The effects of climate change and increasing abiotic stress on wheat and potato: A discussion with project experts

Jacques Le Gouis works at the French National Research Institute for Agriculture, Food and the Environment (INRAE) in France and he is the Species Leader for bread wheat in SolACE. Pasquale de Vita works at the Council for Agricultural Research and Economics (CREA) in Italy and he is the Species Leader for durum wheat in SolACE. Orsolya Papp works at the Hungarian Research Institute of Organic Agriculture (ÖMKi) in Hungary and she is the Species Leader for potato in SolACE. 

Experts assume that weather will become more variable in the coming years with climate change. What does this mean for wheat and potato?

Increased climatic variability may have large impacts on wheat and potato production and breeding. Climate change produces a cascade of challenges to crop production, for example shifting climate trends, but also more extreme weather events (floods, periods of drought, heat waves, etc.). Jacques Le Gouis gives the example of 2016 in France, Belgium and Switzerland, where a warm winter favoured the development of wheat biomass and viral diseases transmitted by aphids and leafhoppers. Then, a wet spring favoured the development of fungal diseases, lodging and sterility due to a lack of radiation. 

Climate change, “increases the instability of wheat [and potato] production in time and space and reduces the predictability of yields and quality all over the world”, says Pasquale de Vita. 

According to Jacques Le Gouis, this unpredictability “also means it will be much more difficult to breed for adapted varieties as the weather is more variable and each experimental year unique in terms of intensity and combination of stresses”.  

While changes in rainfall patterns present challenges to all crop production, Orsolya Papp highlights that “irrigation is needed for potato growing. More long and dry periods result in an increasing demand/need for irrigation. Another problem during dry spells is the decrease in air moisture to a point where plant stomata have to close in order to lower potential plant water loss”. This increased stress on the plant causes the growth of the potato plants and tubers to slow down.

How well do wheat and potato deal with different stresses, and what are the major weaknesses? 

Bread wheat, Jacques Le Gouis:

“The main stresses due to environmental factors (called abiotic stresses) in the frame of climate change are considered to be drought and high temperatures. Drought may have a very high impact on the number of spikes if occurring early during the growth cycle and on the weight of the grain if occurring later. High temperatures will shorten the growth cycle and possibly impact the number of grains, causing flower sterility, and they will ultimately impact the weight of the grains. Several studies have shown that there are differences between cultivars in the response to these constraints. However, very few studies were conducted in Western Europe, where the tolerance to drought is poorly considered in breeding.”

Durum wheat, Pasquale de Vita:

“Among the winter cereals, durum wheat is one of the most sensitive to abiotic stress. The spread of this species in areas particularly sensitive to climate change, such as those in the Mediterranean basin, further aggravates the effect produced by the rise in temperature and the reduction of precipitation on crop productivity. This new climate scenario also makes it hard to define the new genetic improvement targets for resistance to abiotic stress, as adverse situations (e.g., drought) can occur in different periods of the crop cycle and/or present themselves with different levels of intensity. Recently, in various areas of the Mediterranean basin, drought periods have been frequent even during the early stages of crop development, i.e. during the winter period, when the rainfalls should be more abundant, making the work of breeders even more complex.”

Potato, Orsolya Papp:

“The potatoes can survive with less water, but this results in smaller yields. Therefore, it is in the farmer’s interest to deal with the drought stress. The major issues are the capacity of water resources, dealing with water regulatory authorities, improving the irrigation system, and the lack of drought-resistant varieties.”

How might this impact European wheat and potato production? 

Wheat and potato yields could be impacted negatively, as the continued effects of climate change increase the frequency and intensity of extreme weather phenomena. The level of impact on yields is dependent “on the frequency and intensity with which extreme weather phenomena will occur” says Pasquale de Vita. Relating to impacts on bread wheat yield, Jacques Le Gouis points to a study (Llobell et al., 2011), which “estimated that temperature and precipitation trends observed between 1980 and 2008 decreased wheat yield on average by 5%. It is of course much more difficult to assess the possible impact of extreme years. However, in 2016, bread wheat yield decreased in France by about 30% compared to previous years.”
In addition to reduced yields, Pasquale de Vita highlights the potential “impact on durum wheat grain quality (i.e. protein content and gluten quality).” He also points out that “such climate change may thus cause difficulties regarding the supply to the processing industry, since it will be complex and difficult to make yield and quality forecasts.
Ultimately, investing the resources needed to cope with “these problems results altogether in higher production costs, which affects the European potato [and wheat] production and trade” says Orsolya Papp.

