Figure 1

Effects of R -(-)- (continuous line) and S -(+)-carvone (dotted line) on relative activity (mean ± standard error). (a) dehydrogenase, (b) urease, (c) alkaline phospho-monoesterase and (d) relative soil respiration, during the incubation period lasting four weeks. Carvones were added at times 0 and 2. Letters correspond to significant differences due to the combined effect of treatment (compound) with time for enzymatic activities and to the treatment effect for soil respiration; asterisks denote significant differences between treatments and corresponding controls, at each sampling point, separately (χ² test) (ns = non significant differences, * = p < 0.05, ** =p < 0.01, *** = p < 0.001).