Essential tool for precision farming: New method for photochemical reflectance index measurement

phys.org | 7/20/2018 | Staff
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Precision farming, which relies on spatially heterogeneous application of fertilizers, biologically active compounds, pesticides, etc., is one of the leading trends in modern agricultural science.

A necessary condition for such farming is quick remote analysis of the state of plants in the fields and greenhouses. To solve this problem, various spectral indices based on measurements of reflected light in narrow spectral bands are widely used. One of these indices, currently the focus of Lobachevsky University researchers, is the photochemical reflectance index—PRI.

Reflectance - Index - Wavelengths - Range - Nm

The photochemical reflectance index is determined by measuring reflected light at two wavelengths in the yellow-green spectral range, at 531 and 570 nm, which is carried out using special detectors or multispectral cameras.

"A unique feature of the photochemical reflectance index is its sensitivity even to weak, stress-related changes in the state of the photosynthetic apparatus. This opens up the potential possibility of using the photochemical reflectance index for early and remote diagnosis of how adverse factors may affect plants. However, the use of PRI has a number of serious limitations, one of them being the high sensitivity of the index to the lighting conditions, which is especially important if the measurements take place under solar lighting conditions," says Vladimir Sukhov, head of the UNN plant electrophysiology laboratory.

Problem - Research - Project - Ekaterina - Sukhova

This problem is addressed in the research project carried out by Ekaterina Sukhova, graduate student at the Department of Biophysics Lobachevsky University. The project was supported by the Russian Science Foundation (project No. 17-76-20032, supervisor Vladimir Sukhov). Research results were published in Remote Sensing.

For this purpose, Lobachevsky University scientists proposed an idea that could potentially reduce the sensitivity of the photochemical reflectance index to lighting conditions. It is based on the use of periodic illumination of the plant by pulses of yellow-green measuring light from a source with known spectral characteristics.

Intensity

The intensity of the reflected...
(Excerpt) Read more at: phys.org
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