Preface to the 1st edition
In this handbook we discuss methods relevant to research on the responses of plants to ultraviolet () radiation. We also summarize the knowledge needed to make informed decisions about manipulation and quantification of radiation, and the design of experiments. We give guidelines and practical recommendations for obtaining reliable and relevant data and interpretations. We cover research both on terrestrial and aquatic plants (seaweeds, marine angiosperms and freshwater higher plants are included, but microalgae are excluded from the scope of this work). We consider experimentation on ecological, eco-physiological and physiological questions.
The handbook will be most useful to early stage researchers (ESRs). However, more experienced researchers will also find information of interest. The guidelines themselves, we hope, will ensure a high and uniform standard of quality for research within our COST action, and the whole research community. We have written this text so that it is useful both for reading from cover to cover and for reference. It will also be useful as a textbook for training workshops aimed at ESRs.
Physiological and eco-physiological experiments can attempt to respond to different objective questions: (1) will a future increase in radiation affect growth and morphology of plants? (2) what is the effect of current radiation levels on plant growth and morphology? (3) what are the mechanisms by which plants respond to radiation? Ecological experiments can have other objectives, e.g. (1) does radiation in sunlight affect plant fitness? (2) does a differential effect of radiation between plant species affect the outcome of competition? (3) does the exposure to radiation alter plant-pathogen and plant-herbivore interactions? Finally applied research related to agricultural and horticultural production and produce is based on questions like: (1) can manipulations of radiation be used to manage produce quality? (2) can manipulation of radiation replace the use of pesticides and growth regulators? The approach suitable for a given experiment will depend on its objectives.
When doing experiments with terrestrial plants, the medium surrounding the stems and leaves is air. At short path lengths air has little influence on irradiance and only when considering the whole depth of the atmosphere, its transmittance needs to be taken into account. In contrast, water and impurities like dissolved organic matter (DOM) absorb radiation over relatively short path lengths, which means that in water bodies irradiance decreases with depth. Basic concepts of photobiology, radiation physics and in the natural environment of plants are discussed in chapter 7.
Varied approaches are used in the study of the effects of radition on plants. The main dichotomy is whether (1) radiation is added by means of special lamps to either sunlight or to visible light from other lamps, or (2) radiation in sunlight is excluded or attenuated by means of filters. Both approaches are extensively discussed in chapter 8.
For any experimental approach used in research we need to quantify radiation and express it as meaningful physical quantities that allow comparison among experiments and to natural conditions. When comparing irradiance from sources differing in spectral composition, the comparison requires the calculation of biologically effective doses. Quantification of radiation is discussed in chapter 9. The appendices present in detail the calculations needed when measuring action spectra, and for calculating biologically effective doses both with Excel and R. An R package which facilitates such calculations accompanies this handbook, and will be made available through CRAN (the Comprehensive R Archive Network) and the handbook’s web pages at http://uv4growth.dyndns.org.
Both for terrestrial and aquatic plants the enclosing materials should be carefully chosen based on their transmittance and reflectance properties. This is crucial in research, but also in any other research with plants using an enclosing structure such as open-top chambers (OTC), greenhouses or aquaria. These and many other considerations about the cultivation of plants are discussed in chapter 10.
Only experiments well designed from the statistical point of view, allow valid conclusions to be reached. In addition a valid statistical analysis of the data, consistent with the design of the experiment and based on as few assumptions as possible, is required. Well designed experiments are also efficient in the use of resources (both time and money). The design of experiments and the analysis of the data obtained are discussed in chapter 11.
Finally a few words about terminology. As the same quantities and units are used for measuring visible, and ultraviolet radiation, throughout the book we use the word “radiation” to refer to both visible and ultraviolet radiation. We prefer “radiation” to “light”, since light is sometimes, but not always, used for just the portion of the electromagnetic spectrum visible to humans.
In the PDF file all links and crossreferences are ‘live’: just click on them to navigate through the file. They are marked by coloured boxes in the viewer but these boxes are not printed. In the list of references DOIs and URLs are also hyperlinked.
If you find mistakes, or difficult to understand passages, or have suggestions on how to improve this handbook, please, send feedback directly to the lead editor at mailto:pedro.aphalo@helsinki.fi?subject=UV Handbook Edition01.
The PDF file can be freely distributed and the latest version will be available from the handbook web page at http://uv4growth.dyndns.org/. Printed copies can be obtained from http://www.amazon.co.uk, http://www.amazon.de or http://www.amazon.com.
Helsinki,Pedro J. Aphalo
München,Andreas Albert
Lund,Lars Olof Björn
Edinburgh,Andy McLeod
Helsinki,T. Matthew Robson
Copenhagen,Eva Rosenqvist
October 2012
Acknowledgements
The writing and publication of this book was made possible by COST Action FA0906 ‘UV4growth’. This book is a collaborative effort of all members of the technical group on technology of this action, plus four authors not participating in the Action. The first conference and workshop organized by the Action in Szeged, Hungary, put the authors in contact as well as allowing them to realise that a book on research methods was needed. Some of the authors met again in Denmark, and spent two and a half days of intense writing and discussions thanks to the hospitality of Eva Rosenqvist and Carl-Otto Ottosen. We thank Profs. Åke Strid and Donat Häder for reading the whole manuscript and giving numerous suggestions for improvement.
A preprint of this handbook was used in a training school organised by the COST action at the University of Málaga (16–18 April, 2012). Corrections of errors, suggestions for improvement and complains about difficult to understand passages from participants are acknowledged.
We thank Avantes (The Netherlands), BioSense (Germany), Biospherical Instruments Inc. (U.S.A.), Delta-T Devices Ltd. (U.K.), EIC (Equipos Intrumentación y Control) (Spain), Gooch & Housego (U.S.A.), Kipp & Zonen B.V. (The Netherlands), Ocean-Optics (The Netherlands), Valoya Oy (Finland) Skye Instruments Ltd. (U.K.), TriOS Mess- und Datentechnik GmbH (Germany) and Yankee Environmental Systems, Inc. (U.S.A.) for providing illustrations. We thank Prof. Donat Häder for supplying the original data used to draw two figures and photographs of the ELDONET instrument. We thank Dr. Ulf Riebesell and Jens Christian Nejstgaard for photographs.
This work was funded by COST. Pedro J. Aphalo acknowledges the support of the Academy of Finland (decisions 116775 and 252548). Félix López Figueroa acknowledges the support by the Ministry of Innovation and Science of Spain (Project CGL08-05407-C03-01). Andy McLeod acknowledges the support of a Royal Society Leverhulme Trust Senior Research Fellowship and research awards from the Natural Environment Research Council (U.K.). Iván Gómez and Pirjo Huovinen acknowledge the financial support by CONICYT (Chile) through grants Fondecyt 1090494, 1060503 and 1080171.