SNA and Metal Transport in Terrestrial Plants

There are various concentration and other chemical gradients inside a plant, and there is stimulation of gradient formation and some uneven distribution (see Sterner and Elser 2(X)2 for the various parts of an apple tree or the autoradiographs on certain elements in different plant species (Figs. 2.7 and 2.8)) will cause trapping of some elements somewhere in the plant, e.g. transport may be stopped at the root/xylem (shoot) 

The ratios among C, N and P in an organism are the classical parameters of ecological stoichiometry (Sterner and Elser 2002). These three non-metals are all involved in binding metal ions to biomass  

Now we are to determine which of these four non-metals prevails in metal biocomplexation, taking into account the 

2 Autocatalytic Processes and the Role of Essential Elements in Plant Growth 

C/N in higher plants is 7-30 for the entire plant but 20-50 for photosynthetic organs, N/P uses to be 50-80 and C/S about 500 (stoichiometric ratios each). Both S and Se are partly bound into ligands (cysteine, methionine, selenocysteine, dimethyl selenide and many plant components such as those of Allium species including garlic), but likewise partly in weakly complexing anions like SO/ or SeO , respectively (total S in leaves or needles is about 3 mg/g DM or 90 mmol/kg C/S 450 and N/S 20). 

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