TITLE:
Soil Temperature and Phosphorus Supply Interactively Affect Physiological Responses of White Birch to CO2 Elevation
AUTHORS:
Gabriel Danyagri, Qing-Lai Dang
KEYWORDS:
Betula papyrifera Mash; Foliar Gas Exchange; Water-Use-Efficiency; Stomatal Conductance; Rubisco; Boreal Trees; Climate Change
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.2,
January
24,
2014
ABSTRACT: Phosphorus (P) is a common limiting nutrient
element to plants and its supply and uptake by plants are strongly influenced
by soil temperature. However, the interactive effects of the two factors on the
physiological responses of plants to global change are poorly understood. In
this study, we examined how P supply and Tsoil interacted in
affecting physiological responses in white birch (Betula papyrifera) to [CO2]. We exposed seedlings to 7°C,
17°C and 27°C Tsoil, 0.1479, 0.3029 and 0.5847 mM P2O5,
and 360 and 720 μmol·mol-1 [CO2] for four months. We have
found that both the low soil temperature and CO2 elevation resulted
in photosynthetic down regulation but the specific mechanisms of the down
regulation were different between the two treatments, particularly the relative
contributions of biochemical and photochemical capacity, mesophyll conductance
and sink strength for carbohydrate utilization to the down regulation.
Furthermore, our data suggest that morphological adjustments, such as reduced
leaf size and total leaf area, were the primary form of responses in white
birch to low phosphorus supply and no significant physiological acclimation to
P supply was detected. Our results suggest that white birch will likely enhance
water use efficiency under the projected future climate conditions with doubled
carbon dioxide concentration, particularly at warmer soil temperatures. Although
a trade-off between water use efficiency and nutrient use efficiency is widely
accepted, our results suggest that there does not have to be a trade-off
between the two, for instance, CO2 elevation increased both use
efficiencies and low soil temperature and reduced
nitrogen efficiency without affecting water use efficiency under elevated CO2.