Analysis of variance for prunasin concentration in roots of Prunus serotina seedlings acclimated to one of three light regimes: 10 % low light (LL), 25 % medium light (ML), or 100 % high light (HL) of full natural sun light. Samples were taken on three occasions: in June (DOY 176, DOY – day of year), in August (DOY 238), and in September (DOY 273). The split-split plot model of ANOVA was applied with block, time of sampling, light treatment, combination, and interactions as the sources of variance. The differences were significant at P ≤ 0.05. MS – mean sum of squares, F – value of Snedecor’s function, in bold – statistically significant at P < 0.05 (N = 106, N – number of seedlings)