Dry matter partitioning to leaves differentiates African and Asian rice genotypes exposed to elevated CO2

Intraspecific variation of response to elevated CO₂ (eCO₂) is a powerful option to improve crop productivity under the future climate. We evaluated genotypic variation in the biomass response to eCO₂, at 200 μmol/mol above ambient CO₂ (aCO₂) 33 to 38 days after transplanting in 7 African rice (Oryza glaberrima Steud.) genotypes and 10 Asian rice (Oryza sativa L.) genotypes during a 3‐year experiment. A comparison at vegetative growth at aCO₂, African rice genotypes showed 60% to 76% greater biomass than Asian rice genotypes. eCO₂ significantly increased biomass of both species, and the magnitude of the increase was similar between the African (by 12% to 19% of averaged over three years) and Asian accessions (7 to 24%). The genotypic variation in the biomass response to eCO₂ could be explained by the leaf area response rather than by the efficiency of biomass production per unit leaf area or leaf photosynthesis across the species. Dry matter partitioning to leaves determines biomass responsiveness to elevated atmospheric CO₂ in comparison between African and Asian rice genotypes.