Project seeks to improve tolerance of tomatoes to climate change
In recent years, tomato cultivation has been facing a triple problem: firstly, the availability of water is gradually reduced, given the lower rainfall due to climate change (California, Italy, etc.); secondly, the availability of fertilizers is also reduced because of the rising costs of these products and the stricter restrictions on their use due to their impact on water quality and the environment; and thirdly, the genetic diversity of tomatoes for cultivation is limited. All of this has led to a situation in which the environmental and economic sustainability of tomato growing strategies is at risk.
More than 70 percent of the planet's fresh water is used for agriculture, and the IPCC (the Intergovernmental Panel on Climate Change) warns of a greater risk of droughts, which in certain regions may limit the local production of certain foods. The problem of water scarcity coincides with the pollution of water resources; fertilizers and pesticides are affecting its quality and the environmental cost to pay is very high.
Getting more food per drop of water is a challenge, which goes beyond optimising irrigation systems; it requires an interdisciplinary approach. Obtaining drought-resistant plants is not easy; it entails a thorough understanding of their molecular and physiological processes, as well as the development of agronomic and crop precision techniques.
The European project TOMRES (a new and integrated approach to improve multiple and combined stress tolerance using tomato plants as a model), funded with six million Euro by the European Union through the Horizon 2020 program, seeks to improve the resistance of tomato plants to water and nutrient stress, optimising the efficiency in the use of water and nutrients in the context of climate change.
For three years, universities and research institutions across Europe*, as well as agricultural enterprises and agricultural technology services, will select varieties of drought-resistant tomatoes, study their physiological and molecular processes and develop new agronomic techniques.
The first step will be to identify the tomato varieties with the highest tolerance to water and nutrient stress, as well as the new alleles and genetic traits that give the plant greater efficiency in water and nutrient use. From a sample of more than ten thousand available copies, TOMRES will carry out a screening to select approximately two hundred that are resilient in different pedoclimatic conditions, while also maintaining the quality of the fruit and their tolerance to pests and diseases. The selection will be made taking into account the complex interactions between plants, soils and underground biodiversity. The goal is to identify between ten and twenty alleles that can be reproduced. Novel traits, in particular belowground, to be exploited in breeding, will be identified. The role of selected hormones (strigolactones and brassinosteroids) will be studied to identify further resilience traits.
TOMRES will test and optimize sustainable crop management strategies such as legume intercropping, precision fertilization and irrigation techniques, manipulation of symbiotic microorganisms, and the use of rootstocks more suited to water and nutrient uptake from the soil.
Novel genotypes X management strategies will be developed with the goal of reducing N and P application by at least 20%, water input by 40%, while granting environmental sustainability and economic viability of the solutions proposed.
Testing will be integrated with analysis of environmental (greenhouse emissions, water quality), and of socio-economic impact. Agronomical, environmental, and economical data will be processed to construction of models and of a Decision Support System.
For this experiment, the tomato plants will be divided into three plots that will be given different doses of nutrients and water, using state-of-the-art technology to carry out a detailed monitoring of their physiological and agronomic condition, including remote measurements. These data will be compared with those of another parallel experiment carried out at the German University of Bonn, but in greenhouses. The most resistant varieties will be chosen based on the results obtained.
The example of Ontario
Climate change will mean agricultural change for farmers in Windsor-Essex County. Al Douglas, director of the Ontario Centre for Climate Impacts and Adaptation Resources, says that this area can expect the average annual temperature to increase by an additional three degrees Celsius by mid-century.
“That’s pretty significant,” said Douglas. He points out that in the last 40-60 years alone, Southwestern Ontario has already seen an annual temperature rise of over one degree. “As the averages increase, so does the potential for extremes,” he said.
Environment Canada’s senior climatologist David Phillips said some crops will not survive this higher heat. “Now we have 20-24 days above 30, in 2070 we might have 50 days above 30.”
Steve Loewen, a tomato breeder from Guelph, explains that the current varieties of processing tomatoes do not fare well in temperatures above 32°C. He explained that the impact that extreme heat has on the tomatoes depends on the time of year it occurs. For example, high heat exposure early in the season when the plant is flowering may prevent it from producing fruit. But if it happens later in the season, only the colour of the tomato will be affected, he said.
The Windsor-Essex region grows large amounts of processing tomatoes, so these climate predictions are worth considering. According to Loewen, the industry will try to adapt to these changes. Growers plan to breed and select tomato plants that produce a lot of foliage. This will help protect the plant. “That way there’s less risk of them overheating,” he said.
Growing new varieties of tomatoes will allow the area to continue keeping up with demand, but climate change will take its toll in other ways.
“It will mean that our growers and our producers in Ontario won’t be able to maintain the high quality that Ontario consumers expect,” said Loewen.