Fig4. Transgenerational effects of soil salinity on root growth and salt tolerance in individual F1 and F2 populations and matched environments. All boxplots show the interquartile range (IQR; box) ± 1.5xIQR (whiskers), including median (horizonal line) and replication units (dots). (a) Root growth of F1 plants at 0, 50 and 100 mM NaCl. Data represent root growth values (cm) of plants within individual F1 populations over a 5-day period (n=15). P-values indicate statistical significance of parent treatment, F1 treatment and interaction by 2-way ANOVA of pooled F1 populations from similarly treated parents, and nested 2-way ANOVA with F1 population as random factor, respectively. For each NaCl concentration, different letters indicate statistically significant differences between pooled F1 populations from similarly treated parents (ANOVA + Tukey post-hoc test; α=0.05; NS: no significant differences). (b) Root growth of F2 plants at 0, 50 and 100 mM NaCl after one stress-free F1 generation. Data represent root growth values (cm) of plants within individual F2 populations over a 5-day period (n=4-5). P-values indicate statistical significance of parent treatment, F2 treatment and interaction by 2-way ANOVA of pooled F2 populations from a common parental ancestor, and nested 2-way ANOVA with F2 population as random factor, respectively. NS: no statistically significant differences between pooled F2 populations from a common parental ancestor (ANOVA + Tukey post-hoc test; α=0.05). (c) Tolerance of F1 plants to 50 and 100 mM NaCl. Tolerance was quantified by root growth reduction (%) relative to the mean root growth at 0 mM NaCl of the corresponding F1 population (Fig. S4a). Data represent growth reduction percentages of single plants within individual F1 populations (n=15). P-values indicate statistical significance of parent treatment, F1 treatment and interaction by 2-way ANOVA of pooled F1 populations from similarly treated parents, and nested 2-way ANOVA with F1 population as random factor, respectively. NS: no statistically significant differences between pooled F1 populations from similarly treated parents (ANOVA + Tukey post-hoc test; α=0.05). (d) Tolerance of F2 plants to 50 and 100 mM NaCl after one stress-free F1 generation. Tolerance was quantified by root growth reduction relative to the mean root growth at 0 mM NaCl of the corresponding F2 population (Fig. S4b). Data represent growth reduction percentages of single plants within individual F2 populations (n=4-5). P-values indicate statistical significance of parent treatment, F2 treatment and interaction by 2-way ANOVA of pooled F2 populations from a common parental ancestor, and nested 2-way ANOVA with F2 population as random factor, respectively. NS: no statistically significant differences between pooled F2 populations from a common parental ancestor (ANOVA + Tukey post-hoc test; α=0.05).