Photosynthesis-irradiance response at physiological level: A mechanistic model

Han, BP

Bp. Han, Photosynthesis-irradiance response at physiological level: A mechanistic model, J THEOR BIO, 213(2), 2001, pp. 121-127

31

INGLESE

Article

Multidisciplinary

JOURNAL OF THEORETICAL BIOLOGY

0022-5193 → ACNP

213

2

2001

121 - 127

ISI

0022-5193(20011121)213:2<121:PRAPLA>2.0.ZU;2-E

A mechanistic model is developed to present the photosynthetic response of phytoplankton to irradiance at the physiological level. The model is operat ed on photosynthetic units (PSU), and each PSU is assumed to have two state s: reactive and activated. Light absorption that drives a reactive PSU into the activated state results from the effective absorption of the PSU. Tran sitions between the two states are asymmetrical in rate. A PSU in the react ive state becomes activated much faster than it recovers from the activated state to the reactive one. The turnover time for an activated PSU to trans it into the reactive one is defined by the turnover time of the electron tr ansport chain. The present model yields a photosynthesis-irradiance curve ( PE-curve) in a hyperbola, which is described by three physiological paramet ers: effective cross-section (sigma (PSII)), turnover time of electron tran sport chain (tau) and number of PSUs (N). The PE-curve has an initial slope of sigma (PSII) x N, a half-saturated irradiance of 1/(sigma (PSII)), and a maximal photosynthetic rate of Nlc at the saturated irradiance. The PE-cu rve from the present model is comparable to the empirical function based on the target theory described by the Poisson distribution. (C) 2001 Academic Press.