Cultivar-specific methane emissions and yield-scaled greenhouse gas intensity responses to transplanting date: a case study in South Korea

In a South Korean field study, researchers examined the impact of varying rice transplanting dates on methane (CH4) emissions and yield-scaled greenhouse gas intensity (GHGI_CH4). Using two rice cultivars - Koshihikari and Chamdream - transplanted between May 10 and June 25 under constant flooding, the study aimed to find a transplanting schedule that minimizes CH4 emissions without reducing grain yield.

Both cultivars did not exhibit significant differences in grain yield across transplanting dates within each cultivar-year pair, except for Chamdream in 2023, which showed a lower yield with the May 10 treatment compared to later dates. Seasonal CH4 emissions increased from 2023 to 2024, with treatment-specific increases from 1.3- to 2.5-fold.

The lowest GWP_CH4 and GHGI_CH4 values were recorded during mid-to-late June dates. For Koshihikari, the optimal date was 25 June in both years, while for Chamdream, the best date shifted from 10 June (2023) to 25 June (2024). The study concludes that a cultivar-specific mid-to-late June window is more effective than a universal optimum for reducing CH4 emissions without sacrificing yield.

This research was funded by the Rural Development Administration of Korea and published under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.