Volume 134, Issue 2 p. 317-325
Free Access

Effects of leaf age, basal meristem and infection with powdery mildew on photosynthesis in barley grown in 700 μmol mol−1CO2

J. M. HIBBERD

Corresponding Author

J. M. HIBBERD

1To whom correspondence should be addressed at present address: Robert Hill Institute, Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, UK. E-mail: [email protected]Search for more papers by this author
P. RICHARDSON

P. RICHARDSON

School of Biological Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, UK

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R. WHITBREAD

R. WHITBREAD

School of Biological Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, UK

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J. F. FARRAR

J. F. FARRAR

School of Biological Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, UK

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First published: October 1996
Citations: 23

summary

The rate of net photosynthesis in the second leaf of barley was higher in 700 than 350 μmol mol−1CO2, when measured in the CO2 concentration in which the plants were grown, but the magnitude of this difference decreased as the leaf aged. Infection by powdery mildew accelerated the decline in net photosynthesis of leaves grown in either 350 or 700 μmol mol−1CO2. A/Ci curves allowed the reduction in net photosynthesis of plants exposed to 700 μmol mol−1CO2 or after infection by powdery mildew to be related to changes in the carboxylation efficiency or in the regeneration of ribulose 1,5-bisphosphate. The carboxylation efficiency declined in plants exposed to 700 μmol mol−1CO2. In plants infected with powdery mildew, the reduction in net photosynthesis was associated with both reduced carboxylation efficiency and reduced ability to regenerate ribulose 1,5-bisphosphate. Reduced carboxylation efficiency of the second leaf of plants grown in 700 μmol mol−1CO2, was not associated with a reduction in the concentration of rubisco within the leaf. In contrast to the presence of a close exogenous sink, leaf age had large effects on the acclimation of photosynthesis to 700 μmol mol−1CO2.