Genetic selection could help farmers and breeders reduce greenhouse gases from crops, particularly rice cultivation, research by the University of Warwick and Cranfield University shows.
The intensification of farming to meet global food demand has made agriculture one of the largest contributors to greenhouse gas (GHG) emissions. While practices such as nitrogen fertiliser use are known to drive nitrous oxide (N₂O) emissions, crop varieties themselves also influence emissions. Until now, it has not been clear which varieties best balance high yields with lower GHG release.
A new study, published in Frontiers in Agronomy, has performed the first comparison of crop variety impacts on GHGs on a global scale. The analysis shows that the choice of crop variety (specifically rice) has a greater effect on methane (CH₄) emissions than fertiliser management - a critical finding given the importance of rice in global food supply.
Conor Walthall, Research Associate, University of Warwick said, "This study looked across wheat, maize, canola, soybean, and especially rice. Rice is the staple food for more than half the world's population, but rice paddies account for over 10% of global methane emissions - a greenhouse gas over 25 times more potent than CO₂. By selecting rice genotypes with lower methane emissions, without reducing yields, we can both increase food security and reduce agriculture's climate impact."
By analysing 180 crop genotypes from trials around the world, researchers discovered:
- Nitrous oxide (N₂O) emissions are closely tied to nitrogen fertiliser inputs, regardless of genetic variety.
- Methane (CH₄) emissions, by contrast, are strongly influenced by genotype, highlighting selective breeding as a key strategy for reduction.
- Yields also depend heavily on genotype, indicating opportunities to selectively breed to align productivity with sustainability.
Crop traits such as root structure, nitrogen-use efficiency, and soil interactions all influence GHG emissions and can be selectively bred. The findings suggest that while fertiliser management remains essential, breeding programmes should prioritise genetic traits that reduce methane emissions.
Senior author, Dr Alice Johnston, Lecturer in Environmental Data Science at Cranfield University, who supervised Conor as a PhD student at Cranfield, added: "Our analysis shows that genetics play a key role in methane emissions in rice, offering new opportunities to align breeding with climate goals. Breeding can help, but we also need more field trials measuring genotype impacts on GHGs in real-world farming conditions and a range of crop types to ensure gains translate to practice."
This is the first global synthesis to separate the effects of genotype and fertiliser on crop GHG emissions. The authors argue that plant genetics must be integrated into future greenhouse gas reduction strategies in agriculture.
