Changes in nutrient uptake and utilization by rice under simulated climate change conditions: A 2-year experiment in a paddy field

Global climate change with elevated atmospheric CO2 concentration and temperature has been known impacting plant photosynthesis and grain yield in agroecosystems. However, how nutrient uptake and utilization by rice change under climate change stresses has been poorly addressed. An open-air field experiment was conducted to investigate the impacts of factorial combinations of CO2 enrichment (up to 500 ppm) and canopy warming (+2 °C) on nutrient concentration (PNC), accumulation (PNA) and utilization efficiency (NUE) for two cropping years in a paddy from southeast China. Plant samples of aboveground biomass were collected across the growing stages and grain yield measured at harvest. Compared to ambient condition, CO2 enrichment more or less decreased PNC of N, P and K, but unchanged PNA of N and P while increased aboveground biomass. In contrast, warming increased PNC of N, P and K respectively by 7.4%, 11.0% and 13.4% at the ripening stage, but decreased PNA of N, P and K respectively by 18.6%, 22.6% and 10.8% in 2013. Whereas, concurrent CO2 enrichment and warming unchanged PNC but slightly decreased PNA of N and K in both years. In addition, CO2 enrichment unchanged the apparent NUE, but increased NUE of N and K under concurrent warming in both years. Therefore, canopy warming may have impacted the rice response in NUE to CO2 enrichment as the change in PNA with concurrent CO2 enrichment and warming was in a similar trend to that with warming alone. Our findings suggest that nutrient uptake and utilization by rice are more impacted by warming compared with CO2 enrichment under the simulated climate change conditions. Therefore, simulated climate change experiments should be conducted regarding how simultaneous atmospheric CO2 enrichment and warming influences plant traits and functions in rice paddy, to provide a better understanding of agricultural production changes and sustainable nutrient management under future climate change.