title: Diffusional limitations explain the lower photosynthetic capacity of ferns as compared with angiosperms in a common garden study.
abstract: Ferns are thought to have lower photosynthetic rates than angiosperms and they lack fine stomatal regulation. However, no study has directly compared photosynthesis in plants of both groups grown under optimal conditions in a common environment. We present a common garden comparison of seven angiosperms and seven ferns paired by habitat preference, with the aims of (1) confirming that ferns do have lower photosynthesis capacity than angiosperms and quantifying these differences; (2) determining the importance of diffusional versus biochemical limitations; and (3) analysing the potential implication of leaf anatomical traits in setting the photosynthesis capacity in both groups. On average, the photosynthetic rate of ferns was about half that of angiosperms, and they exhibited lower stomatal and mesophyll conductance to CO2 (gm ), maximum velocity of carboxylation and electron transport rate. A quantitative limitation analysis revealed that stomatal and mesophyll conductances were co-responsible for the lower photosynthesis of ferns as compared with angiosperms. However, gm alone was the most constraining factor for photosynthesis in ferns. Consistently, leaf anatomy showed important differences between angiosperms and ferns, especially in cell wall thickness and the surface of chloroplasts exposed to intercellular air spaces.
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca Illes Balears, 07122, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Carriquí
authors.forename: H M
authors.initials: HM
authors.lastname: Cabrera
authors.forename: M À
authors.initials: MÀ
authors.lastname: Conesa
authors.forename: R E
authors.initials: RE
authors.lastname: Coopman
authors.forename: C
authors.initials: C
authors.lastname: Douthe
authors.forename: J
authors.initials: J
authors.lastname: Gago
authors.forename: A
authors.initials: A
authors.lastname: Gallé
authors.forename: J
authors.initials: J
authors.lastname: Galmés
authors.forename: M
authors.initials: M
authors.lastname: Ribas-Carbo
authors.forename: M
authors.initials: M
authors.lastname: Tomás
authors.forename: J
authors.initials: J
authors.lastname: Flexas
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D004058:Diffusion; D004579:Electron Transport; D029624:Ferns / Q000033:anatomy & histology / Q000502:physiology*; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000502:physiology*; D058503:Mesophyll Cells / Q000473:pathology; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology; D054046:Plant Stomata / Q000033:anatomy & histology / Q000502:physiology; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D002245:Carbon Dioxide
keywords: leaf anatomy; photosynthesis; pteridophytes