2.8. Statistical analysis
Analysis of variance (ANOVA) and the test of mean comparison
according to Tukey’s honest significant difference (HSD)
were conducted with the level of significance of 0.05. The statistical
software, SAS System for windows, version 9.0 (SAS institute,
Cary, NC), was used for the analysis. The parameters of
nonlinear model were calculated using SigmaPlot (Scientific
Graphing Software, version 3, Jandel Corporation).