Effects of thallus temperature and hydration on photosynthetic parameters of Cetraria islandica from contrasting habitats.
|Year of publication||2001|
|Type||Article in Periodical|
|Magazine / Source||Photosynthetica|
|MU Faculty or unit|
|Keywords||lichen photosynthesis chlorophyll fluorescence|
|Description||Two methods of induced in vivo chlorophyll fluorescence were used to investigate the effects of varying thallus temperature and hydration on the performance of photosynthetic apparatus of a foliar lichen Cetraria islandica: slow chlorophyll fluorescence induction kinetic with the analysis of quenching mechanisms, and rapid light response curves of photosynthesis derived from quantum yield of photochemical reactions of photosystem II (FII) recorded at increasing light intensities. The paper compares responses of photosynthetic apparatus in populations of C. islandica growing in lower altitude (LAP: 1350 m a.s.l.) and in higher altitude (HAP: 2000 m a.s.l.). At each altitude, the samples were collected both in fully irradiated sites (HL) and in shade (LL). Temperature optimum of photosynthetic processes was the same for LAP and HAP thalli of LL populations (18 oC), while it was significatly lower for HL HAP (14 oC). Gradual dehydration of fully hydrated thalli led to initial increase (up to 20 % of water saturation deficit - WSD) in FV/FM and FII, no change at 20-50 % WSD, and a dramatic decrease of the parameters within 50-80 % of WSD. It was concluded that LL HAP of C. islandica was the best adapted population to low temperature having higher rates of photochemical processes of photosynthesis than HL HAP within temperature range of -5 to +5 oC. The differences between populations were apparent also in chlorophyll content and thallus morphology.|