Carbon dioxide fertilization effect on rice yield is not sustained over multiple generations

<h2>Summary</h2> Global crop production needs to increase to meet the growing demand for food. Rising atmospheric CO₂ concentration offers opportunities to increase global productivity via the CO₂ fertilization effect on C₃ crops (including rice, <i>Oryza sativa</i> L.). However, whether the CO₂ fertilization effect can be sustained over generations remains unclear. Here, we show that the CO₂ fertilization effects on aboveground biomass, aboveground nitrogen uptake, and yield strongly depends on the number of generations in maternal elevated CO₂ (eCO₂) for rice cultivars Yangdao 6 (Y6; indica subspecies) and Wuyungeng 23 (W23; japonica subspecies) in free-air CO₂ enrichment (FACE) experiments. DNA methylation and transcriptome changes provided epigenetic evidence on the multigenerational effects of maternal eCO₂ on aboveground biomass, aboveground nitrogen uptake, and yield in both cultivars/subspecies. Our results highlight that data from multigenerational exposure to FACE experiments are needed to accurately predict crop production and food security in a future high-CO₂ world.