research update

Breeding resistance to bruising

It’s an important factor asmore growers turn to machine harvesting. By Judie Steeves


olling a blueberry between your thumb and finger, then gently squeezing it to see when it ‘gives’ is the easiest test for berry firmness, but what’s even more important is a test for tolerance to bruising, explains berry breeder Michael Dossett with B.C. Berry Cultivar Development Inc.

And the bruising test takes days and a sequence of activities much more complex than the field test done with the fingers for firmness. For firmness — a particularly important fruit characteristic today

when many growers are looking for fruit that’s suitable for machine harvesting — there is also a firmness meter that is more scientific than the simple finger-firmness test. However, real fruit quality is determined not just by the

firmness of the berry, but by its resistance to bruising following a similar dropping activity that mimics

JUDIE STEEVES Berry breeder Michael Dossett.

the fall from the berry bush onto the catcher plate of the picking machine, explains Dossett.

The internal damage that causes bruises might not show up immediately, so to test for it, it’s necessary to leave the dropped fruit for a couple of days before cutting each piece in half to see if any bruising shows up. Bruising tolerance can be due to a tougher skin or more-resilient skin, a different cell structure or denser cell structure, says Dossett. “Ultimately, we all need to be aware of the need for high-quality fruit.”

Varieties that growers are using currently are marginally suitable for machine picking, and some shouldn’t really be machine picked, he explains.

MICHAEL DOSSETT Examples of blueberry bruising. 16 British Columbia Berry Grower • Summer 2017

More and more growers are now looking to machine

picking to resolve the many issues with human labour to pick the fields, including the cost, so a fruit variety that reacts favourably to being machine- picked is very desirable today. Sometimes growers can get away with picking varieties such as Duke and Draper with machines, especially if the packer realizes it is machine-picked fruit, and if it isn’t being shipped far from the field.

However, traditional varieties simply weren’t bred for machine picking. Newer varieties now in the pipeline are firmer and more resistant to bruising, he notes.

With 10,000 seedlings a year that he visits weekly, Dossett says it would be impossible for him to perform that bruising test on fruit from every plant, so first he whittles the number of trial plants down by using the firmness test, flavour tests, and even by assessing the plant growth habit.

For machine harvesting, plants should be upright with a narrow crown. A vase-shaped plant with fruit on the edges of the plants instead of hidden inside the bush, is ideal, he explains. And, in the B.C. berry breeding program funded predominantly by industry, Dossett reports they are finding that characteristic.

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