Arable
Improving crop resilience in the face of a changing climatic, agronomic and political landscape How are wheat and OSR breeders working to combat the effects of extreme weather events, gradual loss of many key agrochemicals and the need to change farm practices in order to meet Carbon Net Zero targets? Rachel Hicks writes. Over the last few years, a huge reduction in the ag-chem armoury has meant the remaining actives need careful stewardship, with the threat of resistance hanging like a heavy cloud above agronomists and growers alike. Add to this regular and prolonged extreme weather events at the polar ends of the scale, and the pressure to be carbon neutral, and it’s no wonder so many farmers are considering retiring the combine to the shed and selling up. But it’s not all doom and gloom – in fact, there has never before been so much research carried out into the physiology and geneology of cereals and oilseeds; and genetics, including gene editing, are playing a major part in breeding decisions. Studies on how UK crop yields are influenced by weather patterns have indicated that low wheat and OSR yields are associated with wet winters and hot/dull conditions during spring and summer, comments ADAS’ head of crop physiology, Pete Berry (right). “Low OSR yields have also been associated with cold autumn and low minimum temperatures in early spring. Low yields in 2020 have been at least partially attributed to the very dry spring. Pest pressures, such as CSFB, can make crops less resilient to extreme weather. “The association of low yields with wet winters is probably caused by waterlogging, therefore developing varieties that can tolerate these conditions will be important – this is a particular priority for OSR. “Developing varieties with more autumn vigour may also help to establish a robust root system before winter which is more resilient to waterlogging, as well as helping to tolerate any cold autumn conditions. A warmer spring and summer mean that crops require fewer calendar days to pass through their developmental stages, which means there is less time for them to intercept light, photosynthesise and accumulate biomass. Therefore, developing crops which are less sensitive to rising temperatures will be an advantage. “The obvious solution for minimising risk of drought stress is to grow crops with
deeper roots. Soil management should be the first approach considered for improving this, but varieties with faster autumn/spring root growth, and that can penetrate dense soil, will also be important.” ADAS’ technical director – disease and pest management, Faye Ritchie (right), further comments: “Weather will impact disease risk on OSR. Light leaf spot is active and causing damage even when conditions are cold. Warmer conditions are more favourable for phoma stem canker development, with higher temperatures increasing the severity of the disease and leading to early senescence. “There will be pressure for varieties to be resilient against a wide range of threats – however, pathogens tend to evolve and overcome the control measures we use against them. We need to consider not only how to maximise yields but how to protect genetic resistance and consider other strategies that also contribute to reducing disease risk e.g. sowing date.”
Change takes time Of course, developing new, more resistant varieties isn’t an overnight process – but it is one that will ensure the survival of cereal and oilseed crops in the future. As Bill Angus, of Angus Wheat Consultants explains: “Climate change is not new, but the pace of change has accelerated in the last few years. This brings challenges to many crops that we grow globally. Here in the UK, a new winter wheat variety can take anything from seven to 12 years from the original hybridisation to being present in a farmer’s field. “Although our wheat breeding programme (F1 Seed Ltd) selection process is seen by many as somewhat slow, compared to the larger breeders, consistency of performance over a number of challenging years in the field is becoming more critical and thus we test under adverse as well as optimal conditions – stretching the variety’s ability to deliver consistent yields and grain quality. “There is no shortage of genetic variability
– wheat is a global crop – and we therefore pay attention to key physiological traits which are important under our climatic conditions. We are currently working closely with CIMMYT – the largest publicly funded wheat programme on the planet, breeding wheat for 200 million hectares. This organisation is working in extremely challenging environments and, by working together, we can learn from each other about valuable traits to mutual benefit. The freedom to exchange genetic resources is critical for not only the UK but for global food security. In addition, the UK is well served by a strong pre-competitive public research base – something we value in terms of genetic resources but also ‘know how’. “In the longer term, hybrid wheat, which is known for its ability to withstand major environmental challenges, will play a bigger part in growers’ choices. The most critical step will be having a UK-wide testing capability, fit for purpose, which will be able to identify and promote proven reliable varieties.”
Range of challenges Another breeder who continues to put the ability of its varieties to thrive in a range of challenging growing conditions at the heart of its breeding development programme is DSV, comments the company’s Sarah Hawthorne. Improving yield is still very much at the forefront of breeding development work whilst increasing efficiency of nitrogen utilisation and making plants increasingly resilient are some of the many development areas now being focused on, she says. “When it comes to oilseed rape, for example, developing varieties that can better stand up to flea beetle is a definite priority. “But three years of challenging weather across Europe, ranging from dry conditions at sowing to too wet to drill and hot dry weather at flowering to ‘beasts from the east’, have proven just how resilient modern oilseed can be. “Whilst the inherent high vigour of modern hybrids undoubtedly has much to do with this, the breeders’ focus on developing varieties with deep taproots and large branching root architectures has also really come into its own in recent years.” On the wheat front, new DSV Champion has continued over…
10 www.farmersguide.co.uk July 2021
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