Better safe than sorry: the unexpected drought tolerance of a wetland plant (Cyperus alternifolius L.)

A common assumption of plant hydraulic physiology is that high hydraulic efficiency must come at the cost of hydraulic safety, generating a trade-off that raises doubts about the possibility of selecting both productive and drought-tolerant herbaceous crops. Wetland plants typically display high productivity, which requires high hydraulic efficiency to sustain transpiration rates coupled to CO2 uptake. Previous studies have suggested high vulnerability to xylem embolism of different wetland plants, in line with expected trade-offs. However, some hygrophytes like Cyperus alternifolius L. can also experience prolonged periods of low water levels leading to substantial drought stress. We conducted an in-depth investigation of this species' hydraulic safety and efficiency by combining gas exchange measurements, hydraulic measurements of leaf hydraulic efficiency and safety, optical measurements of xylem vulnerability to embolism, and determination of cell turgor changes under drought. Our ...