Breeding Brassica

Breeding is a long-winded process. Especially when it concerns biennial brassica crops. The time span between idea and commercial product can soon be twenty years or so. Breeding is not a hard science. It is a journey of discovery.
Rijk Zwaan breeding station Fijnaart, The NetherlandsRijk Zwaan breeding station Marne, GermanyAd van den Nieuwenhuizen, head of Brassica breeding at Rijk Zwaan

Quest to find the perfect brassica
The breeding process starts with the wishes from the marketplace. From growers, plant raisers and, increasingly, from the processing industry:

Chain partnerExamples of wishes
Growerdisease resistance, harvestability
Plant raisergermination, uniform plants
Convenience marketsmall florets for broccoli and cauliflower
no discoloration after cutting for cabbage
Consumersattractive product
amounts of healthy compounds (glucosinolates, vitamins)

Breeders follow these developments very closely.

Research accelerates process
Once the wishes are clear, the search is on to find plants with the right characteristics.
Rijk Zwaan has built up a huge collection of genetic material on which the breeders can draw. Crossing plants with usable characteristics can result in progeny which combine the best characteristics.
All Brassica varieties are F1-hybrids. In order to develop a hybrid, we need an inbred mother and father line. A parent line can be made by recurrent self-pollination during 4 to 5 generations. In order to accelerate this process, we use a cell-biological process called microspore culture, to obtain doubled haploids.
Time is also won by using DNA techniques, such as markers. With this technique, any interesting characteristics are ‘marked’, so that it is immediately obvious whether the characteristic is still present after crossings are made.
Crossing cabbage plantsCrossing broccoli plants

Three out of 3,000
Breeders develop thousands of hybrids every year. From 3,000 hybrids, as many as 2,900 have to be discarded in the first year. In the second year another sixty will be found to be unsuitable and in the third year another thirty.
The discarded ones are, for instance, hybrids which have difficulties with seed production; that is a typical stumbling block in Brassica crops. We also take that into account. After six years we are often left with only two or three commercially interesting varieties.
Selection numbers

Commercial introduction
Fortunately, the breeders can look back on many successful introductions. Commercial success is part luck, but it is also based on the knowledge and experience of the breeders. The fact that we have a close-knit team which has been working together for more than twenty years definitely has a positive effect on the result.