Abstract

Purpose: This study aimed to comprehensively evaluate the effects of elevated carbon dioxide (CO2) levels on wheat root biomass production, root exudates, and bacterial community structure. Methods: Wheat was evaluated in a closed system growth chamber under two CO2 conditions (CO2 550 and CO2 1000 ppm) at two growth stages (four and eight weeks). Leaf enzymatic activity (glutamate dehydrogenase and nitrate reductase), gas exchange parameters, aerial and root biomass, organic acids exuded by roots, soil microbial activity, community composition and structure, and diversity (richness and Shannon's index) were evaluated. Results: In the fourth week of growth, CO2 1000 resulted in a decrease in net photosynthesis. However, root biomass increased by 107% and malic acid by 121%, and soil bacterial activity and diversity were enhanced compared to volcanic soil from plants grown under CO2 550. In terms of richness and Shannon index, both treatments in the fourth week of growth were higher than those of CO2 1000 in the eighth week. The three predominant genera of the soil microbial community in the eighth week of growth under elevated CO2 were Stenotrophomonas, Delftia, and Chryseobacterium, which were associated with soil denitrification processes. Conclusions: These findings provide valuable insights into how the expected increase in CO2 levels may influence wheat growth, photosynthesis, nitrogen acquisition, and carbon exudation, leading to alterations in the diversity and functions of soil microorganisms. These modifications can affect the operational dynamics, ecological resilience, and sustainability of agroecosystems.