The Kok effect in Vicia faba cannot be explained solely by changes in chloroplastic CO2 concentration
© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
| Publié dans: | The New phytologist. - 1979. - 216(2017), 4 vom: 15. Dez., Seite 1064-1071 |
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| Auteur principal: | |
| Autres auteurs: | , |
| Format: | Article en ligne |
| Langue: | English |
| Publié: |
2017
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| Accès à la collection: | The New phytologist |
| Sujets: | Journal Article Kok effect dark respiration light respiration photorespiration photosynthesis Carbon Dioxide 142M471B3J |
| Résumé: | © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust. The Kok effect - an abrupt decline in quantum yield (QY) of net CO2 assimilation at low photosynthetic photon flux density (PPFD) - is widely used to estimate respiration in the light (R), which assumes the effect is caused by light suppression of R. A recent report suggested much of the Kok effect can be explained by declining chloroplastic CO2 concentration (cc ) at low PPFD. Several predictions arise from the hypothesis that the Kok effect is caused by declining cc , and we tested these predictions in Vicia faba. We measured CO2 exchange at low PPFD, in 2% and 21% oxygen, in developing and mature leaves, which differed greatly in R in darkness. Our results contradicted each of the predictions based on the cc effect: QY exceeded the theoretical maximum value for photosynthetic CO2 uptake; QY was larger in 21% than 2% oxygen; and the change in QY at the Kok effect breakpoint was unaffected by oxygen. Our results strongly suggest the Kok effect arises largely from a progressive decline in R with PPFD that includes both oxygen-sensitive and -insensitive components. We suggest an improved Kok method that accounts for high cc at low PPFD |
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| Description: | Date Completed 31.07.2018 Date Revised 30.09.2020 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1469-8137 |
| DOI: | 10.1111/nph.14775 |