Abstract
To investigate the relationship between aluminum tolerance and the binding capacity of the root plasmalemma for aluminum, root sections were stained with methylene blue and the blue color intensity of protoplasts was measured with a multi‐purpose graphic analyzer connected to a personal computer. Methylene blue stained both the cell wall and the protoplasts. Root sections killed in boiling water were stained with the same intensity as living root sections.
Aluminum tolerance of rice, oats, maize, pea, and barley were correlated with the electric negativity of protoplasts of the outer cortex as determined by staining with methylene blue. Electric negativity of the plasmalemma, especially in the tip and the outer portions of the root, may determine differential aluminum tolerance among plant species.