Melatonin regulates material transport to reduce carbon emissions and increase yield under different nitrogen in rice

Carbon and nitrogen metabolism regulates yield formation and greenhouse gas emissions in rice. Melatonin can promote stress resistance under abiotic stress, but its ability to regulate carbon and nitrogen transport remains unclear. Therefore, this study explored the response mechanism of melatonin in rice under reduced nitrogen application. To further understand whether melatonin regulates carbon and nitrogen transport to increase production and reduce greenhouse gas (GHG) emissions. At the heading stage, 100 mu mol L-1 melatonin was sprayed under normal fertilization, 85% nitrogen, 50% nitrogen, and 0% nitrogen treatments. Physiological detection, metabolomics analysis, and gas chromatography were used to study the response mechanism of melatonin to carbon and nitrogen metabolism accumulation and transport, and its effect on greenhouse gas emissions under different nitrogen fertilizer conditions was studied. The results revealed that melatonin could improve the genes related to sucrose transporter and nitrogen uptake under the condition of a 15% reduction of normal nitrogen application, thereby increasing the content of non-structural carbohydrates and nitrogen, promoting their transport to grains, and reducing rhizosphere transport to reduce greenhouse gas emissions. There was no significant difference in yield between the melatonin treatment and normal fertilization under 15% nitrogen fertilizer reduction, but methane and nitrous oxide emissions were significantly reduced. The results of this study provide preliminary evidence for the response mechanism of exogenous melatonin to carbon and nitrogen metabolism in rice under different nitrogen treatments.