Figure 6.

Fluorescence of the morin-Al complex in root cross-sections of maize cv Lixis 1 to 3 mm behind the root tip. Plants were precultured in a solution containing 500 μm CaCl₂ and 8 μm H₃BO₃, pH 4.3, for 36 h without or with 1.4 mm Si and then treated without or with 25 μm Al for 1 h in the presence or absence of 1.4 mm Si. Excitation filter 395 to 440 nm, barrier filter 470 nm. A to C, Cross-sections from the root zone 1 to 2 mm behind the root tip. A′ to C′, Close-up of Al staining of epidermal and cortical cells in A to C, respectively. A″ to C″, Close-up of Al staining of epidermal and cortical cells in cross-sections from the root zone 2 to 3 mm behind the root tip.