Number and distribution of nodules on the root system over time in the nine genotypes and N₂-fixation specific activity of nodules. Number of nodules from 6 to 23 days after transplantation (A) and at harvest (B). Percentage of nodules located on the primary root from 6 to 23 days after transplantation (C) and at harvest (D). Mean specific activity of nodules during the 23 first days of growth (E). The 95% confidence interval with local regression adjustment was drawn in transparency. In the boxplots, letters indicate significant differences among genotypes (Tukey’ ́s HSD test. P < 0.05).