Drought priming enhances photosynthesis and growth of the ephemeral plant Erodium oxyrhinchum

Abstract

The increasing frequency and intensity of drought events due to climate change pose significant challenges to plant growth. However, it remains unclear whether drought priming during early growth stages can enhance plant resilience and mitigate the adverse effects of severe drought stress. To address this, we conducted an experiment on the desert ephemeral plant Erodium oxyrhinchum to examine its photosynthesis and growth responses to drought priming in the Gurbantunggut Desert, China. The field experiment included two treatments: (1) drought priming applied twice at the seedling stage followed by severe drought stress at the reproductive stage, and (2) adequate irrigation at the seedling stage followed by severe drought stress at the reproductive stage. Our results showed that drought priming significantly reduced stomatal conductance during the full leaf expansion stage, but enhanced net photosynthesis at the initial flowering stage. Compared to the control, drought-primed plants exhibited lower intercellular CO₂ concentrations at both the full leaf expansion and initial flowering stages, along with increased stomatal limitation and intrinsic water use efficiency. Additionally, drought priming significantly elevated superoxide dismutase activity and soluble sugar accumulation at the initial flowering stage. Throughout the plant’s life cycle, free proline and soluble sugar concentration initially increased and then declined, with both superoxide dismutase activity and soluble sugar concentration remaining significantly higher at the initial flowering stage under drought priming. These findings indicate that drought priming enhances stress tolerance by activating protective metabolic mechanisms, reducing transpiration, and improving both water use and photosynthetic efficiency. Finally, drought-primed plants not only exhibited greater resilience to severe drought stress but also demonstrated compensatory growth, leading to increased individual total biomass and reproductive output. Therefore, drought priming may serve as a promising strategy for sustaining plant growth under extreme drought conditions and offers valuable insights for vegetation restoration in arid and semi-arid ecosystems.