Farmers Guide visited Bayer’s expanded Dekalb breeding centre in Boissay, France to look into the next potential varieties both close to market and available for 2019. Heather Briggs reports.
Strong, fast establishment and resistance to diseases and pod shatter are key characteristics Dekalb OSR breeder Matthew Clarke is looking for in his work developing a pipeline of robust, high performance hybrids.
Weather – too wet or too dry – can make growing the crop challenging, with pests like pigeons and slugs making it more so. And, since the banning of neonicotinoid seed treatments, there is also the devastating effect of cabbage stem flea beetle (CSFB) to consider.
“The crops that do best under all these situations are invariably those that are quick to get away,” said Mr Clarke. “Vigorous establishment and very rapid spring and autumn development have become even more important in countering the threat of CSFB.”
Recent work at Trumpington (Cambridgeshire) on Dekalb trials badly infested with flea beetle showed the fastest developing hybrids in both the autumn and spring are better able to tolerate damage from both adult beetles and larvae, he reported.
“Varieties like DK Expedient stood out,” he said, adding that its speed of development is similar to Excalibur, making it an ideal choice if drilling is delayed or has to be done in less than ideal conditions as well as for the main drilling window.
“However, if earlier sown on particularly fertile sites, its very rapid autumn growth habit means an autumn PGR may be valuable.”
He went on to note that varieties with the Clearfield herbicide resistance trait are also fast autumn developers.
“Both DK Impressario CL and DK Imperial CL have shown themselves to be especially rapid in their early growth.
“In addition, there have been no rejections for erucic acid issues with either of them.”
Erucic acid levels can be problematic for crushers, and the current maximum level in most contracts is set to 2 per cent, with a soon-to-be-reduced legal limit of 5 per cent. Over the past three years, higher than expected levels have been found in many double-low crops, with some deliveries incurring significant penalties.
As the Clearfield system ensures control of previous (non-CL) volunteers, it is especially valuable when HEAR varieties have been grown in the rotation, he explained.
“Growers using our Clearfield varieties can take advantage of our free oil quality check at harvest.
“This uses the most accurate gas chromatography to provide them with the best possible pre-delivery assurance on erucic acid content.”
The most promising standard hybrid coming forward from Dekalb this season is undoubtedly DK Exstar, he added.
The first mainstream variety to be rated 8 or better for phoma, light leaf spot and lodging resistance in official testing, Mr Clarke considers it the most complete variety he has ever bred. As it has also been shown to be high yielding in company trials across the UK, he expects it to become extremely popular.
He also highlighted the potential of DK Exsteel, which has similar characteristics to DK Exstar but a slightly different growth habit. Alongside already widely-grown, DK Expansion, it joins the Recommended List for 2019/20.
“DK Exsteel shares an ultra-rapid autumn development habit with DK Extrovert and DK Expedient.
“DK Exstar and DK Expansion, on the other hand, are more akin to DK Exalte and DK Exclaim in their early leaf development.
“Slightly later into stem extension and flowering than the earliest varieties, they are both very rapid in their spring growth. In addition, they all carry our vigorous establishment, double phoma and pod shatter resistance traits.”
Moreover, he revealed, Delkalb is piloting an innovative support scheme with DK Exstar to share the financial risk of establishment with growers, which is expected to further add to its attraction.
The recently-named DK Extremus is another of Matthew Clarke’s favourites – mainly for the yield predictability it has shown in trials across Europe. Like DK Exsteel, however, there will be limited seed available for 2019 planting.
The pace of improvement
Following the merger between Monsanto and Bayer, the pace of all-round winter OSR variety breeding has been stepped-up through the more sophisticated use and application of DNA information at Dekalb’s European breeding centre in Boissay.
Bayer now has the leading hybrid on the RL with a UK Recommendation, the leading hybrid on the RL with a North Recommendation and the only HOLL quality hybrid on the RL, pointed out Mr Clarke.
Better technology for collecting genetic information and increased data processing capacity is helping to speed-up breeding progress with performance information from field trials as well as breeding trials correlated more accurately with environmental conditions.
As a result, Dekalb oilseed rape varieties are now being purpose-built for specific regions with far better focused and more rapid progress targeted in traits like yield and stress tolerance, he said.
“Until now, progress in improving these complex traits has been limited by the fact that they are governed by many genes, each with a relatively small effect.
“This makes them far less responsive to traditional marker-assisted selection than those controlled by major genes.
“We have always known too that some parental combinations have a ‘magic’ factor that makes really good hybrids, whereas others do not work nearly as well, even though they have the same major trait combinations.
“Employing genome-wide selection, we are now profiling our most successful hybrids so we can identify blocks of genes in our parent lines and estimate their breeding value with considerable accuracy. This is effectively turning traditional breeding on its head.”
Alongside this approach Mr Clarke stressed that marker-assisted selection will continue to be an important means of introducing new traits into the Dekalb portfolio.
“We have high yielding varieties with our complete package of traits plus resistance to turnip yellows (TuYV) in the immediate pipeline, as well as Clearfield varieties with club root resistance,” he pointed out.
“We are also tracking big differences in both tolerance and resistance to verticillium wilt in our varieties. Drought tolerance is another area where we see significant variation we can take advantage of, although this is not a priority objective in our programme at the moment.”
Alongside genome-wide selection, much wider use of advanced techniques like di-haploid breeding to ensure maximum parental purity and environment-controlled glasshouses to achieve two generations per year at the Boissay breeding centre are reducing the time taken to develop new varieties.
“Our driving force is producing robust varieties that deliver continual improvements in all-round strength for growers rather than improvements in particular areas at the expense of others.
“With our expanded facilities and the extra opportunities the very latest DNA-based breeding approaches provide, it is a very exciting time to be in oilseed rape breeding.”