Carbon dioxide responsiveness mitigates rice yield loss under high night temperature

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] (e[CO₂]) 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 e[CO₂] using a free-air [CO₂] enrichment facility in 2017. The most promising genotypes and positive and negative controls were tested under HNT and e[CO₂] + 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 e[CO₂]. 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.