Interactive effects of light, leaf temperature, CO2 and O2 on photosynthesis in soybean

Abstract

A biochemical model of C 3photosynthesis has been developed by G.D. Farquhar et al. (1980, Planta 149, 78-90) based on Michaelis-Menten kinetics of ribulose-1,5-bisphosphate (RuBP) carboxylase-oxygenase, with a potential RuBP limitation imposed via the Calvin cycle and rates of electron transport. The model presented here is slightly modified so that parameters may be estimated from whole-leaf gas-exchange measurements. Carbon-dioxide response curves of net photosynthesis obtained using soybean plants (Glycine max (L.) Merr.) at four partial pressures of oxygen and five leaf temperatures are presented, and a method for estimating the kinetic parameters of RuBP carboxylase-oxygenase, as manifested in vivo, is discussed. The kinetic parameters so obtained compare well with kinetic parameters obtained in vitro, and the model fits to the measured data give r (2)values ranging from 0.87 to 0.98. In addition, equations developed by J.D. Tenhunen et al. (1976, Oecologia 26, 89-100, 101-109) to describe the light and temperature responses of measured CO2-saturated photosynthetic rates are applied to data collected on soybean. Combining these equations with those describing the kinetics of RuBP carboxylase-oxygenase allows one to model successfully the interactive effects of incident irradiance, leaf temperature, CO2 and O2 on whole-leaf photosynthesis. This analytical model may become a useful tool for plant ecologists interested in comparing photosynthetic responses of different C3 plants or of a single species grown in contrasting environments.

The Regulation of Rubisco Activity in Response to Variation in Temperature and Atmospheric CO2 Partial Pressure in Sweet Potato

“…Data were calculated using the IS and the CO 2 compensation point in the absence of nonphotorespiratory CO 2 evolution (Brooks and Farquhar, 1985). The solid line is the modeled response of R d according to Harley et al (1985; Farquhar and von Caemmerer (1982), using mean Rubisco activities in Figure 2, the kinetic equations in the Supplemental Appendix, and the measured activation state at 140 mbar C i in Figure 3A. The solid line is the modeled response for the IS using the regression of measured Rubisco V cmax versus temperature (Eq.…”

Improved temperature response functions for models of Rubisco-limited photosynthesis

“…1e & f. Reported values for K c and K o vary considerably at a given temperature (Badger & Collatz 1977;Jordan & Ogren 1984;Harley, Weber & Gates 1985), even though the values for these parameters are expected to remain similar among higher plants et al (1994) are within 1% of each other at 25°C for K c and within 10% for K o (Fig. 1e), even though the two studies used different transgenic strains of tobacco.…”

Effect of Photosynthetic Photon Flux Density on Carboxylation Efficiency

“…The effect of PPFD on the C02-saturated rate of photosynthesis has been observed previously (5,12,24). Some studies have indicated a dependency of OA/dC(F), or CE (10), on PPFD (3, 16); however, few studies have been carried out to define clearly this interaction.…”

“…Thus, the sensitivity of in situ RuBP carboxylase activity to PPFD could be determined indirectly by measuring the variation ofOA/dC(r) with PPFD. In addition, advances in our understanding of the biochemical mechanisms controlling photosynthesis have allowed the development of more accurate models of whole-leaf photosynthesis (9,12) that explicitly include activity of RuBP carboxylase. Comparison of the measured response of 0A/KC(r) to PPFD with simulations using the model (9,12) provided a means of testing the ability of the model to predict the measured response.…”