Green, TGA/ Lange, OL/ Cowan, IR 1994: Ecophysiology of lichen photosynthesis: the role of water status and thallus diffusion resistances. - Cryptogamic Botany4: 166-178. [RLL List # 157 / Rec.# 7008] Keywords: CO2 COMPENSATION/ CO2 CONCENTRATING MECHANISM/ CO2 DIFFUSION/ ECOPHYSIOLOGY/ PHOTOSYNTHESIS/ WATER BALANCE/ WATER CONTENT
Abstract: 12 fig. 2 tab. ["Lichens are poikilohydric plants and, as such, their thallus water content (WC) tends to equilibrate with the atmospheric humidity. An analysis is made of the typical response of lichen photosynthesis to thallus WC which is a three (subjectively delimitated) phase curve. At low WC the metabolism is thought to be limited by the low water potential and net photosynthesis (PN) is almost linearly related to WC. Green algal lichens show the special ability to achieve positive PN by equilibration only with atmospheric humidity. Factors that limit maximal PN at optimal WC have yet to be satisfactorily described. At high WC many lichens show a depression in PN and the evidence is summarised to show that this is a result of increased thallus CO2 diffusion resistances."]