Increased capacity for photosynthesis in wheat grown at elevated CO2: the relationship between electron transport and carbon metabolism
✍ Scribed by Dimah Z. Habash; Matthew J. Paul; Martin A. J. Parry; Alfred J. Keys; David W. Lawlor
- Book ID
- 104659283
- Publisher
- Springer-Verlag
- Year
- 1995
- Tongue
- English
- Weight
- 882 KB
- Volume
- 197
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Spring wheat (Triticum aestivum L.) was grown under optimal nutrition for six weeks at 700 and 350 gmol.mol-t CO2 and simultaneous measurements of photosystem-II (PSII) chlorophyll fluorescence and gas exchange were conducted on intact attached leaves. Plants grown at elevated COs had double the concentration of CO2 at the carboxylation site (C~) despite a lowered stomatal (gs) and mesophyll (gm) conductance compared with ambient-grown plants. Plants grown at elevated CO2 had a higher relative quantum yield of PSII electron transport (qSpsn) and a higher relative quantum yield of CO2 fixation (~co2). The higher (I)Psll was due to a larger proportion of open PSII centres, estimated by the coefficient of photochemical quenching of fluorescence (qp), with no change in the efficiency of light harvesting and energy transduction by open PSII centres (F'v/F~). Analysis of the relationship between ~PsH and ~co2 conducted under various CO2 and 02 concentrations showed that the higher @co2 for a given (I)Psli in leaves developed under elevated CO2was similar to that obtained in leaves upon a partial reduction in photorespiration. Calculation of the allocation of photosynthetic electron-transport products to COz and 02 showed that for leaves developed in elevated CO2, there