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
Hauptverfasser: Rho, H.M., Seoul National University, Seoul, Republic of Korea, Yu, D.J., Seoul National University, Seoul, Republic of Korea, Kim, S.J., Seoul National University, Seoul, Republic of Korea, Chun, C.H., Seoul National University, Seoul, Republic of Korea, Lee, H.J., Seoul National University, Seoul, Republic of Korea
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Sprache:eng
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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.
ISSN:2211-3452
2211-3460
DOI:10.1007/s13580-011-0035-6