Evaluating Leaf Ash Content and Potassium Concentration as Surrogates of Carbon Isotope Discrimination in Grassland Species |
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| Authors: | J T Tsialtas M Kassioumi & D S Veresoglou |
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| Institution: | Aristotle University of Thessaloniki, School of Agriculture, Laboratory of Ecology &Environmental Protection (267), 540 06 Thessaloniki, Greece |
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| Abstract: | Leaf ash content and potassium (K) concentration were evaluated as surrogates of carbon isotope discrimination (Δ) of the dominant species in an upland grassland in a 3-year experiment. Previous results reported positive correlations between Δ and ash content or mineral concentrations, attributing this relationship to the passive accumulation, through the transpiration stream, of minerals in the vegetative plant parts. We found only a weak positive correlation between Δ and ash content or K concentration in 1997 (r=0.79, P < 0.05 and r=0.77, P < 0.05, respectively). No significant correlation was found between the traits in 1998 and 1999. When four of the seven most abundant species ( Poa pratensis , Lolium perenne , Festuca valida and Taraxacum officinale ) were grown under different treatments (mixed sward, monoculture, and nitrogen and P additions in mixed sward), a curvilinear relationship between Δ and ash content or K concentration was evident. Thus, our findings suggest that leaf ash content and K concentration cannot serve as surrogates of carbon isotope discrimination (Δ). Small genotype × environment interactions were reported for the three traits measured; the interactions were smallest for ash content. A positive correlation between leaf ash content and soil water content (at 5 and 15 cm depth) was found for four species ( P. pratensis , L. perenne , F. valida and Achillea millefolium ) and for the community as a whole. No significant correlation was found between leaf K concentration and soil water content. |
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| Keywords: | ash content carbon isotope discrimination grassland species potassium |
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