Fv/Fm acclimation to the Mediterranean summer drought in two sympatric Lasallia species from the Iberian mountains

Abstract

AbstractPhotosynthetic performance in lichens can vary throughout the year. We investigate the variation in the PSII quantum efficiency as a proxy for the physiological state of the photosynthetic apparatus in two umbilicate species from the genus Lasallia. Temporal variation in Fv/Fm in both species was monitored at a field site in Central Spain where both species coexist. Subsequent measurements were carried out in the laboratory after 48 h preconditioning. Both species showed clear variation during the year in PSII performance, with a marked depression in Fv/Fm during the summer. Lasallia pustulata consistently had higher Fv/Fm values than L. hispanica. Both species reached higher Fv/Fm values after 48 h of preconditioning in the laboratory and this recovery was particularly notable in the summer months. Fv/Fm was highly related to antecedent weather conditions during the two days prior to measurement.