Water-use efficiency decreased from 4.0 to 2.6 mmol mol−1 with decreasing salinity at 0 μM Si treatment (two-way ANOVA: salinity, p < 0.001; Fig. 2D), although it was not affected in plants supplied with silicon. At 680 mM NaCl WUE was significantly higher in plants grown with 500 μM Si addition (t-test, p < 0.05).
Pigment concentrations (Chl a, Chl b and Cx + c; Fig. 3A–C) increased with increasing salinity concentration at both Si concentrations (two-way ANOVA for each pigment: salinity, p < 0.001; Si, p < 0.001). Under saline conditions plants treated with Si had increased pigment concentrations (t-test, p < 0.01).