Pressure‐volume relationships in non‐rehydrated tissue at various water deficits

Abstract. The purpose of this paper is to examine a technique for estimating the weight at full saturation (W_s) from pressure‐volume (P‐V) analysis of non‐rehydrated plant tissue at various water deficits. Tissue samples are typically rehydrated prior to P‐V analysis to determine W_s, necessary to calculate many tissue water parameters. However, several studies have indicated that artificial rehydration may significantly alter P‐V relationships, such as the plateau effect, resulting in erroneous measurements of tissue elasticity and osmotic potentials. The results of this study suggest that linear regression of P‐V data at and above the turgor loss point may be used to extrapolate W_s from non‐rehydrated samples at various moisture deficits, thus eliminating the plateau effect and other potential rehydration problems. Determination coefficients and standard errors of the Y‐intercept indicated a strong linear relationship between tissue fresh weight and water potential (Ψ), and a high degree of predictability of W_s in all but one of the species‐treatment combinations evaluated in this study, despite predawn Ψ as low as ‐ 1.0 MPa.