Long‐term measurements of chlorophyll a fluorescence using the JIP‐test show that combined abiotic stresses influence the photosynthetic performance of the perennial ryegrass (Lolium perenne) in a managed temperate grassland |
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| Authors: | Anthony Digrado Aurélie Bachy Ahsan Mozaffar Niels Schoon Filippo Bussotti Crist Amelynck Anne‐Catherine Dalcq Marie‐Laure Fauconnier Marc Aubinet Bernard Heinesch Patrick du Jardin Pierre Delaplace |
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| Affiliation: | 1. Plant Biology Laboratory, AGRO‐BIO‐CHEM, University of Liège‐Gembloux Agro‐Bio Tech, Gembloux, Belgium;2. Biosystems Dynamics and Exchanges, TERRA, University of Liège‐Gembloux Agro‐Bio Tech, Gembloux, Belgium;3. Royal Belgian Institute for Space Aeronomy, Uccle, Belgium;4. Department of Agri‐Food Production and Environmental Science, University of Florence, Florence, Italy;5. Department of Analytical Chemistry, Ghent University, Ghent, Belgium;6. Modeling and Development Unit, AGRO‐BIO‐CHEM, University of Liège‐Gembloux Agro‐Bio Tech, Gembloux, Belgium;7. Agro‐Bio Systems Chemistry, TERRA, University of Liège‐Gembloux Agro‐Bio Tech, Gembloux, Belgium |
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| Abstract: | Several experiments have highlighted the complexity of stress interactions involved in plant response. The impact in field conditions of combined environmental constraints on the mechanisms involved in plant photosynthetic response, however, remains understudied. In a long‐term field study performed in a managed grassland, we investigated the photosynthetic apparatus response of the perennial ryegrass (Lolium perenne L.) to environmental constraints and its ability to recover and acclimatize. Frequent field measurements of chlorophyll a fluorescence (ChlF) were made in order to determine the photosynthetic performance response of a population of L. perenne. Strong midday declines in the maximum quantum yield of primary photochemistry (FVFM) were observed in summer, when a combination of heat and high light intensity increased photosynthetic inhibition. During this period, increase in photosystem I (PSI) activity efficiency was also recorded, suggesting an increase in the photochemical pathway for de‐excitation in summer. Strong climatic events (e.g. heat waves) were shown to reduce electron transport between photosystem II (PSII) and PSI. This reduction might have preserved the PSI from photo‐oxidation. Periods of low soil moisture and high levels of sun irradiance increased PSII sensitivity to heat stress, suggesting increased susceptibility to combined environmental constraints. Despite the multiple inhibitions of photosynthetic functionality in summer, the L. perenne population showed increased PSII tolerance to environmental stresses in August. This might have been a response to earlier environmental constraints. It could also be linked to the selection and/or emergence of well‐adapted individuals. |
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