To enhance the sustainability of rice production, the rice plant utilizes a tissue known as aerenchyma, which works like a chimney to allow oxygen to reach the roots and facilitate the release of methane from the soil. Methane is generated by bacteria in the soil surrounding the plant, and it is transported through the aerenchyma channel and released into the atmosphere.
To delve deeper into this relationship and determine if methane emissions can be reduced without sacrificing crop yield, a recent study published in the journal All Earth conducted research in Cali, Colombia between June and October 2019. The study focused on examining the methane emissions of four different rice cultivars, including an inbred variety, a CIAT experimental breeding line, and two hybrid varieties.
During the growing season, the experimental areas were flooded, and water was consistently applied to the regions where the different rice genotypes were cultivated. Regular collection of gas samples allowed the researchers to monitor the amount of methane emitted by each rice cultivar.
Contrary to their initial hypothesis, the study found that the hybrid rice varieties did not produce less methane per yield compared to the inbred variety. Surprisingly, the inbred variety exhibited lower methane emissions, which was attributed to its shorter roots. Certain rice cultivars allocate more photosynthetic products for root development, resulting in varying root lengths. Methanogens, which are microorganisms responsible for methane production, utilize the organic substrates provided by the roots. Consequently, the inbred variety emitted the least methane due to its shorter roots and lower aboveground biomass.
Nevertheless, the inbred variety was found to be less productive compared to the hybrid varieties. Although this drawback can be mitigated by reusing the inbred variety’s seeds without affecting yields, further research is needed to explore the potential of utilizing rice cultivars with short roots that do not compromise productivity. Such a green technology holds promise for carbon credits. However, reducing methane emissions in rice cultivation poses significant challenges, including the lack of adequate equipment to characterize aerenchyma, substantial consumables requirement, and limited human capacity. Overcoming these obstacles would require substantial financial investment.
In conclusion, this study emphasizes the significance of aboveground biomass and root size in influencing methane emissions in rice cultivars. By exploring alternative rice cultivars with shorter roots while maintaining yield, an opportunity arises to create a sustainable solution that could be rewarded with carbon credits. Additional scholarly investigations are necessary to advance our understanding of this potential green technology.
Source: Journal of Food Safety
Article: ‘Potential of rice (Oryza sativa L.) cultivars to mitigate methane emissions from irrigated systems in Latin America and the Caribbean’
Published on: 30 June 2023
DOI: https://doi.org/10.1080/27669645.2023.2207941
Authors: Abayomi Sobowale Soremia, N. Chirindaa, E. Graterolb and M. Fernanda Alvarezaa