
TY  - JOUR
A1  - Hogan, KP 
A1  - Whitehead, D 
A1  - Kallarackal, J 
A1  - Buwalda, JG 
A1  - Meekings, J 
A1  - Rogers, GND 
T1  - Photosynthetic Activity of Leaves of <I>Pinus radiata</I> and <I>Nothofagus fusca</I> After 1 Year of Growth at Elevated CO<sub>2</sub>
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1996
VL  - 23
IS  - 5
SP  - 623
EP  - 630
KW  - acclimation, downregulation, senescence, stomatal conductance
UR  - https://doi.org/10.1071/PP9960623 
N2  - Radiata pine (Pinus radiata D.Don) and red beech (Nothofagus fusca (Hook. f.) Oerst.) were grown for over 1 year at elevated (ELEV, 64 Pa) and ambient (AMB, 38 Pa) CO2 partial pressure in open-top chambers. Springtime measurements of overwintering leaves showed that light- and CO2-saturated photosynthetic rates (Amax) of pine leaves were similar for the two treatments (AMB: 6.7 ± 1.08 &#956;mol m-2 s-1, mean ± 1 s.e.; ELEV: 6.6 ± 0.47) but, for beech leaves, Amax was greater for AMB plants (8.8 ± 0.90 &#956;mol m-2 s-1) than for ELEV plants (6.10 ± 0.71). Summertime measurements of leaves grown that spring showed that for pine, Amax was similar in the two CO2 treatments (AMB 14.9 &#956;mol m-2 s-1 ± 0.80; ELEV: 13.5 ± 1.9) while, for beech, Amax was higher in AMB plants (21.0 ± 1.1) than in ELEV plants (17.2 ± 1.9), although the difference was not statistically significant. These results indicate downregulation of photosynthetic capacity of beech but not pine. Vcmax did not differ between treatments within species, suggesting that there was no acclimation of rubisco activity. Triose phosphate utilisation limitation may have contributed to the downregulation of Amax in beech. For pine, photosynthesis at treatment CO2 partial pressures was greater in ELEV plants in both spring and summer. For beech measured at treatment CO2 partial pressures, photosynthesis was greater in ELEV plants in summer, but was similar between treatments in the springtime. 
ER  -

