A new protocol for psychrometric pressure–volume curves of fern gametophytes

PREMISE: Pressure–volume curves are a widely used analytical framework to derive several key physiological traits related to plant–water relations, including a species’ turgor loss point, osmotic potential at full turgor, and the elasticity of cell walls. We developed a novel protocol, including the preparation and treatment of fern gametophytes, to generate data for pressure–volume curve analyses using thermocouple psychrometry. METHODS AND RESULTS: Gametophytes of the fern species Polystichum lemmonii were grown from spore, harvested, and subjected to a series of drying intervals. We constructed pressure–volume curves using thermocouple psychrometers to calculate gametophyte water potential and a balance to measure relative water loss. CONCLUSIONS: We present the first protocol for fern gametophyte pressure–volume curves that can accurately determine key physiological traits in fern gametophytes such as the turgor loss point and osmotic potential at full turgor.