The rice plants don't absorb or release methane, the breakdown of organic matter in the flooded ricefields causes the release of methane. In dry/unflooded field

The rice plants don't absorb or release methane, the breakdown of organic matter in the flooded ricefields causes the release of methane. In dry/unflooded fields, the decay would be much slower. The flooded fields possibly emit more methane and less CO2 than unflooded due to anaerobic conditions, but I'm just guessing.