Optical monitoring of the plant growth status using polarimetry

Abstract

Polarimetry is a powerful characterization technique that uses a wealth of information from electromagnetic waves, including polarization. Using the rich information provided by polarimetry, it is being actively studied in biomedical fields such as cancer and tumor diagnosis. Despite its importance and potential in agriculture, polarimetry for living plants has not been well studied. A Stokes polarimetric imaging system was built to determine the correlation between the polarization states of the light passing through the leaf and the growth states of lettuce. The Stokes parameter s3 associated with circular polarization increased over time and was strongly correlated with the growth of lettuce seedlings. In the statistical analysis, the distribution of s3 followed the generalized extreme value (GEV) probability density function. Salt stress retarded plant growth, and the concentration of treated sodium chloride (NaCl) showed a negative correlation with the location parameter μ of GEV. The clear correlation reported here will open the possibility of polarization measurements on living plants, enabling real-time monitoring of plant health.

Mueller-Polarimetry of Barley Leaves I: Depolarization Metrics

“…The application of polarimetric methods to the study of botanical samples has a rather extensive history (see, for example, [2][3][4][5][6]). To date, a number of very interesting results have been obtained in this context but primarily limited to the use of the degree of polarization (DoP) of light reflected by plants [7][8][9][10]. The summary from past work is that the DoP for botanical samples depends on the state of polarization of the incident light.…”