Are leaf chlorophyll fluorescence and Dark Green stressor-specific fingerprints in grapevine under drought or salt stress? A reanalysis study

Early and accurate recognition of abiotic stress types is essential for accelerating the selection of stress-tolerant varieties and implementing effective management strategies. This study is motivated by the socio-economic relevance of vineyard and by the increasing need for stressor-specific fingerprint(s) to support the reliable identification of stress type (e.g., drought or salinity) within a high-throughput plant phenotyping domain. This paper presents a reanalysis of physiological and phenotyping data from drought and salt stress experiments in Vitis vinifera focussing the maximum photosynthetic efficiency (Fv/Fm) and leaf Dark Green color. The reanalysis suggests that salt-stressed vines might suffer additional (non-stomatal) limitations curbing net photosynthetic rate (Pn) severely as drought stress does at equivalent stomatal conductance (gs) levels. Through a Principal Component (PC) Analysis, physiological and colorimetric response variables were decomposed revealing that Fv/Fm and Dark Green dominates the non-stomatal PC (∼80 %) clustering data between salt and drought experiments. Confusion matrices reveal that model based on Fv/Fm and Dark Green performed better (accuracy = 1, precision =1) than that based on Pn, gs, transpiration, and stem water potential. This study supports the potential use of Fv/Fm and Dark Green for early and non-destructive stress type identification.