Hyperspectral pressure-volume curves to estimate leaf turgor loss

Turgor Loss Point (TLP) is an important proxy for plant drought tolerance, species habitat suitability, and drought-induced plant mortality risk. Thus, TLP serves as a critical tool for evaluating climate change impacts on plants, making it imperative to develop high-throughput and in-situ methods to measure TLP. We developed hyperspectral pressure-volume curves to estimate TLP using leaf spectral reflectance. First, we developed PLSR models to estimate leaf water potential (WP or psi) and relative water content (RWC) using spectral reflectance (400-2400 nm). We used estimated values to construct hyperspectral PV-curves and compared the accuracy of estimating TLP from reflectance to empirical PV-curves using the Pressure-Volume Analysis Spreadsheet tool (PVAST, the most widely used analytical method; Sack et al., 2010). Additionally, we compared TLPs extracted from PVAST to TLPs automatically extracted by segmented regression, a tool commonly used to automatically parameterize physiological.