Acclimation of tomato to different carbon dioxide concentrations. Relationships between biochemistry and gas exchange during leaf development

summary Tomato plants were transferred to different CO 2 mole fractions (350, 700, 1050 and 1400μmol CO 2 mol −1 ) 31 d after sowing (2% of full expansion) and the light saturated rate of photosynthesis ( P max ) of the unshaded 5th leaf was measured at either an ambient CO 2 mole fraction, C 2 of 350 μmol CO 2 mol −1 ( P max (350)) or at the mole fraction of CO 2 at which the plants were grown. At 60% nd 95% leaf expansion, P max of high CO 2 grown plants measured at growth CO 2 , was greater than the P max (350) of the ambient CO 2 grown plants. However, by leaf maturity, P max (growth CO 2 ) declined linearly as growth CO 2 concentration increased. P max (350) of plants exposed to elevated CO 2 up to 60% le f expansion had not acclimated to high CO 2 At 95% leaf expansion, P max (350) was smaller in the high CO 2 grown plants. P max (350) w s predicted from Rubisco in vitro carboxylation capacity using tomato Rubisco kinetic constants. By 95% leaf expansion, high CO 2 grown plants showed similarities to the response of plants to low nitrogen supply, in terms of Rubisco nd chlorophyll content. The observed nd theoretical relationships between the initial slopes of the P max /C 1 responses nd Rubisco activity were statistically equivalent. Both short‐term and long‐term effects of elevated CO 2 on dark respiration ( R n ) were also investigated at two stages of leaf development (50 nd 100% expansion). R n (growth CO 2 ) was smaller for the high CO 2 grown plants compared with the control plants, whereas R n (350) was either equal or greater for the plants grown in high CO 2