Tuesday, 04 August 2015 23:57

How do you spell light?

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Characterizing spectral properties and calculating irradiances are everyday tasks for many researchers in the field of plant photobiology. Varying waveband definitions in use, different photoreceptors found in plants, let alone the difference between expressing light on photon or energy basis can make one’s head spin. To tackle this, a couple of publications and an application are highly recommendable.

Starting from nature of light and its interaction with matter, going through biological light perception and regulation and evolution of photosynthesis; all this and a myriad of another topics, can all be found in the latest edition of ”Photobiology: Science of Life and Light” (edited by Lars Olof Björn).

Beyond the Visible: A handbook of best practice in plant UV photobiology (edited by Pedro J. Aphalo et al.) offers a knowledge base for methods for research on the responses of plants to ultraviolet radiation, dealing with experimentation on ecological, eco-physiological and physiological questions (practical recommendations for obtaining reliable and relevant data and interpretations can be applied beyond UV!).

Then for the application: Have you ever been wondering how nice it would be to easily maneuver between the energy irradiance (W m-2) and photon irradiance (mol m-2 s-1) calculations? Or how to calculate spectral properties quickly, check the R:FR ratio etc. Or how to easily determine doses that are especially important when doing experiments with supplemental UV-B radiation? Creating informative graphs, highlighting wavebands? Well look no further, Photobiology packages for R, compiled by Pedro J. Aphalo, are here. The packages are documented in pedantic detail and user guides give ample instructions and examples. Please see below an example graph of sun spectrum and annotations for selected wavebands (UV-B and UV-A according to ISO, far-red according to Sellaro et al.).

Rplot sun blog


ISO (2007) Space environment (natural and artificial) - Process for determining solar irradiances. ISO Standard 21348. ISO, Geneva.

ISO/CIE 17166:1999, Erythema reference action spectrum and standard erythema dose.

Sellaro, R., Crepy, M., Trupkin, S. A., Karayekov, E., Buchovsky, A. S., Rossi, C., & Casal, J. J. (2010). Cryptochrome as a sensor of the blue/green ratio of natural radiation in Arabidopsis. Plant Physiology, 154(1), 401-409. doi:10.1104/pp.110.160820.

Last modified on Wednesday, 05 August 2015 00:05
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