Posts Tagged ‘Europe’

Wheat to beat the heat

Adapted from a blog by Jacques Wery, ICARDA Deputy Director General – Research, originally posted on the International Center for Agriculture in the Dry Areas (ICARDA) website.

Land temperature on June 26, 2019. Map generated using information from the Copernicus Sentinel-3’s Sea and Land Surface Temperature Radiometer

Western Europe is in the midst of an intense heat wave that started at the end of June. The southern French commune of Villevieille recorded a temperature of 45.1 °C, breaking the country’s all-time record. The heat also set new temperature records in Germany and the Czech Republic. Other countries like Italy, Spain and Portugal are also gripped with temperatures much higher than normal.

Scientists have attributed the soaring temperatures to the combination of a storm over the Atlantic Ocean and high pressure over central Europe, which is importing hot air from the Sahara. Though heat waves are not uncommon in Europe, this one was unusually early. Experts say climate change is making heat waves more common (Global warming of 1.5 °C IPCC Special Report).

Apart from human health, the heat wave is already causing significant damage in agriculture. Major wheat growers experienced temperatures of 40 °C and higher. This is of great concern, as the heat wave occurred during the crop’s critical growth stages. Wheat is a cool season crop with an optimal daytime growing temperature of 15 °C during the critical reproductive stage. Wheat plants exposed to high temperatures around the period of flowering lose fertility due to pollen dehydration, resulting in less grain formed. It is calculated that for every degree above the optimum 15 °C, wheat experiences a yield reduction of three to four percent.

If a heat wave like such as this one had occurred one month earlier, at the end of May, when Northern European wheat is in full bloom, it could have caused up to 50 percent yield loses, a devastating blow to the European agriculture and food sectors costing billions of Euros.

The response of scientists

Breeding heat tolerant wheat varieties remains one of the most strategic approaches to cope with the risk of unseasonal heat waves. The International Center for Agricultural research in Dry Areas (ICARDA) started in 2012 to use field stations that experience continuous heat-stress to select new wheat cultivars better primed to tolerate this stress.

In Sudan, the experimental farm of Wad Medani was developed together with the Agricultural Research Corporation (ARC) and CIMMYT (International Center for Maize and Wheat Improvement), to test thousands of wheat candidate varieties each year. This station experiences average maximum daily temperatures above 30 °C throughout the growing season, which is less than 100 days long, from planting to harvest. This test was used to identify critical genes controlling heat-tolerant in common wheat, and to release new cultivars of bread wheat and durum wheat capable of withstanding severe heat.

The ICARDA-ISRA durum variety Haby
Senegalese female cooperative growing the ICARDA-ISRA durum variety Haby at above 32 C throughout the season.

Similarly, two heat-stress experimental farms were developed in West Africa to test durum wheat germplasm. In collaboration with Prof Rodomiro Ortiz  of the Swedish University of Agricultural Sciences (SLU) Department of Plant Breeding, the stations of Kaédi in Mauritania and Fanaye in Senegal were upgraded in partnership with the Centre National de Recherche Agronomique et de Développement Agricole (CNRADA) and the Institut Sénégalais de Recherche Agricole (ISRA).

Field testing conducted at these stations – with daily temperatures above 32 °C throughout the cycle and a season of only 90 days – have revealed four new durum wheat cultivars perfectly adapted to tolerate intense heat. The work conducted in West Africa has even resulted in the awarding of the prestigious OLAM Prize for Innovation in Food Security to the team of researchers involved.

To convert this success into cultivars that could be grown, heat tolerance must be combined with the ability to cope with drought stress. An experiment was devised at the Marchouch station in Morocco, where plastic tunnels were placed on the wheat plants at the time of flowering to raise temperatures to above 40 °C and simultaneously prevent any rainfall from reaching the plants.

Plastic tunnels at the ICARDA Marchouch station in Morocco
Plastic tunnels were placed on the wheat plants at the time of flowering at the ICARDA Marchouch station in Morocco

When all other tested varieties lost more than 50 percent yield to the two combined stresses, the ICARDA-INRA (Institut Nationale de la Recherche Agronomique in Morocco) cultivar Faraj lost only 25 percent, a major positive result considering the severity of the stresses tested. Along the same principles, more than 60 wheat varieties of ICARDA origin have been released by national breeding programs in Central and West Asia and North Africa regions and sub- Saharan Africa regions in the last five years alone, thanks to the ability of the germplasm to adapt to some of the most severe wheat stresses occurring around the world.

