Elevated CO2 concentration regulate the stomatal traits of oilseed rape to alleviate the impact of water deficit on physiological properties

Abstract

There is a limited understanding of how stomatal distribution and structure affect photosynthesis under elevated CO2 concentrations (e[CO2]) and variable soil water environments. This study investigated the effects of e[CO2] on stomatal morphology and distribution, gas exchange and growth parameters of oilseed rape plants under water deficit [soil moisture decreased from 80% field capacity (FC) (W; full irrigation) to 60% FC (D1), 40% FC (D2), and < 35% FC (D3)] and re-watering conditions in growth chambers with [CO2] controlled at 400 µmol mol−1 (a[CO2]) or 800 µmol mol−1 (e[CO2]). e[CO2] had a strong CO2 fertilization effect on the net photosynthetic rate (An) and growth of plants under water deficit. Under a[CO2], stomatal density and aperture on the adaxial leaf surface increased when soil moisture decreased from W to D1, while the stomatal aperture and regularity of the spatial distribution pattern of stomata decreased with decreasing soil moisture. Stomatal conductance (gs) were 47.1% and 26.1% capacity of anatomically determined maximum anatomical conductance (gsmax) with W under a[CO2] and e[CO2], respectively. e[CO2] enhanced plant recovery after re-watering through modifying stomatal traits. This study offers insights into the trade-off between stomatal traits and gas exchange for adapting plants to future climates.