UV fluorescence as a way to assess plant health

Leaves will fluoresce red under UV light. The fluorescence directly indicates the amount of chlorophyll in each part of the plant. This has been used as a way to assess plant health.

Wikipedia:
- Chlorophyll fluorescence
- Kautsky effect
- Chlorophyll a
- Fluorometer
- after measurements are taken from a fluorometer, someone might try to analyze:
  - Photosynthetic efficiency (Ctrl-F for "fluorescence")
  - Light-harvesting complex (LHC)
  - Photosystem I (PSI) and Photosystem II (PSII) (more general: photosystem)
  - Non-photochemical quenching (NPQ)
Murchie, Erik H., and Tracy Lawson. "Chlorophyll fluorescence analysis: a guide to good practice and understanding some new applications." Journal of experimental botany 64.13 (2013): 3983-3998.
Park, Beomjin, et al. "Chlorophyll fluorescence imaging for environmental stress diagnosis in crops." Sensors 24.5 (2024): 1442.

Fluorescence transient curves:

Mathur, Sonal, et al. "Chlorophyll fluorescence is a potential indicator to measure photochemical efficiency in early to late soybean maturity groups under changing day lengths and temperatures." Frontiers in Plant Science 14 (2023): 1228464.

"Soybean leaves exhibited a polyphasic rise called the O–J–I–P fluorescence transient. We determined the effects of temperatures and day lengths on different maturity groups based on the transient shape. Each maturity group has a group-specific shape of fluorescence transient (OJIP), which is convenient for phenotyping that makes them specific to identify. Any alteration in the photosynthetic apparatus will change the shape of the transient for that maturity group."

("MG 0", "MG III", "MG IX", and "MG X" refer to different maturity groups)

Kolber, Zbigniew; Klimov, Denis; Ananyev, Gennady; Rascher, Uwe; Berry, Joseph; Osmond, Barry (June 2005). "Measuring photosynthetic parameters at a distance: laser induced fluorescence transient (LIFT) method for remote measurements of photosynthesis in terrestrial vegetation". Photosynthesis Research. 84 (1–3): 121–129. Bibcode:2005PhoRe..84..121K. doi:10.1007/s11120-005-5092-1. ISSN 0166-8595. PMID 16049764. S2CID 26721484.
Dudeja, S. S., Chaudhary, P. (2005). Fast chlorophyll fluorescence transient and nitrogen fixing ability of chickpea nodulation variants. Photosynthetica 43 (2), 253–259. doi: 10.1007/s11099-005-0041-y
Pieruschka, Roland; Klimov, Denis; Berry, Joseph A.; Osmond, C. Barry; Rascher, Uwe; Kolber, Zbigniew S. (2012), Normanly, Jennifer (ed.), "Remote Chlorophyll Fluorescence Measurements with the Laser-Induced Fluorescence Transient Approach", High-Throughput Phenotyping in Plants: Methods and Protocols, Methods in Molecular Biology, vol. 918, Totowa, NJ: Humana Press, pp. 51–59, doi:10.1007/978-1-61779-995-2_5, ISBN 978-1-61779-995-2, PMID 22893285, retrieved 2022-10-25
Desotgiu, Rosanna, et al. "Chlorophyll a fluorescence analysis along a vertical gradient of the crown in a poplar (Oxford clone) subjected to ozone and water stress." Tree Physiology 32.8 (2012): 976-986.

Details of photosynthesis:

"electrons are transferred from water to NADP via three major transmembrane complexes: Photosystem II (PSII), the cytochrome b6f complex (cyt bf), and photosystem I (PSI)"
- This article does refer to "δRo presents the efficacy or capability by which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors (Snider et al., 2018). δR0 is dependent on electrons transferred from PQH₂ to PSI."

Commercial chlorophyll fluorometers: