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Genetic variation of ecophysiological traits in red alder (Alnus rubra Bong.)

Dang, Q.L., Xie, C.Y., Ying, C., Guy, R.D.
Canadian journal of forest research = 1994 v.24 no.11 pp. 2150-2156
Alnus rubra, provenance, genetic variation, photosynthesis, leaf conductance, stomata, xylem water potential, mesophyll, drought tolerance, adaptation, water vapor, British Columbia
We examined the genetic variation of ecophysiological traits within and among 40 red alder (Alnus rubra Bong.) provenances (two families per provenance) in a common-garden experiment in the summer of 1993. The provenances were representative of the entire species range in British Columbia, Canada. We found significant genetic variation among provenances (P < 0.001) in photosynthetic rate (A), mesophyll conductance (g(m)), transpiration rate (E), stomatal conductance (g(sw)), stomatal sensitivity to water vapour pressure deficit (SENS(VPD)), intercellular to ambient CO2 concentration ratio (Ci/Ca), and midday xylem water potential. Photosynthetic water-use efficiency, however, did not differ significantly among provenances. There were no significant differences between families within provenance for any of these variables. A weak but significant geographic trend was detected in ecophysiological traits: midday xylem water potential, A, g(m), and E increased, and SENS(VPD) decreased, from southeast to northwest. Photosynthetic rate, E, g(m), g(sw) and midday xylem water potential were positively related to each other, but negatively correlated with SENS(VPD). Ci/Ca was negatively correlated with g(sw). These correlations indicate that red alder might have undergone genetic differentiation in drought resistance.