The diversity and capacity of maize to adapt to a changing climate rests in the hands of farmers

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Having a variety of seeds from local maize landraces allows farmers to select those that might be better adapted to disadvantageous climatic conditions. In a town of the state of Yucatán in southeastern Mexico, safeguarding this diversity has been the result of local farmers exchanging their seeds.

This was the main finding of a recently published article in the journal Agriculture and Human Values. The team of researchers showed that protecting the diversity of the most consumed grain in Mexico rests on the community. 

“It’s not only important to make a list of the diversity of seeds, but to know how this diversity moves and lives in the hands of farmers,” says Marianna Fenzi, science historian who studies agriculture and ethnoecology at the Swiss Federal Institute of Technology Lausanne (EPFL) and first author of the study in an interview for Botany One.

Growing maize under challenging climatic conditions

Farmers are now facing more extreme conditions for growing crops because of climate change. In the southern United States, for example, it is expected that the timing of the rainy season and the intensity of precipitation will continue to increase during this century. 

In tropical and subtropical regions, including Mexico, projections show there will be a decrease in maize yield in areas relying on rainfall, according to research published in 2014 in Proceedings of the National Academy of Science.

Farmers in Yucatán are aware of the changes in local climate 

The team of scientists Fenzi led examined the events of 2012 in the municipality of Yaxcabá in Yucatán. That year the area received an unusual amount of rainfall which affected the slash-and burn process (roza, tumba y quema) that farmers use to clean the planting surface and enrich the soil with nutrients. This forced farmers to reduce the surface destined for maize and, in some cases, even plant earlier. 

“They say times are changing,” explains Ángel Cruz-Estrada, coauthor of the publication at the Innovation Centre for the Development of Sustainable Apiculture of Quintana Roo. The agricultural engineer explains that farmers use environmental cues, like those they see in the sky or in the behaviour of certain animals like squirrels, to know when to expect intense rain or drought, but “all of a sudden there was heavier rainfall that they couldn’t explain; it’s not like before where they could predict when was the best time to plant corn,” he says. 

The flow of maize diversity 

Mexico is the birthplace of maize holding the largest genetic diversity with 59 landraces and thousands of different varieties. This is the result of local community practices who save seeds of local landraces that may be more resilient to challenging weather conditions. 

“The diversity of maize is important because by having a variety of seeds farmers can select those that better cover their needs and that adapt better to different agroclimates, not only in Mexico, but around the world,” Fenzi explains. 

The team found that to cope with the unusually heavy rain of 2012 farmers planted the most reliable of their local landraces, like the traditional X-nuuk nal, which they recovered after harvest. 

The researcher explained that creolized maize landraces are genetically diverse, making them adaptable to different agricultural systems, climates and temperatures; they are highly plastic. These landraces also have abundant and thick leaves which shield corncobs from insects. These traits are different from the more commercial hybrid corn that depends on industrial watering systems. 

Another reason why farmers plant local landraces also has to do with cuisine.  “Farmers keep their local seeds (also known as creolized or criollas) because they like to eat different types of food; for example, they might prefer a blue or pink tortilla because they consider them to have better flavour, or they choose corn that is good for preparing atol, pozol or tamal,” Cruz-Estrada comments.

The research team wondered how farmers keep maize diversity. They asked questions during 3 years (from 2011 to 2013) to find out the type of plants farmers grew and the characteristics of their milpa, a plot where maize, squash and beans are grown. To understand the specific practices around maize, researchers asked detailed questions about seed transactions among farmers. During this time they also took special notice of the milpa cycle. Then, using precipitation data collected from 1960 until 2013, they analysed the cultivation strategies farmers used. 

“Farmers cannot be resilient by themselves; they need their community, the social system built around their family. With our work we show that protecting biodiversity is done at the community level, building upon the relationships among people,” Fenzi highlights. 

“Seeds are always exchanged among farmers. If one of them loses his seeds after a bad harvest, another farmer, who may have also planted the same landrace and obtained better yield, might exchange or sell his seeds. This guarantees the system will be restored because next year this farmer will be able to plant seeds that he got from someone else,” Cruz-Estrada, adds. 

The researchers agree that to achieve a more sustainable type of agriculture, where less water and fertilisers are needed, it is crucial to safeguard the diversity of seeds so that climate change adaptation can happen faster. 

“Changes have to take place at different levels [political, technological and social] and above all we need to attend to the needs of farmers,” Fenzi concludes. 

RESEARCH ARTICLE

Fenzi, M., Rogé, P., Cruz-Estrada, A. et al. Community seed network in an era of climate change: dynamics of maize diversity in Yucatán, Mexico. Agric Hum Values (2021). https://doi.org/10.1007/s10460-021-10249-3

Yanine Quiroz is a reporter who writes environmental stories. She reports on climate change and other environmental issues for outlets such as Botany One, Animal Político, Animal Mx and Este País magazine. She informs about climate for society as a whole and is member of the Mexican Network of Science Journalists. She has also worked in the academic analysis of climate reporting. Follow her on Twitter @YanineQuiroz. 

English translation by Lorena Villanueva Almanza