Traditional crossbreeding reduces rice crop methane by nearly three-quarters

New Scientist unveils in its recent article that researchers have developed a new variety of rice through traditional crossbreeding techniques that could significantly reduce the crop's methane emissions. 

A new rice variety developed through basic crossbreeding techniques has the potential to cut methane emissions from rice cultivation by nearly 75 per cent. Rice farming is responsible for approximately 12 per cent of human-made methane emissions, a gas that contributes to global warming at a rate 25 times greater than carbon dioxide.

The methane emissions from rice cultivation originate from soil microbes in flooded paddy fields, where they decompose root exudates released by the rice plants. While this process provides essential nutrients for the plants, it also generates methane. 

To explore the factors influencing methane production from rice roots, Anna Schnürer and her team at the Swedish University of Agricultural Sciences grew two rice strains in a lab: Nipponbare, a Japanese variety with typical methane emissions, and SUSIBA2, a genetically modified variety known for producing less methane. SUSIBA2 emitted less fumarate, a key root exudate linked to methane production, compared to Nipponbare. However, when both strains were treated with oxantel, a chemical that prevents fumarate breakdown by bacteria, SUSIBA2 still emitted less methane. This suggested another factor was responsible for the difference between the two varieties.

Further investigation revealed that SUSIBA2 was secreting high levels of ethanol, which appeared to suppress methane emissions. To capitalize on this, the team used traditional breeding methods to create a new rice strain by crossing a high-yield variety with the Heijing cultivar, known for producing low fumarate and high ethanol. After two years of field trials in China, the new strain yielded over 8 tonnes per hectare, significantly higher than the global average of 4 tonnes, and emitted 70 per cent less methane than its parent variety.

Johannes le Coutre from the University of New South Wales in Sydney, Australia, views the study as an excellent example of thorough research into the causes of greenhouse gas emissions from rice crops. 

“The core point of the study is they don’t use hard-core gene engineering or editing technologies or transgenic approaches,” says le Coutre. “They use traditional crossbreeding in order to create new rice lines which lower the synthesis of methane.”

By Naila Huseynova