2.5 Statistical analysis
Physiological data were analyzed using the SPSS 17.0 software (SPSS Inc., Chicago, IL, USA). Significant differences among the means of different treatments were determined by Tukey’s multiple range tests after conducting tests of homogeneity for variances. Differences were considered statistically significant at the p < 0.05 level. To assess alpha-diversity, communities were rarified to 11 000 (bacteria) and 10 000 (fungi) sequences per sample. Alpha-diversity indexes (Ace index and Sobs index) were calculated using QIIME (Caporaso et al., 2010). The significances of differences among treatments were assessed using the Welch’s t-test. Similarities and differences arising from microbiomes of different soil samples were visualized with Circos (Krzywinski et al., 2009). Bray-Curtis distances between samples were used for principal coordinate analysis (PCoA) to assess the major variance components of the beta-diversity. Permutational multivariate analysis of variance (PERMANOVA) was used to evaluate group differences. Discriminant taxa were significantly retrieved by linear discriminant analysis (LDA) effect size (LEfSe) for bulk-soil and rhizosphere-microbial communities (Segata et al., 2011).