Abstract
Predictions of shifts in rainfall patterns as atmospheric [CO2] increases could impact the growth of fast growing trees such as Populus spp. and Salix spp. and the interaction between elevated CO2 and water stress in these species is unknown. The objectives of this study were to characterize the responses to elevated CO2 and water stress in these two species, and to determine if elevated CO2 mitigated drought stress effects. Gas exchange, water potential components, whole plant transpiration and growth response to soil drying and recovery were assessed in hybrid poplar (clone 53-246) and willow (Salix sagitta) rooted cuttings growing in either ambient (350 &mgr;mol mol-1) or elevated (700 &mgr;mol mol-1) atmospheric CO2 concentration ([CO2]). Predawn water potential decreased with increasing water stress while midday water potentials remained unchanged (isohydric response). Turgor potentials at both predawn and midday increased in elevated [CO2], indicative of osmotic adjustment. Gas exchange was reduced by water stress while elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species. Dark respiration decreased in elevated [CO2] and water stress reduced Rd in the trees growing in ambient [CO2]. Willow had 56% lower whole plant hydraulic conductivity than poplar, and showed a 14% increase in elevated [CO2] while poplar was unresponsive. The physiological responses exhibited by poplar and willow to elevated [CO2] and water stress, singly, suggest that these species respond like other tree species. The interaction of [CO2] and water stress suggests that elevated [CO2] did mitigate the effects of water stress in willow, but not in poplar.
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Claims 14
Claim · model-written summary
Predawn water potential declined with increasing water stress.
Populus
SalixOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Predawn water potential decreased with increasing water stress while midday water potentials remained unchanged (isohydric response).”
t0“poplar and willow”
Claim · model-written summary
Midday water potential remained unchanged with increasing water stress.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Predawn water potential decreased with increasing water stress while midday water potentials remained unchanged (isohydric response).”
t0“poplar and willow”
Claim · model-written summary
Elevated carbon dioxide increased predawn and midday turgor potentials.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Turgor potentials at both predawn and midday increased in elevated [CO2], indicative of osmotic adjustment.”
t0“poplar and willow”
Claim · model-written summary
Water stress reduced gas exchange.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange was reduced by water stress while elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species.”
t0“poplar and willow”
Claim · model-written summary
Elevated carbon dioxide increased photosynthetic rates.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species.”
t0“poplar and willow”
Claim · model-written summary
Elevated carbon dioxide reduced leaf conductance.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species.”
t0“poplar and willow”
Claim · model-written summary
Elevated carbon dioxide nearly doubled instantaneous transpiration efficiency.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] increased photosynthetic rates, reduced leaf conductance and nearly doubled instantaneous transpiration efficiency in both species.”
t0“poplar and willow”
Claim · model-written summary
Elevated carbon dioxide decreased dark respiration.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Dark respiration decreased in elevated [CO2] and water stress reduced Rd in the trees growing in ambient [CO2].”
t0“poplar and willow”
Claim · model-written summary
Water stress reduced dark respiration in trees at ambient carbon dioxide.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“water stress reduced Rd in the trees growing in ambient [CO2].”
t0“poplar and willow”
Claim · model-written summary
Willow had 56% lower whole plant hydraulic conductivity than poplar.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Willow had 56% lower whole plant hydraulic conductivity than poplar”
Claim · model-written summary
Elevated carbon dioxide increased willow whole plant hydraulic conductivity by 14%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Willow had 56% lower whole plant hydraulic conductivity than poplar, and showed a 14% increase in elevated [CO2] while poplar was unresponsive.”
Claim · model-written summary
Poplar whole plant hydraulic conductivity was unresponsive to elevated carbon dioxide.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Willow had 56% lower whole plant hydraulic conductivity than poplar, and showed a 14% increase in elevated [CO2] while poplar was unresponsive.”
Claim · model-written summary
Elevated carbon dioxide mitigated water stress effects in willow.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] did mitigate the effects of water stress in willow, but not in poplar.”
Claim · model-written summary
Elevated carbon dioxide did not mitigate water stress effects in poplar.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] did mitigate the effects of water stress in willow, but not in poplar.”
The same questions in other papers
co2 · physiology: water · Populus (poplar)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
drought · physiology: gas exchange · Salix (willows)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- negative
co2 · physiology: gas exchange · Populus (poplar)Positive and negative results
3 in the opposite direction
- negative
- no effect
- no effect
co2 · physiology: photosynthesis · Populus (poplar)Positive and negative results
9 papers in the same direction as this paper · 1 in the opposite direction
- positive
- positive
- negative
7 papers more in this group
See all 11 papers →drought · physiology: gas exchange · Populus (poplar)Results agree
2 papers in the same direction as this paper
- negative
- negative
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.