Abstract: The effects of reduced solar irradiance on soil microbial diversity in winter wheat (Triticum aestivum) rhizosphere were investigated in a two-year experiment using a shading method. Solar irradiance was reduced by 20%, 40%, and 60%, respectively, with unshading as controls. The catabolic ability of single carbon source was measured by BIOLOG ECO MicroPlate. Average well-color development (AWCD), soil microbial diversity index and principal component analysis (PCA) were calculated. The results showed that, under the reduced solar irradiance, the catabolic ability of single carbon source was decreased, with a slower decomposition rate of total carbon sources. However, we found no obvious influence of reduced solar irradiance on dominant soil microbial populations, community richness, and the number of individuals in the community. The microorganisms weakened their ability to metabolize majority of carbon sources under the reduced solar irradiance. The metabolism of saccharides was most affected, with a greater variation compared to other carbon sources. The results indicate that microbial carbon metabolism in the wheat rhizosphere soil was affected by the reduced solar irradiance. This study provided a reference for understanding the impact of atmospheric environmental change on soil microecology.

Key words: cucumber, drought, adventitious root, calcium ion, nitric oxide, antioxidant enzymes