Rapid Determination of Bud and Leaf Water Content Using Hyperspectral Sensors to Monitor Cold Hardiness in Grapevine

Supplemental Table 1  Data distribution statistics of leaf physiological traits and canopy multispectral indices measured in summer 2024. SD, standard deviation.

Supplemental Figure 1  Monthly averages of solar radiation and soil tension (A); total precipitation (B); and average, maximum, and minimum air temperatures and soil temperature (C) at the field site in winter and spring 2023 to 2024; and summer, fall, and winter 2024 to 2025. Red arrows indicate the respective temperature drop during the sample collection in mid-winter of both year ranges; yellow arrows designate the leaf physiology measurement time windows at preveraison (PV; early June) and veraison (V; between July and August), allowing to quantify the possible carryover effects of winter 2023 to 2024 on the subsequent season’s growth and yield. Different background colors demarcate different seasons in each year on the graphs.

Supplemental Figure 2  Correlation matrix showing the significance (based on p value) of relationships among leaf physiological traits measured pre- and postveraison, canopy spectral indices (structure independent pigment index [SIPI], carotenoid reflectance index [CRI], anthocyanin reflectance index [ARI], and normalized difference vegetation index [NDVI]), and cluster and berry size measured during summer 2024 and average low-temperature exothermic data (BudLTE) measured (based on differential thermal analysis) in winters 2023 to 2024 (2023_24) and 2024 to 2025 (2024_25). Ver, physiological measures observed at veraison; Pre, physiological measures observed at preveraison; g_s, stomatal conductance (mol H₂O/m²/sec); ET, evapotranspiration (mmol H₂O/m²/sec); VPD, leaf-to-air vapor pressure deficit (kPa); LW, leaf water (%); LH, leaf humidity (%); LT, leaf temperature (°C); ETR, electron transport rate (μ mol/electrons m²/sec); Ltdiff, leaf temperature differential; Fm, maximum fluorescence, Fo, minimum fluorescence; Fs, steady state fluorescence; Fv/Fm, photochemical maximum quantum efficiency; Phi2, photosystem II quantum yield.

• 25-019_SupplementalData.pdf