Identifying rice varieties for mitigating methane and nitrous oxide emissions under intermittent irrigation

Area of Science:

• Agricultural Science
• Environmental Science
• Climate Change Research

Background:

• Continuous flooding in rice cultivation research for greenhouse gas (GHG) mitigation is common, but intermittent irrigation is increasing globally due to water scarcity.
• Intermittent irrigation practices can alter methane (CH₄) and nitrous oxide (N₂O) emissions, impacting overall global warming potential (GWP).
• Identifying rice varieties that reduce both CH₄ and N₂O emissions while maintaining yield under intermittent irrigation is critical for climate-smart rice production.

Purpose of the Study:

• To assess CH₄ and N₂O emissions, grain yield, and GWP of four rice varieties under intermittent irrigation in Colombia.
• To identify rice varieties suitable for climate-smart agriculture and water-scarce conditions.

Main Methods:

• Evaluation of four commercial rice varieties over two seasons (wet and dry) in 2020 and 2021.
• Field experiments conducted in two Colombian regions: Tolima and Casanare.
• Measurement of CH₄ and N₂O emissions, grain yield, and calculation of GWP.

Main Results:

• Crop productivity varied between seasons and locations; some varieties showed reduced yield during the dry season due to water stress.
• Methane (CH₄) emissions and GWP were generally low due to frequent drainage, but nitrous oxide (N₂O) emissions contributed significantly (73%) to GWP.
• Specific varieties (F67 in Tolima, F-Itagua in Casanare) reduced GWP by 32-61% by decreasing N₂O emissions, not CH₄.

Conclusions:

• Rice varietal selection can effectively mitigate GWP under intermittent irrigation with minimal impact on grain yield.
• Reducing N₂O emissions through strategic variety selection is key for lowering GWP in rice systems adapting to water scarcity and climate change.