Statistical analysis
Experiment was conducted as three independent trials with four observations for treatment combinations per each trial. Statistical analysis was performed by one-way Analysis of Variance (ANOVA), and when significant differences were detected, the differences among the mean values were identified by Student-Newman–Keul's multiple range test using SAS software with the confidence level at P b 0.05 (SAS, Release 8.01, SAS Institute Inc., Cary, NC). Mean values and standard error of the means are reported.