Depolarizing metrics for plant samples imaging

PLoS One. 2019 Mar 14;14(3):e0213909. doi: 10.1371/journal.pone.0213909. eCollection 2019.

Abstract

Optical methods, as fluorescence microscopy or hyperspectral imaging, are commonly used for plants visualization and characterization. Another powerful collection of optical techniques is the so-called polarimetry, widely used to enhance image contrast in multiple applications. In the botanical applications framework, in spite of some works have already highlighted the depolarizing print that plant structures left on input polarized beams, the potential of polarimetric methods has not been properly exploited. In fact, among the few works dealing with polarization and plants, most of them study light scattered by plants using the Degree of Polarization (DoP) indicator. Other more powerful depolarization metrics are nowadays neglected. In this context, we highlight the potential of different depolarization metrics obtained using the Mueller matrix (MM) measurement: the Depolarization Index and the Indices of Polarimetric Purity. We perform a qualitative and quantitative comparison between DoP- and MM-based images by studying a particular plant, the Hedera maroccana. We show how Mueller-based metrics are generally more suitable in terms of contrast than DoP-based measurements. The potential of polarimetric measurements in the study of plants is highlighted in this work, suggesting they can be applied to the characterization of plants, plant taxonomy, water stress in plants, and other botanical studies.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Botany / instrumentation
  • Botany / methods*
  • Botany / statistics & numerical data
  • Hedera / anatomy & histology
  • Light
  • Microscopy, Polarization / methods
  • Optical Imaging / methods
  • Plant Leaves / anatomy & histology
  • Plants / anatomy & histology*
  • Scattering, Radiation

Grants and funding

This research was supported by the Spanish MINECO (FIS2015-66328-C3-1-R, FIS2015-66328-C3-3-R and fondos FEDER, all to JC); Catalan Government (SGR 2014-1639 to JC). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.