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Enhanced assimilation rate and water use efficiency with latitude through increased photosynthetic capacity and internal conductance in balsam poplar ( Populus balsamifera L.)
Author(s) -
SOOLANAYAKANAHALLY RAJU Y.,
GUY ROBERT D.,
SILIM SALIM N.,
DREWES ERIC C.,
SCHROEDER WILLIAM R.
Publication year - 2009
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.1365-3040.2009.02042.x
Subject(s) - latitude , stomatal conductance , balsam , biology , growing season , photosynthesis , deciduous , salicaceae , photosynthetic capacity , water use efficiency , horticulture , temperate climate , botany , agronomy , woody plant , geography , geodesy
In outdoor common gardens, high latitude populations of deciduous tree species often display higher assimilation rates ( A ) than low latitude populations, but they accomplish less height. To test whether trends in A reflect adaptation to growing season length or, alternatively, are garden growth artefacts, we examined variation in height increment and ecophysiological traits in a range‐wide collection of Populus balsamifera L. populations from 21 provenances, during unconstrained growth in a greenhouse. Rooted cuttings, maintained without resource limitation under 21 h photoperiod for 90 d, displayed increasing height growth, A , leaf mass per area and leaf N per area with latitude whereas stomatal conductance ( g s ) showed no pattern. Water‐use efficiency as indicated by both gas exchange and δ 13 C increased with latitude, whereas photosynthetic nitrogen‐use efficiency decreased. Differences in δ 13 C were less than expected based on A/g s , suggesting coextensive variation in internal conductance ( g m ). Analysis of A – C i curves on a subset of populations showed that high latitude genotypes had greater g m than low‐latitude genotypes. We conclude that higher peak rates of height growth in high latitude genotypes of balsam poplar are supported by higher A , achieved partly through higher g m , to help compensate for a shorter growing season.