Abstract: | Increasing night-time temperatures are a major threat to sustaining global rice (Oryza sativa L.) production. A simultaneous increase in CO2] will lead to an inevitable interaction between elevated CO2] (eCO2]) and high night temperature (HNT) under current and future climates. Here, we conducted field experiments to identify CO2] responsiveness from a diverse indica panel comprising 194 genotypes under different planting geometries in 2016. Twenty-three different genotypes were tested under different planting geometries and eCO2] using a free-air CO2] enrichment facility in 2017. The most promising genotypes and positive and negative controls were tested under HNT and eCO2] + HNT in 2018. CO2] responsiveness, measured as a composite response index on different yield components, grain yield, and photosynthesis, revealed a strong relationship (R2 = 0.71) between low planting density and eCO2]. The most promising genotypes revealed significantly lower (P < 0.001) impact of HNT in high CO2] responsive (HCR) genotypes compared to the least CO2] responsive genotype. CO2] responsiveness was the major driver determining grain yield and related components in HCR genotypes with a negligible yield loss under HNT. A systematic investigation highlighted that active selection and breeding for CO2] responsiveness can lead to maintained carbon balance and compensate for HNT-induced yield losses in rice and potentially other C3 crops under current and future warmer climates. Active selection for carbon dioxide responsiveness in rice and other C3 crops can mitigate yield loss induced by high night temperature. |