**2.5 Statistical analysis**

Statistical analysis of the data was performed using SPSS 12.0. Homogeneity of variance was tested with the Levene's test (α = 0.05). A log transformation of the data was executed in case the variance proved non-homogenous. Differences among treatments were determined by applying the multivariate general linear model procedure with a Tukey post-hoc test (α = 0.05). Block effects from the tables were accounted for by including table as a random factor.
