Methane Emissions among Hybrid Rice Cultivars in the MidSouthern United States

Rice (Oryza sativa L.) production systems have a greater global warming potential than upland row crops due to methane (CH4) emissions resulting from anaerobic conditions associated with flood-irrigated soils. Based on recent research indicating the potential for hybrid cultivars to mitigate CH4 emissions from rice, the objective of this study was to determine the influence of several commonly grown hybrid rice cultivars on CH4 fluxes and emissions from a silt-loam soil. Four cultivars were evaluated: the three hybrids CLXL729, CLXL745, and XL753 and the pure-line cultivar Roy J. Methane fluxes were determined by measuring changes in headspace CH4 concentrations over a period of 1 hour using 30-cm-inner-diameter polyvinyl chloride chambers. Only minor differences in CH4 fluxes occurred among the three hybrid cultivars, while the pure-line cultivar (Roy J) generally had greater (P < 0.05) fluxes. Peak CH4 fluxes occurred just after heading and were greater (P < 0.05) from Roy J (7.9 mg CH4-C m -2 h -1 ) than from the three hybrid cultivars, which did not differ and averaged 5.1 mg CH4-C m -2 h -1 . Seasonal CH4 emissions were greater (P < 0.05) from Roy J (74.8 kg CH4-C ha -1 season -1 ) than from CLXL729, XL753, and CLXL745, which did not differ, and averaged 55.3, 53.0, and 48.9 kg CH4-C ha -1 season -1 , respectively. Results of this study indicate the use of common hybrid cultivars may have potential for mitigation of CH4 emissions from rice production on silt-loam soils in the mid-southern United States.