Abstract
High temperature stress imposes constraints on the productivity of agricultural systems, such as pastures, and predicted increases in global temperatures are set to exacerbate these limitations. Here, we sought to understand the impact of warmer growth temperature on gas exchange and net primary productivity for two widely cultivated pasture species. We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT). Soil water was maintained at non-limiting conditions in both temperature treatments to control for the confounding effects of warming on soil moisture. We found that warming reduced photosynthetic capacity and increased leaf dark respiration (Rdark) in lucerne, while tall fescue showed little physiological change at the leaf level, but increased ecosystem respiration (Reco). Growth temperature had no significant impact on the thermal optimum of photosynthesis (Topt) or water use efficiency in either species. Both species exhibited significant reductions in productivity with warming; lucerne had greater reductions in shoot biomass, while tall fescue had greater reductions in root biomass. Our results highlight the potential for significant declines in pasture productivity associated with even modest increases in average temperature and highlights the need for suitable management strategies and implementation of more heat-resistant cultivars. Improvements in photosynthetic performance for greater heat tolerance in lucerne, and traits associated with biomass allocation and root performance at higher temperatures in tall fescue, should be the focus for improving high temperature resistance in these plant species.
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Claims 13
Claim · model-written summary
Warming reduced photosynthetic capacity in lucerne.
- Taxon
- Medicago sativa
Medicago sativae0 - Treatment
- warminge1
- Outcome
- photosynthetic capacitye1
- Direction
- reducede1
- Comparator
- ambiente0
- Setting
- climate-controlled facilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e1“warming reduced photosynthetic capacity and increased leaf dark respiration (Rdark) in lucerne”
Claim · model-written summary
Warming increased leaf dark respiration in lucerne.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- warminge1
- Outcome
- leaf dark respiratione1
- Direction
- increasede1
- Comparator
- ambiente0
- Setting
- climate-controlled facilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e1“warming reduced photosynthetic capacity and increased leaf dark respiration (Rdark) in lucerne”
Claim · model-written summary
Tall fescue showed little change in leaf-level physiology under warming.
- Taxon
- Festuca arundinacea
Lolium arundinaceume0 - Treatment
- warminge1
- Outcome
- physiological change at the leaf levele2
- Direction
- no_changeinferrede2
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e1“warming reduced photosynthetic capacity and increased leaf dark respiration (Rdark) in lucerne”
e2“while tall fescue showed little physiological change at the leaf level, but increased ecosystem respiration (Reco)”
Claim · model-written summary
Warming increased ecosystem respiration in tall fescue.
- Taxon
- Festuca arundinaceaLolium arundinaceume0
- Treatment
- warminge1
- Outcome
- ecosystem respiration (Reco)e2
- Direction
- increasede2
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e1“warming reduced photosynthetic capacity and increased leaf dark respiration (Rdark) in lucerne”
e2“while tall fescue showed little physiological change at the leaf level, but increased ecosystem respiration (Reco)”
Claim · model-written summary
Growth temperature had no significant effect on the thermal optimum of photosynthesis or water use efficiency in lucerne.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- Growth temperaturee3
- Outcome
- the thermal optimum of photosynthesis (Topt) or water use efficiencye3
- Direction
- no_changeinferrede3
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e3“Growth temperature had no significant impact on the thermal optimum of photosynthesis (Topt) or water use efficiency in either species”
Claim · model-written summary
Growth temperature had no significant effect on the thermal optimum of photosynthesis or water use efficiency in tall fescue.
- Taxon
- Festuca arundinaceaLolium arundinaceume0
- Treatment
- Growth temperaturee3
- Outcome
- the thermal optimum of photosynthesis (Topt) or water use efficiencye3
- Direction
- no_changeinferrede3
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e3“Growth temperature had no significant impact on the thermal optimum of photosynthesis (Topt) or water use efficiency in either species”
Claim · model-written summary
Warming significantly reduced productivity in lucerne.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- warminge5
- Outcome
- productivitye5
- Direction
- reductionse5
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e5“Both species exhibited significant reductions in productivity with warming”
Claim · model-written summary
Warming significantly reduced productivity in tall fescue.
- Taxon
- Festuca arundinaceaLolium arundinaceume0
- Treatment
- warminge5
- Outcome
- productivitye5
- Direction
- reductionse5
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e5“Both species exhibited significant reductions in productivity with warming”
Claim · model-written summary
Lucerne had greater reductions in shoot biomass than tall fescue under warming.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- warminge5
- Outcome
- shoot biomasse4
- Direction
- greater reductionse4
- Comparator
- tall fescuee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e4“lucerne had greater reductions in shoot biomass, while tall fescue had greater reductions in root biomass”
e5“Both species exhibited significant reductions in productivity with warming”
Claim · model-written summary
Tall fescue had greater reductions in root biomass than lucerne under warming.
- Taxon
- Festuca arundinaceaLolium arundinaceume0
- Treatment
- warminge5
- Outcome
- root biomasse4
- Direction
- greater reductionse4
- Comparator
- lucernee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew a C3 legume, Medicago sativa (lucerne), and a C3 grass, Festuca arundinacea Schreb. (tall fescue), in a climate-controlled facility exposed to two temperature treatments (ambient: 26 °C, aT; elevated: 30 °C, eT)”
e4“lucerne had greater reductions in shoot biomass, while tall fescue had greater reductions in root biomass”
e5“Both species exhibited significant reductions in productivity with warming”
Claim · model-written summary
Suitable management strategies and more heat-resistant cultivars are needed for these pasture species.
- Taxon
- Medicago sativa L.Medicago sativat0
- Outcome
- implementation of more heat-resistant cultivarse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Warming Reduces Net Carbon Gain and Productivity in Medicago sativa L. and Festuca arundinacea”
e6“the need for suitable management strategies and implementation of more heat-resistant cultivars”
Claim · model-written summary
Improving photosynthetic performance for greater heat tolerance should be the focus in lucerne.
- Taxon
- lucerneMedicago sativae7
- Outcome
- photosynthetic performance for greater heat tolerancee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Improvements in photosynthetic performance for greater heat tolerance in lucerne”
Claim · model-written summary
Biomass allocation and root performance at higher temperatures should be the focus in tall fescue.
- Taxon
- tall fescueLolium arundinaceume1
- Outcome
- traits associated with biomass allocation and root performance at higher temperaturese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“traits associated with biomass allocation and root performance at higher temperatures in tall fescue”
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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.