Can Europe take advantage of success stories?

In the USA and Canada, farmers grow mostly wheat varieties developed and commercialized by public wheat breeding programs. These cultivars have been very popular and public sector wheat-breeding activities are vital to the industry.

In Australia, wheat breeding is conducted by the private sector. However, public researchers are spending the same amount of money on pre-breeding as they did 10 years ago on breeding and variety development together. To take advantage of some of the success stories of ICARDA and CIMMYT, the Australian wheat breeding programs established 10 years ago the CIMMYT-Australia-ICARDA Germplasm Evaluation project (CAIGE). Each year, Australian breeders visit the trials of ICARDA in Morocco and CIMMYT in Mexico. They select the top high yielding wheat genotypes that combine drought and heat tolerance, with other useful traits. These are then imported and tested across Australian sites to confirm the best one for commercialization or use in hybridization programs.

Dr Allan Rattey
Allan Rattey, national early generation wheat breeder with Intergrain/Australia, toured Morocco in April 2019 to witness the performances of ICARDA germplasm in a season that received less than 200 mm of total moisture, equivalent to what most regions of Northern Europe receive in the month of December alone, and with temperatures during flowering regularly exceeding 26 °C.  Dr. Rattey had a chance to select a range of novel genetic material in the form of promising ICARDA lines tested next to popular Australian varieties. 

In Europe, the situation is more like Australia, and public researchers do not work directly on the commercialization and development of varieties, which is left to the private companies. Instead, public research focuses on pre-breeding to develop new breeding techniques and on high-risk, longer-term targets, thereby supporting the private sector and farmers with high-tech innovations.

CGIAR centers such as ICARDA and CIMMYT have worked in close collaboration with European universities and advanced research institutions for a long time to develop and adapt the most novel technologies for pre-breeding. It might also be advantageous for European private sector companies to start taking advantage of CGIAR stress-tolerant wheat varieties and develop a system similar to CAIGE used by Australian breeders. By taking advantage of similar environments in Morocco and  Mediterranean environments in Europe, European breeders can select promising germplasm of tomorrow and provide the continent’s agricultural sector with a practical defense against future heat waves.

Rebuttal letter sets the record straight on crop breeding for climate change resilience

Crop scientists refute the flawed findings of a study questioning climate resilience in modern wheat breeding.

This article by Marcia MacNeil was originally posted on May 28, 2019 on

CIMMYT field workers working on wheat crossing as part of the breeding process. (Photo: CIMMYT)

In early 2019, an article published by European climate researchers in the Proceedings of the National Academy of Science (PNAS) journal questioned the climate resilience of modern wheat varieties. The article suggested that modern wheat varieties showed reduced climate resilience as a direct result of modern breeding methods and practices, a claim that researchers at the International Maize and Wheat Improvement Center (CIMMYT) vehemently rebuke

In a rebuttal letter published in the June issue of PNAS a group of scientists, including CIMMYT’s Susanne Dreisigacker and Sarah Hearne, strongly contradict the finding that breeding has reduced climate resilience in European wheat, citing significant flaws in the authors’ methodology, data analyses and interpretation.

“This article discredits European plant breeders and wheat breeders in general, who have been working over many decades to produce a wide range of regionally adapted, stable varieties which perform well under a broad range of climate change conditions,” said CIMMYT wheat molecular geneticist Susanne Dreisigacker.

Among other flaws, they found a number of omissions and inconsistencies.

  • The article shows a lack of understanding of commonly used terms and principles of breeding theory, criticizing newer wheat varieties for demonstrating a decrease in “climatic response diversity.” Less diversity in wheat response — that is, more stable yields despite the influence of climate change — is a benefit, not a threat, to farmers.
  • The article authors contradict the common knowledge among farmers and plant breeders that new elite wheat varieties are generally more productive than older varieties; new cultivars are only approved if they show added value in direct comparison to existing varieties.
  • The article’s claim of long-term losses of climate resilience in “European wheat” is unsubstantiated. The authors extensively used data from three small countries — the Czech Republic, Denmark and Slovakia — which contribute less than five percent of Europe’s wheat supply. Three of the five most important wheat producers in Europe — Russia, Ukraine and the United Kingdom — were not accounted for in the analysis.
  • The authors failed to report the actual wheat yields in their study, neglected to publish the underlying data with the manuscript and have up to now declined requests to make the data available.

