Table II.

Effects of N form and nutrient solution pH on concentration, amount, and total Fe uptake of sunflower

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

Treatments Fe concentration Fe Amount Fe Uptake
Roots Leaves Roots Leaves
μg g-1 dry wt μg organ-1 μg plant-1
NO3-; pH 5.0 (green) 266 ± 20a 81 ± 11a 39 ± 3a 34 ± 4a 81 ± 7a
NO3-, 40 mm; pH 5.0 (green) 245 ± 34a 78 ± 8a 35 ± 12a 38 ± 5a 79 ± 8a
NO3-; unbuffered (chlorotic) 175 ± 30b 49 ± 4b 22 ± 4b 19 ± 2b 45 ± 2b
NH4+; pH 5.0 (green) 318 ± 28a 100 ± 14a 26 ± 5a 25 ± 3ab 58 ± 5ab
NH4+; pH 7.5 (chlorotic) 207 ± 36b 34 ± 3c 10 ± 2c 9 ± 1c 23 ± 4 c
NH4NO3; unbuffered (green) 239 ± 44ab 85 ± 10a 33 ± 2a 42 ± 6a 83 ± 6a
NH4NO3; pH 7.5 (chlorotic) 229 ± 51b 35 ± 4c 9 ± 1c 8 ± 1c 21 ± 2c