Responses of primary photosynthetic processes to repetitive rehydration differ in two representatives of Svalbard moss flora

Global warming in polar regions brings a risk of more frequent and long-lasting dry periods due to warmer windier climate during summers. Mosses are well adapted desiccation-rehydration events they have evolved remarkable constitutive inducible mechanisms desiccation tolerance. In our study, Sanionia uncinata Racomitrium lanuginosum were collected Svalbard used for laboratory-based repetitive 32-h-lasting rehydration cycles with continuous monitoring restoration their primary photosynthetic processes measured by chlorophyll fluorescence parameters. Immediately after the addition water thalli, potential quantum yield PSII (FV/FM) was about 50% its maximum reached 32 h rehydration. course time rehydration, both species showed an increase FV/FM effective (FPSII) following S-curve relationship. Non-photochemical quenching did not show clear trend time, It differed between two decrease Relative (RFd), which is considered vitality indicator, showing similar trends first third cycle The results indicate that resistant since FPSII recovered fully there we only minor differences parameters cycle.