Europe is one of the world’s major wheat producers and threats to its wheat production due to climate change would have serious consequences for world’s food security. Luckily, say the scientists who published the rebuttal letter, this fear is unfounded.

“Wheat producers and bread consumers around the world will be relieved to learn that breeders have not ignored climate change after all,” said letter lead-author Rod Snowdon, from the Department of Plant Breeding at Justus Liebig University of Giessen, Germany.

The full rebuttal letter by 19 international plant breeders, agronomists and scientists, is available on the PNAS site and reprinted in its entirety below.

Reduced response diversity does not negatively impact wheat climate resilience

Kahiluoto et al. (1) assert that climate resilience in European wheat has declined due to current breeding practices. To support this alarming claim, the authors report yield variance data indicating increasingly homogeneous responses to climatic fluctuations in modern wheat cultivars. They evaluated “response diversity,” a measure of responses to environmental change among different species jointly contributing to ecosystem functions (2). We question the suitability of this measure to describe agronomic fitness in single-cultivar wheat cropping systems. Conclusions are made about “long-term trends,” which in fact span data from barely a decade, corresponding to the duration of a single wheat breeding cycle. The authors furthermore acknowledge increasing climate variability during the study period, confounding their analysis of climate response in the same time span.

The underlying data are not published with the manuscript. Thus, the assertion that there is “no inherent trade-off between yield potential and diversity in weather responses” (1) cannot be verified. Inexplicably, the analysis and conclusions ignore absolute yields, which increase over time through breeding (3–6). Furthermore, incompatible data from completely different ecogeographical forms and species of wheat are apparently considered together, and the dataset is strongly biased toward a few small countries with minimal wheat production and narrow agroclimatic gradients.

The study assumes that increased response diversity among different cultivars is associated with yield stability. In contrast, the common, agronomic definition of yield stability refers to the ability of a single cultivar to stably perform well in diverse environments, without excessive responses to fluctuating conditions. Response diversity measures that ignore absolute yield do not support statements about food security or financial returns to farmers.

Cultivar yield potential, stability, and adaptation are enhanced by multienvironment selection over long breeding time frames, encompassing climate fluctuations and a multitude of other relevant environmental variables. Translation to on-farm productivity is promoted by national registration trials and extensive, postregistration regional variety trials in diverse environments. The unsurprising conclusion that planting multiple cultivars enhances overall production stability mirrors longstanding farming recommendations and practice (7). The availability of robust performance data from a broad range of high-performing cultivars enables European farmers to manage their production and income risks.

Kahiluoto et al. (1) speculate about “genetic erosion” of modern cultivars due to a “lack of incentives for breeders to introduce divergent material.” To substantiate these claims, the authors cite inadequate genetic data from non-European durum wheat (8), while explicitly dismissing clearly opposing findings about genetic diversity in European bread wheat (9). Short-term reductions in response diversity in five countries were misleadingly reported as a “long-term decline” in climate resilience in “most European countries,” although six out of seven countries with sufficient data showed no long-term decline. The article from Kahiluoto et al. and the misrepresentation of its results distorts decades of rigorous, successful breeding for yield potential and stability in European wheat and misleads farmers with pronouncements that are not supported by relevant data.


1 H. Kahiluoto et al., Decline in climate resilience of European wheat. Proc. Natl. Acad. Sci. USA 116, 123–128 (2019).

2 T. Elmqvist et al., Response diversity, ecosystem change, and resilience. Front. Ecol. Environ. 1, 488–494 (2003).

3 S. De Schepper, M. De Loose, E. Van Bockstaele, P. Debergh, Ploidy analysis of azalea flower colour sports. Meded. Rijksuniv. Gent. Fak. Landbouwkd. Toegep. Biol. Wet. 66, 447–449 (2001).

4 I. Mackay et al., Reanalyses of the historical series of UK variety trials to quantify the contributions of genetic and environmental factors to trends and variability in yield over time. Theor. Appl. Genet. 122, 225–238 (2011).

5 F. Laidig et al., Breeding progress, environmental variation and correlation of winter wheat yield and quality traits in German official variety trials and on-farm during 1983-2014. Theor. Appl. Genet. 130, 223–245 (2017).

6 T. Würschum, W. L. Leiser, S. M. Langer, M. R. Tucker, C. F. H. Longin, Phenotypic and genetic analysis of spike and kernel characteristics in wheat reveals long-term genetic trends of grain yield components. Theor. Appl. Genet. 131, 2071–2084 (2018).

