Rice Growth, Yield Formation, and Methane Intensity Responses to GroMore® Programs and Nitrogen Rate in a Korean Paddy Field

Rice production in flooded paddy systems must increasingly balance grain productivity with greenhouse gas (GHG) efficiency. This study evaluated two GroMore® crop-protection program variants under two nitrogen input levels in a temperate Korean paddy field to determine whether these treatments could improve yield-scaled climate performance without compromising grain yield. Heading date was identical across all treatments, indicating that treatment effects were not attributable to phenological shifts. Grain yield ranged from 6.87 Mg ha−1 in the conventional treatment to 9.88 Mg ha−1 in GroMore-Duo N90. GroMore-Star N90 maintained high yield (9.05 Mg ha−1) with the lowest greenhouse gas intensity (GHGI; 0.69 kg CO2-eq kg−1 grain) and reduced cumulative methane emission by 10.6% relative to the conventional treatment. Logistic analysis showed that the GroMore treatments reached the methane-accumulation inflection point earlier than the control and conventional treatments. GroMore-Duo N90 and GroMore-Star N90 reached this point at approximately 69 days after transplanting, whereas the control and conventional treatments reached it at 86 and 89 DAT, respectively. Overall, the GroMore programs were associated with differences in yield components and yield-scaled climate performance under flooded paddy conditions without changing crop phenology.