Detection of the metabolic response to drought stress using hyperspectral reflectance.

Abstract

Drought is the most important limitation on crop yield. Understanding and detecting drought stress in crops is vital for improving water use efficiency through effective breeding and management. Leaf reflectance spectroscopy offers a rapid, non-destructive alternative to traditional techniques for measuring plant traits involved in a drought response. We measured drought stress in six glasshouse-grown agronomic species using physiological, biochemical, and spectral data. In contrast to physiological traits, leaf metabolite concentrations revealed drought stress before it was visible to the naked eye. We used full-spectrum leaf reflectance data to predict metabolite concentrations using partial least-squares regression, with validation R2 values of 0.49-0.87. We show for the first time that spectroscopy may be used for the quantitative estimation of proline and abscisic acid, demonstrating the first use of hyperspectral data to detect a phytohormone. We used linear discriminant analysis and partial least squares discriminant analysis to differentiate between watered plants and those subjected to drought based on measured traits (accuracy: 71%) and raw spectral data (66%). Finally, we validated our glasshouse-developed models in an independent field trial. We demonstrate that spectroscopy can detect drought stress via underlying biochemical changes, before visual differences occur, representing a powerful advance for measuring limitations on yield.

Plant phenotyping relevance

葉のハイパースペクトル反射から植物の干ばつストレスおよび関連形質を推定する手法を開発・検証しており、独立圃場試験での検証も含むため、表現型取得法が中心である。

Code and data availability

The authors deposited the full raw hyperspectral/phenotype dataset on EcoSIS (DOI 10.21232/UTK8zaW4.669) and the supplementary dataset containing raw gas exchange and leaf metabolic trait data (DOI 10.21232/UTK8zaW4.665). Both are public, paper-specific phenotype/spectral datasets directly reproducing the paper's PLSR/