7 P. Annicchiarico, “Genotype x environment interactions: Challenges and opportunities for plant breeding and cultivar recommendations.” (Food and Agriculture 201 Organisation of the United Nations, Rome, Italy, 2002), FAO Plant Production and Protection Paper 174.

8 F. Henkrar et al., Genetic diversity reduction in improved durum wheat cultivars of Morocco as revealed by microsatellite markers. Sci. Agric. 73, 134–141 (2016).

9 M. van de Wouw, T. van Hintum, C. Kik, R. van Treuren, B. Visser, Genetic diversity trends in twentieth century crop cultivars: A meta analysis. Theor. Appl. Genet. 120, 1241–1252 (2010).

Deadly strain of wheat stem rust disease surfaces in Europe

Scientists have shown that the first appearance of wheat stem rust disease in the U.K. in nearly 60 years, which occurred in 2013, was caused by the same virulent fungal strain responsible for recent wheat stem rust outbreaks in Ethiopia, Denmark, Germany, and Sweden.

Wheat stem rust was reported by the Greeks and Romans, and the latter sacrificed to the gods to avoid disease outbreaks on their wheat crops. Photo: CIMMYT/Petr Kosina

Wheat stem rust was reported by the Greeks and Romans, and the latter sacrificed
to the gods to avoid disease outbreaks on their wheat crops.
Photo: CIMMYT/Petr Kosina

As reported today in Communications Biology, an international team of researchers led by the John Innes Centre, U.K., found that 80 percent of U.K. wheat varieties are susceptible to the deadly stem rust strain. The group also confirmed for the first time in many decades that the stem rust fungus was growing on barberry bush, the pathogen’s alternate host, in the UK.

“This signals the rising threat of stem rust disease for wheat and barley production in Europe,” said Dave Hodson, senior scientist at the International Maize and Wheat Improvement Center (CIMMYT) and co-author on the study.

A scourge of wheat since biblical times, stem rust caused major losses to North American wheat crops in the early 20th century. Stem rust disease was controlled for decades through the use of resistant wheat varieties bred in the 1950s by scientist Norman Borlaug and his colleagues. Widespread adoption of those varieties sparked the Green Revolution of the 1960s and 70s.

In 1999 a new, highly-virulent strain of the stem rust fungus emerged in eastern Africa. Spores of that strain and variants have spread rapidly and are threatening or overcoming the genetic resistance of many currently sown wheat varieties. Scientists worldwide joined forces in the early 2000s to develop new, resistant varieties and to monitor and control outbreaks of stem rust and yellow rust, as part of collaborations such as the Borlaug Global Rust Initiative led by Cornell University.

Barberry is a shrub found throughout the temperate and subtropical regions. Photo: CIMMYT archives

Barberry is a shrub found throughout
the temperate and subtropical regions.
Photo: John Innes Centre

The Communications Biology study shows that 2013 U.K. stem rust strain is related to TKTTF, a fungal race first detected in Turkey that spread across the Middle East and recently into Europe. It was the dominant race in the 2013 stem rust outbreak in Germany and infected 10,000 hectares of wheat in Ethiopia’s breadbasket the same year.

Because disease organisms mutate quickly to overcome crop resistance controlled by single genes, researchers are rushing to identify new resistance genes and to incorporate multiple genes into high-yielding varieties, according to Ravi Singh, CIMMYT wheat scientist who participated in the reported study.

“The greatest hope for achieving durable resistance to rust diseases is to make wheat’s resistance genetically complex, combining several genes and resistance mechanisms,” Singh explained.

Barberry, which serves as a spawning ground for the stem rust fungus, was largely eradicated from the U.K. and U.S. last century, greatly reducing the spread and genetic diversification of rust disease races. Now barberry is being grown again in the U.K. over the last decade, according to Diane G.O. Saunders, John Innes Centre scientist and co-author of the study.

“The late Nobel laureate Norman Borlaug said that the greatest ally of the pathogen is our short memory,” Saunders stated. “We recommend continued, intensive resistance breeding. We would also welcome work with conservationists of endangered, barberry-dependent insect species to ensure that planting of common barberry occurs away from arable land, thus safeguarding European cereals from a large-scale re-emergence of wheat stem rust.”

Click here to read the John Innes Centre media release about the Communications Biology report and view the report.