Transgenerational effects of elevated CO2 on rice photosynthesis and grain yield

Key message The maternal carbon dioxide environment affected the responses of offspring to elevated carbon dioxide with regard to stomatal density, photosynthesis and yield. The responses of crops to rising carbon dioxide concentration ([CO2]) are often validated using single-generation short-term experiments. However, the transgenerational effects of elevated [CO2] on rice growth have received little attention. Here, we set up ambient [CO2] (a[CO2]) and elevated [CO2] (e[CO2], a[CO2] + 200 mu mol mol(-1)) treatments using open-top chamber (OTC). Rice was cultivated in different [CO2] treatments over five growing seasons in 2016-2020. Beginning in 2017, rice seeds harvested in the previous year under a[CO2] and e[CO2] conditions were planted in their respective growing environments. In 2021, seedlings derived from a[CO2] maternal treatment (a[CO2](m)) and e[CO2] maternal treatment (e[CO2](m)) were planted with both a[CO2] offspring (a[CO2](o)) and e[CO2] offspring (e[CO2](o)) conditions to investigate the transgenerational effects of e[CO2]. Leaf gas exchange and grain yield under different conditions were determined in 2021. The results showed that light-saturated net photosynthesis (A(sat)) and stomatal conductance of offspring from e[CO2](m) were significantly lower at the heading and grain-filling stages under e[CO2](o) compared with a[CO2](m), and the corresponding stomatal density was also significantly lower. Moreover, A(sat) was positively correlated with stomatal density. These results suggest that transgenerational effects induce a decrease in stomatal density and thus cause a lower benefit of A(sat) from e[CO2](o). These findings contribute new insights into predicting crop growth and yield in the future.

Automated summary

The maternal carbon dioxide environment affects the response of rice offspring to elevated carbon dioxide, resulting in decreased stomatal density and photosynthetic benefits. These findings contribute new insights into predicting future crop growth and yield.