Breeding and Isolating Brassicas

Posted on Thursday, 6 May 2021 under Stories

Our coastal climate favours these cool-season loving plants. Last year we grew a number of brassicas including broccoli, kale, cabbage, romanesco, and collards from the same variety of plant. This means we have had to undertake measures to avoid cross-pollination this growing season.

All of these brassica crops were originally bred from wild mustard through selective breeding to enhance certain traits. For instance, broccoli was bred for its many flower buds while kale was bred for its large leaves. Since all our brassica crops were bred from the same plant they have the potential to crossbreed with one another. Over this past month we have isolated all of these brassica crops before they flower.

We started isolating our prized breeding project, White Winter Kale Sprouts, which is a cross of a brussel sprout and kale plant. As a breeding population, it is very diverse so we did some intense selective breeding. Our team chose white and purple plants with frilly leaves, roguing any that were fully green or had flat leaves. Roguing is the process of removing inferior or off-type plants.

cabbage and flowering kale close-up

Cabbage left and flowering kale right.

We set up an isolation tent in our entrance garden and transplanted all of our selected plants. Isolation tents are a great tool for seed farmers when it is not possible to achieve adequate isolation distances. Flies are introduced to the isolation tent to carry out pollination; they can be purchased or raised. Check out this video on Youtube if you are interested in trying to capture your own flies.

After our White Winter Kale Sprouts were isolated, we set up caterpillar hoops with mesh netting over our Winter Rainbow Kale and our Dazzling Blue Kale. An alternative to introducing flies within isolation tents is alternate day caging. This technique involves alternating the opening of isolation tents on different days. This process allows insects to pollinate only one of the varieties of the same species at a time while the other remains covered and protected.

Our team continues to work on a number of exciting projects this season as part of our BC Seed Security Program. Check out our latest events and Farm updates for more information on seed saving and breeding.

close-up of kale

Purple and white coloured plants have been chosen over fully green ones.

Extra Resources

Isolation Methods for Seed Saving – Seed Savers Exchange
Seed Works – Brassica Seed: Cleaning – Video by FarmFolk CityFolk
Seed Works – Kale Seed;breeding and selecting – Video by FarmFolk CityFolk