Abstract

Field experiments were conducted during the 2007 to 2008 winter wheat-growing season to investigate the influence of enhanced UV-B radiation on diurnal variations in soil CO₂ fluxes and nitrous oxide (N₂O) emissions from a winter wheat ecosystem. CO₂ and N₂O fluxes were measured by static opaque chamber-gas chromatograph technique. Results showed that on sunny days, soil CO₂ fluxes and N₂O emissions from the soil-wheat system exhibited obvious diurnal variation patterns, which enhanced UV-B radiation. During the jointing, booting, and heading stages, enhanced UV-B radiation significantly decreased the mean diurnal CO₂ fluxes of the soil by 49.62% (p = 0.000), 50.39% (p = 0.004) and 51.44% (p = 0.022), respectively. Enhanced UV-B radiation also reduced the mean diurnal N₂O fluxes (MNF) of the soil-wheat system by 48.35% (p = 0.017) and soil MNF by 36.87% (p = 0.027) during the grain-filling stage. Our findings suggested that enhanced UV-B radiation did not change the diurnal variation patterns of soil CO₂ fluxes and N₂O emissions from the soil-wheat system, but influenced mean diurnal CO₂ and N₂O fluxes.

Key words: Enhanced UV-B radiation, winter wheat, soil, CO₂, nitrous oxide.