FIGURE 2.

Influence of Si supply on ${\text{NH}}_4^{+}$, S, and ${\text{SO}}_4^{2-}$ concentrations in roots and leaves of two contrasting tomato genotypes under osmotic stress. (A) ${\text{NH}}_4^{+}$ concentration in roots, (B) ${\text{NH}}_4^{+}$ concentration in leaves, (C) S concentration in roots, (D) S concentration in leaves, (E) ${\text{SO}}_4^{2-}$ concentration in roots and (F) ${\text{SO}}_4^{2-}$ concentration in leaves. Plants were grown in hydroponic culture and osmotic stress was simulated by applying polyethylene glycol (PEG 6000). Si was provided at 0.75 mM for pre-cultured plants and at 1.5 mM for osmotic stressed plants. Roots and fully expanded leaves from 21-day old plants were harvested 7 days after imposition of osmotic stress. Bars indicate means ± SE. Different letters denote significant differences according to Fischer’s LSD test (p < 0.05; n = 4).