Figure 4.

The effect of 10-min or 3-h pretreatment in sorbitol or PEG (that are iso-osmotic with 50 mm NaCl) on influx of Na⁺ from 1 mm NaCl. All solutions contained 1 mm NaCl and 0.05 or 1.0 mm Ca²⁺ activity in addition to added osmotica. Influx was measured over 2 min into excised roots of Arabidopsis. Na⁺ influx was calculated as a percentage relative to control plants pretreated for 10 min in just 1 mm NaCl plus 0.05 or 1.0 mm Ca²⁺ activity. Data represent means, and error bars the se (n = 4). Numbers below the graph represent the percentage of total Na⁺ influx that was sensitive to a change in external Ca²⁺ activity from 0.05 to 1 mm, calculated according to the formula: [(Na⁺ influx [%] at 0.05 mm Ca²⁺) - (Na⁺ influx [%] at 1 mm Ca²⁺)]. Control fluxes were 74.9 ± 13.2 and 43.4 ± 5.5 nmol ^g-1 min^-1 at 0.05 and 1.0 Ca²⁺ activities, respectively.