title: Simulating the germination response to diurnally alternating temperatures under climate change scenarios: comparative studies on Carex diandra seeds.
abstract: OBJECTIVE
  Environmental temperature regulates plant regeneration via seed in several superimposed ways, and this complex regulation will be disrupted by climate change. The role of diurnally alternating temperatures (ΔT) in terminating dormancy will be a major factor in this disruption, as its effects on seed germination are immediate.
  
  
  METHODS
  The effect of ΔT on seed germination was modelled using two populations of the wetland sedge Carex diandra, one from a montane site and one from a subalpine site. A cardinal-temperature model was fitted to germination results obtained from a thermal gradient plate, and the model was used to simulate changes in germination under two possible future climate scenarios (RCP2·6 and RCP8·5, for representative concentration pathways) as defined by the Intergovernmental Panel on Climate Change.
  
  
  RESULTS
  Scenario RCP2·6 projected moderate increases in average temperatures and ΔT, whereas RCP8·5 projected greater warming and higher ΔT. Increasing ΔT decreased the base temperature for seed germination and the thermal time required for germination. The effect of higher ΔT together with the higher temperatures increased germination under both climate scenarios.
  
  
  CONCLUSIONS
  Carex diandra germination is highly responsive to potential changes in ΔT, and thus this study highlights the role of ΔT in seed responses to climate change. Comprehensive cardinal-temperature models, encompassing the different effects of temperature on seed germination, are needed to understand how climate change will affect plant regeneration.
authors.affiliation: Jardín Botánico Atlántico, Universidad de Oviedo, Avda. del Jardín Botánico 2230, 33394 Gijón/Xixón, Spain and Seed Conservation Department, Royal Botanic Gardens, Kew, Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Fernández-Pascual
authors.affiliation: Jardín Botánico Atlántico, Universidad de Oviedo, Avda. del Jardín Botánico 2230, 33394 Gijón/Xixón, Spain and Seed Conservation Department, Royal Botanic Gardens, Kew, Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK c.seal@kew.org.
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Seal
authors.affiliation: Jardín Botánico Atlántico, Universidad de Oviedo, Avda. del Jardín Botánico 2230, 33394 Gijón/Xixón, Spain and Seed Conservation Department, Royal Botanic Gardens, Kew, Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK.
authors.forename: Hugh W
authors.initials: HW
authors.lastname: Pritchard
mesh_terms: D031255:Carex Plant / Q000502:physiology*; D002940:Circadian Rhythm; D057231:Climate Change; D018525:Germination; D006358:Hot Temperature; D058614:Seed Dispersal; D012639:Seeds / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
keywords: Cardinal-temperature models; climate change; germination thermal threshold models; physiological dormancy; plant regeneration; plant–climate interactions; representative concentration pathways; seed ecology