Comparative photosynthetic capacity, respiration rates, and nutrient content of micropropagated and wild-sourcedSphagnum

Abstract

AbstractRapid, effective restoration of degraded peatlands is urgently needed to reduce their current high levels of carbon loss. Re-introduction ofSphagnummoss, along with re-wetting, is key to returning carbon sequestration and retention capabilities to northern degraded bogs. Micropropagated (BeadaMoss®)Sphagnumhas already been applied in large quantities, and more is planned, for restoration projects in Britain and parts of Europe. Comparison with wild-sourcedSphagnummaterial is therefore pertinent to demonstrate its safety and suitability for wide-scale application. SixSphagnumspecies of micropropagated and wild-sourced origin were studied:S. capillifolium,S. fallax,S. palustre,S. papillosum,S. medium/divinumandS. squarrosum. MicropropagatedSphagnumhad significantly higher light-saturated photosynthesis (Pmax) rates, little colour expression, an open habit (shoots separated), higher numbers of chloroplasts, and more numerous, smaller shoot apices (capitula) than wild-sourcedSphagnum. Potentially, greater numbers of chloroplasts in micropropagatedSphagnumfacilitate higher photosynthesis rates, driving rapid growth in early-stage plants, particularly in optimum moisture conditions. Pmax rates were associated with lower bulk density (mass/volume) and higher nutrient concentrations in tissues. MicropropagatedSphagnum, grown with additional nutrients, showed no sign of nutrient toxicity or limited P or K, despite a N content approaching 30 mg g-1(well above the highest literature-reported concentration threshold), indicating its nutrient-demanding early growth stage. Ranking species according to their Pmax and respiration rates (expressed on a dry matter basis) found thatS. squarrosumwas the highest andS. medium/divinumwas the lowest, in both micropropagated and wild-sourcedSphagnum. MicropropagatedSphagnumis similar in form to wild-sourced, can be propagated in large quantities, and due to high photosynthesis rates and absorption of nutrients, is likely to establish well on application to a site where re-wetting has already occurred, therefore making it highly beneficial for restoration of degraded bogs.