Premium
Thermal acclimation of photosynthesis in black spruce [ Picea mariana (Mill.) B.S.P.]
Author(s) -
WAY DANIELLE A.,
SAGE ROWAN F.
Publication year - 2008
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2008.01842.x
Subject(s) - rubisco , photosynthesis , acclimatization , black spruce , respiration , botany , horticulture , biology , zoology , chemistry , ecology , taiga
We investigated the thermal acclimation of photosynthesis and respiration in black spruce seedlings [ Picea mariana (Mill.) B.S.P.] grown at 22/14 °C [low temperature (LT)] or 30/22 °C [high temperature (HT)] day/night temperatures. Net CO 2 assimilation rates ( A net ) were greater in LT than in HT seedlings below 30 °C, but were greater in HT seedlings above 30 °C. Dark and day respiration rates were similar between treatments at the respective growth temperatures. When respiration was factored out of the photosynthesis response to temperature, the resulting gross CO 2 assimilation rates ( A gross ) was lower in HT than in LT seedlings below 30 °C, but was similar above 30 °C. The reduced A gross of HT seedlings was associated with lower needle nitrogen content, lower ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) maximum carboxylation rates ( V cmax ) and lower maximum electron transport rates ( J max ). Growth treatment did not affect V cmax : J max . Modelling of the CO 2 response of photosynthesis indicated that LT seedlings at 40 °C might have been limited by heat lability of Rubisco activase, but that in HT seedlings, Rubisco capacity was limiting. In sum, thermal acclimation of A net was largely caused by reduced respiration and lower nitrogen investments in needles from HT seedlings. At 40 °C, photosynthesis in LT seedlings might be limited by Rubisco activase capacity, while in HT seedlings, acclimation removed this limitation.