Methane and nitrous oxide emission characteristics of high-yielding rice field

As representative varieties of the four phases of the super rice breeding project in China, Lianyoupei 9 (LYP9), Y Liangyou 1 (YLY1), Y Liangyou 2 (YLY2), and Y Liangyou 900 (YLY900) achieved higher yield under optimal cultivation techniques. However, the impact of these high-yield rice varieties on greenhouse gas (GHG) emissions under high-yield cultivation management practices remains poorly understood. In this study, we conducted field experiments to investigate CH₄ and N₂O emissions from paddies containing four elite rice varieties, managed with field drying at the ineffective tillering stage and alternate wet/dry irrigation at the grain-filling stage. The plants were fertilised with nitrogen (N) at three different rates. The results showed that CH₄ emission was highest at the tillering stage. N₂O emission flux was dramatically increased by field drying at the ineffective tillering stage, and with the rate of N application. Rice variety was among the most important factors affecting CH₄ emission and global warming potential (GWP). N₂O emission was mainly related to N application rate rather than rice variety. YLY2 achieved higher yield than LYP9, YLY1, and YLY900, and lower GHG emission than YLY900. Our results indicate that rice variety should be considered as a key factor to reduce GHG emissions from rice paddies under high-yield cultivation practices. Based on its high yield and low GHG emission at the study site, YLY2 may be an optimal rice variety.