Using combined measurements of gas exchange and chlorophyll fluorescence to estimate parameters of a biochemical C₃ photosynthesis model: a critical appraisal and a new integrated approach applied to leaves in a wheat ( Triticum aestivum) canopy

XINYOU YIN; STRUIK, PAUL C.; ROMERO, PASCUAL; HARBINSON, JEREMY; EVERS, JOCHEM B.; VAN DER PUTTEN, PETER E. L.; VOS, JAN

We appraised the literature and described an approach to estimate the parameters of the Farquhar, von Caemmerer and Berry model using measured CO2 assimilation rate ( A) and photosystem II (PSII) electron transport efficiency ( Φ2). The approach uses curve fitting to data of A and Φ2 at various levels of incident irradiance ( Iinc), intercellular CO2 ( Ci) and O2. Estimated parameters include day respiration ( Rd), conversion efficiency of Iinc into linear electron transport of PSII under limiting light [ κ2(LL)], electron transport capacity ( Jmax), curvature factor ( θ) for the non-rectangular hyperbolic response of electron flux to Iinc, ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) CO2/O2 specificity ( Sc/o), Rubisco carboxylation capacity ( Vcmax), rate of triose phosphate utilization ( Tp) and mesophyll conductance ( gm). The method is used to analyse combined gas exchange and chlorophyll fluorescence measurements on leaves of various ages and positions in wheat plants grown at two nitrogen levels. Estimated Sc/o (25 °C) was 3.13 mbar µbar−1; Rd was lower than respiration in the dark; Jmax was lower and θ was higher at 2% than at 21% O2; κ2(LL), Vcmax, Jmax and Tp correlated to leaf nitrogen content; and gm decreased with increasing Ci and with decreasing Iinc. Based on the parameter estimates, we surmised that there was some alternative electron transport.

CHLOROPHYLL; CHLOROPLAST pigments; PORPHYRINS; TETRAPYRROLES; WHEAT; GRASSES; GASES from plants

Plant, Cell & Environment, 2009, Vol 32, Issue 5, p448

0140-7791

Academic Journal

10.1111/j.1365-3040.2009.01934.x