[Response of Yield, CH, and NO Emissions from Paddy Fields to Long-term Elevated CO Concentrations].

Elevated atmospheric CO concentrations([CO]) are the main driving force of global climate change, which directly and indirectly affect carbon and nitrogen cycling in the paddy ecosystems. Therefore, understanding the response of rice yield and greenhouse gas emissions to long-term(more than 10 years)[CO] from paddy fields is of great significance for food security and future climate change assessment. In this study, strongly and weakly responsive cultivars were used as the experimental materials. Based on a free-air CO enrichment(FACE) platform continuously run for 14 years, two treatments of different[CO] were set:a control(i.e., normal[CO] and[CO]) and a 200 μmol·mol higher than[CO] condition, ([CO]). CH and NO emissions from the rice paddy fields were monitored in situ by static transparent chamber-gas chromatography, and grain yields were also obtained. The results showed that compared with the[CO] treatment, long-term[CO] increased grain yields of the strongly and weakly responsive cultivars by 29%-31%(<0.05) and 12%-14%(>0.05), and CH emissions of the strongly and weakly responsive cultivars were reduced by 21%-59% and 11%-54%, respectively. Furthermore, NO emissions from the strongly and weakly responsive cultivars were significantly reduced by 70%(<0.05) and 40%(<0.05), respectively. The short- and long-term responses of grain yields and CH emissions from rice paddy fields to[CO] were significantly different. Specifically, with the increase in the duration of[CO], the increases in rice yields and CH emissions significantly decreased, while the NO emissions showed no significant changes. Therefore, under long-term[CO] conditions, the strongly responsive cultivar has a high potential to reduce greenhouse gas emission and increase grain yields.