Ambient UV‐B radiation decreases photosynthesis in high arctic Vaccinium uliginosum

Abstract

An UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis but also the effects on other parts of the photosynthetic machinery, e.g. the Calvin cycle, might be important. The 60% reduction of the UV-B irradiance used in this study implies a higher relative change in the UV-B load than many of the supplemental experiments do, but the substantial effect on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B.

Current and future impacts of ultraviolet radiation on the terrestrial carbon balance

“…These effects include a reduction in the capture of carbon via decreased photosynthetic carbon gain, as well as an increase in carbon release via accelerated litter decomposition. To date, photosynthesis has been shown to be inhibited by UV radiation through the sensitivity of photosynthetic machinery (Albert et al, 2008) and by the alteration of gene expression, which is critical to photosynthesis (Ballare et al, 1996;Casati and Walbot, 2004;Izaguirre et al, 2003;Savenstrand et al, 2002).…”

Effect of Exclusion of Solar UV radiation on Plants

“…Bredahl et al (2004, p.363) reported higher maximal photochemical efficiency (measured as the chlorophyll fluorescence parameter Fv/Fm) under UV-B reduction. Quantum efficiencies, specific and phenomenological fluxes were all enhanced by UV exclusion indicating a negative impact of ambient UV on all of these parameters in the plant species (Albert, Mikkelsen, & Ro-Poulsen, 2005, Albert, Mikkelsen, & Ro-Poulsen, 2008, Albert et al, 2010, p.1542Kataria et al, 2013, p.140). The increases in the efficiency that an absorbed photon will be trapped by the PSII reaction centre with the resultant reduction of QA to QA -(ET0/ABS = FV/FM) and the efficiency that an electron residing on QA-will enter the intersystem electron transport chain (ET0/TR0) were observed in reduced UV-B.…”

“…The UV-exclusion experiments showed that a reduction of the ambient UV-B level resulted in decreased content of UV-B absorbing compounds and lower stress level indicated by increased maximal quantum yield (FV/FM) and Performance Indexes (PI) (Bredahl, Ro-Poulsen, Mikkelsen, 2004;Albert et al, 2005Albert et al, , 2008Albert et al, , 2010Kataria et al, 2013, p.140). Bredahl et al (2004, p.363) reported higher maximal photochemical efficiency (measured as the chlorophyll fluorescence parameter Fv/Fm) under UV-B reduction.…”

An Overview of Plant Photosynthesis Modulation by Pathogen Attacks

“…Nontheless, many temperate plant species may not adapt as rate of photosynthesis was found to decline at moderately high temperature in a temperate species such as Arabidopsis thaliana (Kumar et al, 2009, Kurek et al, 2007. If CO 2 generally favours photosynthesis, other environmental clues such as UV-B (Albert et al, 2008), heat shock and water deficit (Abrams et al, 1990, Ackerson and Hebert, 1981, Allakhverdiev et al, 2008, ZhangWollenweber et al, 2008), Cold (Batista-Santos et al, 2011, Bilska and Sowinski, 2010, herbivore and pathogen attacks have detrimental effects on photosynthesis (Halitschke et al, 2011, Horst et al, 2008, King and Caylor, 2010, Nabity et al, 2009). The primary targets of thermal damage in plants are the oxygen evolving complex along with the associated cofactors in photosystem II (PSII), carbon fixation by Rubisco and the ATP generating system (Allakhverdiev et al, 2008).…”