Hyperspectral signals in the soil: Plant–soil hydraulic connection and disequilibrium as mechanisms of drought tolerance and rapid recovery

Abstract

Abstract Predicting soil water status remotely is appealing due to its low cost and large‐scale application. During drought, plants can disconnect from the soil, causing disequilibrium between soil and plant water potentials at pre‐dawn. The impact of this disequilibrium on plant drought response and recovery is not well understood, potentially complicating soil water status predictions from plant spectral reflectance. This study aimed to quantify drought‐induced disequilibrium, evaluate plant responses and recovery, and determine the potential for predicting soil water status from plant spectral reflectance. Two species were tested: sweet corn ( Zea mays ), which disconnected from the soil during intense drought, and peanut ( Arachis hypogaea ), which did not. Sweet corn's hydraulic disconnection led to an extended ‘hydrated’ phase, but its recovery was slower than peanut's, which remained connected to the soil even at lower water potentials (−5 MPa). Leaf hyperspectral reflectance successfully predicted the soil water status of peanut consistently, but only until disequilibrium occurred in sweet corn. Our results reveal different hydraulic strategies for plants coping with extreme drought and provide the first example of using spectral reflectance to quantify rhizosphere water status, emphasizing the need for species‐specific considerations in soil water status predictions from canopy reflectance.

Plant phenotyping relevance

植物の葉のハイパースペクトル反射から土壌・根圏の水分状態を推定する手法を明示的に評価し、種間で予測性能を検証しているため、手法応用・検証として中心的です。

Code and data availability

The paper's phenotype data (spectral reflectance, water potentials, RWC/EWT) and PLSR analysis are not publicly deposited; the data availability statement requires contacting the corresponding author. The HyperPRI dataset and CubeNET model are cited prior work, not this paper's own assets.

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