1. Nutrient supply has greater influence than sink strength on photosynthetic adaptation to CO2 elevation in white birch seedlings.
- Author
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Zhang S, Dang QL, and Cao B
- Subjects
- Betula drug effects, Betula metabolism, Biomass, Carbon Dioxide metabolism, Chlorophyll metabolism, Electron Transport, Nitrogen analysis, Oxygen metabolism, Photosynthesis, Photosystem II Protein Complex, Plant Leaves drug effects, Plant Leaves metabolism, Plant Leaves physiology, Plant Roots drug effects, Plant Roots metabolism, Plant Roots physiology, Plant Transpiration, Seedlings drug effects, Seedlings metabolism, Adaptation, Physiological, Betula physiology, Carbon Dioxide pharmacology, Nitrogen metabolism, Seedlings physiology
- Abstract
To study the effects of source-sink ratio and nutrient supply on photosynthetic acclimation to CO(2) elevation, we subjected white birch seedlings to two levels of nutrient supply (high vs. low) and CO(2) concentrations (ambient vs. doubled [CO(2)]) for two months and then shaded the lower canopy on half of the seedlings to reduce source/sink ratio for an additional month. The CO(2) elevation significantly increased P(n) and IWUE at both nutrient levels but the increase was greater in the high than low nutrient treatment. The CO(2) elevation resulted in a down-regulation of V(cmax) in the low nutrient treatment but up-regulation of J(max), TPU, [Formula: see text] and J(c) in the high nutrient after 3 months of treatment. Both the CO(2) elevation and high nutrient supply increased the partition of total electron transport to carboxylation at the expense of oxidation. The seedlings responded to the shading of the lower canopy by reducing biomass allocation to roots rather than making physiological adjustments to unshaded leaves in the upper canopy. Our results suggest that the direction of photosynthetic acclimation to CO(2) elevation in white birch was nutrient-dependent and an increase in sink strength could reduce the feedback inhibition of photosynthesis., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2013
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