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Fast yielding rice varieties could help reduce greenhouse gas emissions

In a recent study conducted by the researchers from ICAR-National Rice Research Institute, Cuttack and their collaborators, researchers have studied the mechanism of methane gas emission by seven varieties of rice grown in  Eastern India. The study was published in the journal Science of The Total Environment.

Greenhouse gases, like methane, trap heat in the atmosphere and contribute to global warming. Methane is considered as the second greatest contributor to human-mediated climate change. Rice, a sustainable food crop, is one of the major culprits releasing methane to the atmosphere. Flooded rice fields are fertile grounds for bacteria that produce methane by degrading organic matter in the soil. The litters of the rice plants and the organic compounds (exudates) released by the roots serve as a major substrate for the production of methane. Besides, the rice plants also transfer methane from the soil to the atmosphere through the capillary pores present in the plant.

The researchers of the current study selected seven rice varieties based on the duration of their life cycle and analysed their methane emission. They measured the rate of methane emission, root exudates released by the plants and the pore spaces in the shoot aerenchyma- the spongy tissue which helps in exchange of gases.

“The rate of methane emission was controlled by the orientation of aerenchyma, root exudation, and biomass production rate which are the key specific traits of a cultivar”, comment the researchers on their main findings.

The researchers infer that these traits are associated with the duration of these cultivars and their adaptability. “The methane emission rates were lowest in the short duration cultivars followed by medium and long duration ones. The average methane emission rate per unit grain yield was also relatively less in short and medium duration cultivars” say the authors.

Significant variations in the methane emission rate among the cultivars proved that suitable selection of varieties might help to address the problem of methane emission.

“There is a possibility to breed rice cultivars depending on ecology, duration and having less methane emission potential, which could be effectively used in greenhouse gas mitigation strategies”, conclude the researchers.