CALLOSE CONCENTRATION IN LEAVES OF FIELD-GROWN OXALIS-ACETOSELLA (L) INDICATES GROWTH IMPEDIMENTS

The Hoglwald, located in Bavaria, is a pure Norway spruce stand, where experimental plots which were limed or not were subjected to normal o r acid irrigation (Hoglwald Experiment). The growth of the forest herb Oxalis acetosella improved greatly with liming. Callose concentration in leaves of Oxalis reflected the lime effect with about a 2.5 times lower callose concentration in the limed compared to unlimed plots. Ac id irrigation increased callose concentration only in the unlimed plot . A negative exponential relationship was established between leaflet area and callose concentration. In a Diagnostic Field Fertilization Ex periment in the vicinity of the Hoglwald Experiment, Ca and Mg were ap plied either as carbonate or sulphate and Mn and Si added to experimen tal plots. In this experiment, it was demonstrated that it was not lim ing per se, but the application of Ca, that greatly increased the grow th of Oxalis. Again, there was a negative correlation between leaflet area and callose concentration in leaves. Chemical analysis of leaves revealed that a Mn concentration > 3.5 mg (g DW)-1 and a Mg concentrat ion > 10 mg (g DW)-1 led to increased callose concentration.