Differential crop yield responses to elevated CO₂ attributed to varying biomass part stimulations: a meta-analysis

Elevated carbon dioxide (eCO₂) is known to enhance biomass accumulation and plant growth by improving photosynthesis and promoting stomatal closure. However, the effects of CO₂ fertilization on aboveground and belowground biomass differ significantly among crops, which may influence agricultural productivity and carbon storage in plants and soils. This study aims to quantify impacts of eCO₂ on crop yield and biomass and to identify the key factors influencing crop yield responses.

This study analyzed the biomass changes in response to eCO₂ and its impacts on agricultural yields dedicated to major crops, i.e., maize, rice, and wheat, using a meta-analysis method based on 757 pairs of global observations from 178 peer-reviewed articles.

The results indicated that eCO₂ increased the yields of maize, rice, and wheat by approximately 12%, 17% and 22%, respectively. Variation in biomass accounted for 39%, 28% and 43% of the yield response in these three crops, respectively. In maize and rice, the non-yield components of the aboveground biomass posed direct effects and acted as mediating variables, whereas in rice, the belowground biomass was more influential.

The present findings revealed the dominant role of various biomass components in determining the impact of eCO₂ on agricultural productivity. In rice, belowground biomass was identified as the most significant factor affecting the yield response to CO₂ fertilization. For maize and wheat, the non-yielding fraction of the aboveground biomass was the most important factor.