Table IV.

Effects of N form and nutrient solution pH on absolute and relative (share of total Fe) concentrations of symplastic and apoplastic Fe fractions in sunflower leaves

Data are means ± sd of four replications. Significant differences (P < 5%) between treatments are indicated by different letters.

Treatments Symplastic Fe Apoplastic Fe
Absolute Relative Absolute Relative
μg g-1 dry wt % μg g-1 dry wt %
NO3-; pH 5.0 (green) 67.4 ± 3.2a 73 24.7 ± 2.7a 27
NO3-,40 mm; pH 5.0 (green) 54.1 ± 3.2a 72 21.5 ± 3.2a 28
NO3-; unbuffered (chlorotic) 42.1 ± 5.0b 76 12.9 ± 2.0b 24
NH4+; pH 5.0 (green) 58.3 ± 14.4a 75 18.3 ± 1.8a 25
NH4+; pH 7.5 (chlorotic) 29.0 ± 2.8c 72 11.4 ± 1.3b 28
NH4NO3; unbuffered (green) 63.8 ± 5.0a 72 24.1 ± 5.6a 28
NH4NO3; pH 7.5 (chlorotic) 35.3 ± 3.3c 74 12.2 ± 1.0b 26