Figure 6.
Effects of crown root diameter on dissolved oxygen (DO) levels near the root tip. a–d) Representative cross-sectional images of crown roots at 50 mm from the root tip for each cultivar. Scale bars = 200 µm. e) Average crown root diameter of emerged roots at 21 days after sowing. Bar plots represent mean ± Sd (n = 3 or 4 plants). Different letters indicate significant differences among cultivars (P < 0.05, Tukey's multiple-comparison test). f–h) Relationships between crown root diameter and maximum DO levels in the root tip region (0 to 30 mm) for each cultivar across different root-length classes. The numbers above the panels indicate the corresponding root-length classes. Points represent individual measurements, with colors indicating different cultivars. Solid lines indicate cultivar-specific fitted regression lines estimated using linear models (DO ∼ crown root diameter), and shaded areas denote 95% confidence intervals. Regression slopes and coefficients of determination (R2) were calculated for each cultivar (Pearson's correlation analysis, *P < 0.05, **P < 0.01).