Abstract
Abstract Plant responses to carbon (C) and water availability are strongly connected. Thus, we can learn much about the responses of modern plants to rising atmospheric carbon dioxide (CO 2 ) by studying their performance under a range of carbon and water availabilities, including very low CO 2 as in past glacial periods. We hypothesized that, especially in shallow soils, the positive effects of high CO 2 and the negative effects of low CO 2 on growth response to drought are moderated by plant size‐driven feedbacks through transpiration and soil water depletion. We grew two temperate annual C 3 species, Avena sativa and Chenopodium album, in glacial (180 ppm), modern (400 ppm) and future (700 ppm) CO 2 levels and five soil water regimes in climate chambers. In both species, low CO 2 resulted in a much lower relative growth rate, biomass and total leaf area than at ambient CO 2 with higher water availability, but this difference disappeared steadily towards severe drought conditions. Elevated CO 2 increased relative growth rate, plant biomass and total leaf area of both species slightly compared with ambient CO 2 . These results were especially pronounced under drought. Our results support the hypothesis that, in annuals, plant size modulates the negative drought effect at low CO 2 . However, plant size‐mediated effects of high CO 2 on growth response to drought were inconclusive. Further experiments should reveal the interactive effects of CO 2 and water regimes in environments closer to a field setting, both in shallow and in deep soils with unconstrained rooting, as well as in mixed communities.
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Claims 4
Claim · model-written summary
Low CO2 lowered relative growth rate, biomass and leaf area in both species under greater water availability, with the difference fading under severe drought.
- Taxon
- Avena sativa and Chenopodium album
Chenopodium album
Avena sativae0 - Treatment
- low CO 2e1
- Outcome
- relative growth rate, biomass and total leaf areae1
- Direction
- much lowere1
- Qualifier
- higher water availabilitye1
- Comparator
- ambient CO 2e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Avena sativa and Chenopodium album”
e1“low CO 2 resulted in a much lower relative growth rate, biomass and total leaf area than at ambient CO 2 with higher water availability, but this difference disappeared steadily towards severe drought conditions”
Claim · model-written summary
Elevated CO2 slightly increased relative growth rate, biomass and leaf area, especially during drought.
- Taxon
- Avena sativa and Chenopodium albumChenopodium albumAvena sativae0
- Treatment
- Elevated CO 2e1
- Outcome
- relative growth rate, plant biomass and total leaf areae1
- Direction
- increasede1
- Qualifier
- under droughte1
- Comparator
- ambient CO 2e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Avena sativa and Chenopodium album”
e1“Elevated CO 2 increased relative growth rate, plant biomass and total leaf area of both species slightly compared with ambient CO 2 . These results were especially pronounced under drought”
Claim · model-written summary
Plant size modulated the negative drought effect at low CO2.
- Taxon
- Avena sativa and Chenopodium albumChenopodium albumAvena sativae0
- Outcome
- negative drought effecte1
- Qualifier
- plant sizee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Avena sativa and Chenopodium album”
e1“plant size modulates the negative drought effect at low CO 2”
Claim · model-written summary
Plant size effects at high CO2 were inconclusive.
- Taxon
- Avena sativa and Chenopodium albumChenopodium albumAvena sativae0
- Outcome
- growth response to droughte1
- Qualifier
- inconclusivee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Avena sativa and Chenopodium album”
e1“plant size‐mediated effects of high CO 2 on growth response to drought were inconclusive”
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See all 7 papers →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.