| Climate warming presents significantly asymmetric trends with greatly seasonal and diurnal differences, greater temperature elevations existing in the winter-spring season than in the summer-autumn season and at the nighttime than at the daytime. We performed field warming experiment under the technique of passive nighttime warming to investigate the impacts of night warming on rhizospheric respiration and soil basal respiration during winter wheat growing stages. A LI-8100 carbon flux system was used to measure seasonal variation in soil respiration components during key growing stages. The results showed that seasonal averaged values of total soil respiration and rhizospheric respiration under nighttime warming condition were 4.32 μmol·m-2·s-1 and 3.29 μmol·m-2·s-1, and were 10.0% and 15.4% higher than the control treatments, respectively. This indicated that nighttime warming significantly increased total soil respiration and rhizospheric respiration in winter wheat soil. When taking the different growing stages into account, warming increased rhizospheric respiration during booting stages by 34.6%~44.2%, whereas decreased it during late growing stage by 31.4%~40.4%。In contrast, nighttime warming decreased soil basal respiration during booting stages and to some extent promoted it during late growing stages. It could be concluded that nighttime warming stimulated rhizospheric respiration and to some extent inhibited soil basal respiration, which resulted from nutrient competition between crop roots and soil microorganism as a result of the increase of plant biomass and nutrient uptake of wheat under warming. |
