TY - JOUR
T1 - Effects of growth temperature on photosynthetic gas exchange characteristics and hydraulic anatomy in leaves of two cold-climate Poa species
AU - Medek, Danielle E.
AU - Evans, John R.
AU - Schortemeyer, Marcus
AU - Ball, Marilyn C.
N1 - Publisher Copyright:
© CSFRO 2011.
PY - 2011
Y1 - 2011
N2 - How plastic is hydraulic anatomy with growth temperature, and how docs this relate to photosynthesis? These interrelationships were studied in subantarctic Poafoliosa Hook. f. and alpine Poa hothamensis Vickcry grown under 7/4°C and 12/9°C day/night temperatures, reflecting summer temperatures in their respective habitats. Conduit radii were smaller in P.foliosa than in P. hothamensis, consistent with greater avoidance of frccze/thaw-induced embolism. Despite its origins in an environment with relatively little temperature variation, P. foliosa exhibited greater plasticity in hydraulic anatomy than P. hothamensis, increasing the size and density of conduits when grown under the warmer temperature regime. Both species had similar anatomical capacities for water transport when grown at 12/9°C, but stomatal conductance was lower in P.foliosa than P. hothamensis, suggesting hydraulic limitations not explained by leaf vascular anatomy. However, greater photosynthetic capacity and foliar nitrogen contents enabled P.foliosa to achieve the same assimilation rate as P. hothamensis under the 12/9°C growth conditions. Our results showed that nitrogen plays a central role in maintaining assimilation rates when constrained cither by enzymatic activity at low temperatures or by hydraulic limitations at high temperatures and evaporative demands. Interspecific differences in nitrogen and water use may influence how subantarctic and alpine vegetation responds to climate wanning.
AB - How plastic is hydraulic anatomy with growth temperature, and how docs this relate to photosynthesis? These interrelationships were studied in subantarctic Poafoliosa Hook. f. and alpine Poa hothamensis Vickcry grown under 7/4°C and 12/9°C day/night temperatures, reflecting summer temperatures in their respective habitats. Conduit radii were smaller in P.foliosa than in P. hothamensis, consistent with greater avoidance of frccze/thaw-induced embolism. Despite its origins in an environment with relatively little temperature variation, P. foliosa exhibited greater plasticity in hydraulic anatomy than P. hothamensis, increasing the size and density of conduits when grown under the warmer temperature regime. Both species had similar anatomical capacities for water transport when grown at 12/9°C, but stomatal conductance was lower in P.foliosa than P. hothamensis, suggesting hydraulic limitations not explained by leaf vascular anatomy. However, greater photosynthetic capacity and foliar nitrogen contents enabled P.foliosa to achieve the same assimilation rate as P. hothamensis under the 12/9°C growth conditions. Our results showed that nitrogen plays a central role in maintaining assimilation rates when constrained cither by enzymatic activity at low temperatures or by hydraulic limitations at high temperatures and evaporative demands. Interspecific differences in nitrogen and water use may influence how subantarctic and alpine vegetation responds to climate wanning.
KW - A-C<inf>i</inf> curve
KW - Cold tolerance
KW - Macquarie island
UR - http://www.scopus.com/inward/record.url?scp=80051977197&partnerID=8YFLogxK
U2 - 10.1071/FP10023
DO - 10.1071/FP10023
M3 - Article
SN - 1445-4408
VL - 38
SP - 54
EP - 62
JO - Functional Plant Biology
JF - Functional Plant Biology
IS - 1
ER -