Is it possible to produce wheat and potato varieties that are more resilient to these types of stress? 

Yes, it is possible. There are significant genetic variabilities in both wheat and potato varieties, which can be utilised to produce better-adapted varieties (to both biotic and abiotic stresses). “This is what public research institutions, universities and private companies operating in the seed sector are committed to” says Pasquale de Vita. According to Jacques Le Gouis “This is, however, a long-term process that needs at least ten years from the initial cross to a possible variety available for farmers.” 
“Apart from the genetic base, different microbial inoculants can also help the plants deal with drought. The colonisation of bacteria and mycorrhizal fungi increase the surface of roots, thus increasing the water-absorbing surface. Research on these useful strains is very promising for agricultural production” says Orsolya Papp.

Has SolACE had any success in this regard? 

“Yes, SolACE is a multi-actor project, in which private and public research institutions are involved. It aims to address how to cope with combined abiotic stresses from both a genetic and an agronomic point of view in an effort to provide solutions to farms involved in the production of durum wheat,” bread wheat and potatoes, says Pasquale de Vita.

For bread wheat, Jacques Le Gouis notes: 

“SolACE was successful in characterising the genetic variability for the response to drought by bread wheat lines and hybrids. This was analysed in combination with nitrogen deficiency that is likely to occur in low-input systems. This is especially the case if a dry period occurs when nitrogen fertilisers are applied. SolACE particularly assessed the variability of the architecture of the root system in controlled conditions as this may be a major trait to breed for in dry conditions.”

Regarding durum wheat, Pasquale de Vita says:

"From a genetic point of view, the adoption of high-throughput phenotyping platforms adapted to specific morpho-agronomic traits (i.e. root architecture, nutrient efficiency, yield potential), the identification of genetic materials with peculiar characteristics, and the application of new breeding methods through the use of molecular markers (i.e. genomic selection) will allow seed companies to have new tools available to develop new durum wheat varieties. 

From an agronomic point of view, it is also possible to improve soil fertility through the exploitation of efficient microbial inoculants such as arbuscular mycorrhizal fungi (AMF) and plant growth-promoting bacteria (PGPB). On top of that, adequate crop rotation, and increase in soil organic matter will make the cropping system more environmentally and economically sustainable for durum wheat, offering farmers new tools for crop management and improved resilience to climate change".

For potato, Orsolya Papp says: 

"Solynta, one of the SolACE partners, works with potato breeding. In the frame of the SolACE project, Solynta established several promising lines and variety candidates which are currently being tested in the field in order to determine their productivity. Different microbial inoculants are also being tested for field-grown potatoes, based on other SolACE partners' work."

What can farmers do to protect themselves against these kinds of stresses?

Farmers can limit the potentially harmful impacts of climate change both by using adapted varieties and by adopting relevant agronomic solutions like “the basic principles of conservation agriculture. These principles include longer crop rotations; reduced or no-tillage; cover crop, if applicable, and crop residues management,” says Pasquale de Vita. It is also important to stay informed about expected weather events and trends, as well as integrating “new scientific innovations, including new hybrids and water-saving agricultural techniques” says Orsolya Papp.

Pasquale de Vita also highlighted 

“the interest that numerous farmers have shown in durum wheat genotype mixtures and composite cross populations. The latter resulted from the combination of different durum wheat genotypes still in the segregation phase, which are not stable and can therefore adapt to different cultivation areas and weather conditions. As part of the SolACE project, a network of Italian, French and Hungarian organic farms are participating in the evaluation of these new genetic materials. In this case, the goal will be to provide farms with a ready-to-use tool that might mitigate the impact of global warming, reducing the "risks" in the medium to long term and stabilising farm incomes.”

Reference

Lobell DB, Schlenker W, Costa-Roberts J (2011) Climate trends and global crop production since 1980. Science 333:616-620