Biometrical parameters, pigment content and functional characteristics of photosynthetic apparatus of Bistorta vivipara within the territory of West Spitsbergen

In the present paper, the results of the research of biometric and functional parameters of photosynthetic apparatus of Bistorta vivipara from West Spitsbergen are presented and discussed. A high intraspecific variability of biometric parameters (linear dimensions and biomass) was found. The differences found in biomass suggest that biological productivity is associated with the functional activity of the plant individuals. A direct dependence of the biomass on the photosynthetic pigment content per unit dry mass of leaf has been revealed. A high variability of non-photochemical fluorescence quenching (NPQ), basic fluorescence yield (F), maximal fluorescence yield (F) and variable fluorescence yield (FV) have been shown contrastingly to relatively constant values of the maximum photochemical quantum yield of PS II (F/F) and the coefficient of photochemical fluorescence quenching (qP). Close-to-theoretical-maximum F/F values indicated the absence of stress conditions and the presence of regulation systems in chloroplastic photosynthetic apparatus (PA) level functioning during varying microclimate parameters of the daily climate. The relatively constant qP indicated the same photosynthetic activity of the B. vivipara leaves, unaffected by the varying weather conditions. The NPQ data suggest that the non-photochemical quenching acts as a protective mechanism, sustaining the PA in an optimally active state and reducing probability of negative changes to PSII. The revealed high PA adaptability at the level of the plant structure and light-dependent reactions of photosynthesis makes it possible for B. vivipara to develop at a high functional level at various values of environmental factors, which provides for the successful growth of the species in the high Arctic region. The high PA flexibility suggests that B. vivipara is capable of active adaptation in the context of the forecast climate change.