Assessment of tolerance of willows to saline soils through electrical impedance measurements

One-year-old potted clone plants of four willow species (Salix matsudana × alba, S. babylonica, S. psammophila and S. cheilophila) were cultivated and irrigated with saline solutions of different concentrations, while their electrical impedance spectroscopy (EIS) parameters and other physical parameters were monitored. The results indicate i) that under salt stress, height and basal diameter of all species are inhibited, and ii) that relative conductivity of cellular exudates increases while intracellular resistance (r _i) and extracelluar resistance (r _e) drop. Both r _i and r _e were positively correlated with height growth and basal diameter while they were significantly and negatively correlated with electric conductivity. The concentration of Na⁺ in the shoots of willows was negatively correlated with both r _i and r _e, whereas the concentration of K⁺ in the shoots was positively correlated with both r _i and r _e. Hence, electrical impedance spectroscopy is a reliable tool for evaluating the capacity of willow species for tolerance to saline soils, with r _i as the most accurate parameter.