Figure 5.

Al exchange rate of cell walls isolated from 1-cm root tips of maize cv Lixis. Cell walls were desorbed sequentially in 50 mm BaCl₂, pH 4.3, for 5, 10, and 15 min, followed by desorption in 33 mm Na₃citrate, pH 5.8, for 5, 10, and 15 min. 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 12 h in the presence or absence of 1.4 mm Si. Bars show sd, n = 4. Significant differences between mean values are indicated by different letters at the P < 0.05 level (Tukey test).