Estimation of Carboxylation Efficiency from Net CO₂ Assimilation Rate as a Function of Chloroplastic CO₂ Concentration in Strawberry (Fragaria × ananassa cv. Maehyang) Leaves
Carboxylation efficiency in fully expanded leaves of strawberry (Fragaria × ananassa cv. Maehyang) was estimated based on net CO₂ assimilation rate (A∧n) as a function of chloroplastic CO₂ concentration (C∧c). To estimate the mesophyll conductance (g∧m) and then construct A∧n-C∧c curves, A∧n and ele...
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Veröffentlicht in: | Horticulture, environment and biotechnology environment and biotechnology, 2011-12, Vol.52 (6), p.547-552 |
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Zusammenfassung: | Carboxylation efficiency in fully expanded leaves of strawberry (Fragaria × ananassa cv. Maehyang) was estimated based on net CO₂ assimilation rate (A∧n) as a function of chloroplastic CO₂ concentration (C∧c). To estimate the mesophyll conductance (g∧m) and then construct A∧n-C∧c curves, A∧n and electron transport rate as a function of intercellular CO₂ concentration (C∧i) were simultaneously determined at a range of 50 to 2,200 μmol CO₂/mol air at a saturating photosynthetic photon flux (PPF), 1,200 μmolㆍm-²ㆍs-¹. Mitochondrial respiration rate (R∧d) and CO₂ compensation point in the absence of R∧d required for calculating g∧m were found to be 0.15 μmolㆍm-²ㆍs-¹ and 44.1 μmol CO₂/mol air, respectively, as determined from A∧n-C∧i curves below 200 μmol CO₂/mol air at three different PPFs. Both stomatal conductance (g∧s) and g∧m decreased with increasing C∧i. However, the g∧m responded more sensitively to various C∧i than the g∧s. The g∧m was significantly lower than the g∧s at C∧i beyond 600 μmolㆍmol-¹ air examined. Maximum carboxylation efficiency (α∧cmax) derived from A∧n-C∧c curves was 0.28 μmolㆍm-²ㆍs-¹ and 2.2 times higher than that from A∧n-C∧i curve. Since the A∧n-C∧i curve was based on infinite g∧m, the α∧cmax derived from the A∧n-C∧i curve might be underestimated. Actually, g∧m was rather dynamic with changing C∧i and thus a crucial component of the diffusional limitation of A∧n. For estimating photosynthetic characteristics in strawberry leaves more accurately, A∧n-C∧c curve should be constructed in consideration of g∧m, especially for closed plant production systems. |
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ISSN: | 2211-3452 2211-3460 |
DOI: | 10.1007/s13580-011-0035-6 |