Fig. 3. Segregation of root vigor (left panel) and Al resistance (right panel) in a group of 38 B. ruziziensis x B. decumbens F1 hybrids. Root vigor is the total root length (RL) in Solution 1 (200 µM CaCl₂, pH 4.20), adjusted for the effects of stem-cutting biomass and harvest. Aluminum resistance is the stem-cutting-biomass and harvest-adjusted RL in Solution 2 (200 µM CaCl₂, 200 µM AlCl₃ pH 4.20), after removing the variance component caused by differences in root vigor. The two parents are highlighted by black symbols. The two hybrids with contrasting levels of Al resistance that were used for the hematoxylin-staining test (Fig. 4) are designated as "R" for Al resistant and "S" for Al sensitive.