Figure 6.

Effects of Ca²⁺ on growth and cation accumulation in 6-week-old Arabidopsis plants grown hydroponically in 50 mm NaCl after the 3rd week of planting. a, Shoot dry mass; b, shoot Na⁺ concentration; c, ratio of shoot K⁺ to Na⁺ concentration; d, ratio of shoot Na⁺ to Ca²⁺ concentration. Data represent means, and error bars the se (n = 24). Measurements were only made on surviving plants. To incorporate into the data the different mortalities with different treatments, shoot mass data (a) were multiplied by a “survival factor” of 0.58 for 0.05 mm Ca²⁺ activity treatment (14 of 24 plants survived the 50 mm NaCl treatment), 1 for 0.2 mm Ca²⁺ treatment (24 of 24 plants survived), and 0.875 for the 3.0 mm Ca²⁺ treatment (21 of 24 plants survived). Shoot mass includes the amount of Na⁺ in the tissue, but this accounted for 15.6%, 7.4%, and 3.0% of the total dry mass in the three Ca²⁺ activities used, having no significant effect on the overall trends. Ion concentrations in b to d were measured only in surviving plants and expressed on a dry weight basis for those plants, with no correction for survival.