2019 Volume 66 Issue 1 Pages 1-8
The salinity tolerance mechanisms of rosemary and thyme were compared regarding the selective absorption of K over Na by the roots (SAK.Na) and the selective transport of K over Na from the roots to the stems [STK.Na(roots/stems)] and from the stems to the leaf blades [STK.Na(stems/leaf blades)]. Plants were cultivated in non-salinized (control) or salinized (ECe = 3 or 6 dS m−1) soil. In rosemary and thyme, whole-plant dry weight decreased only following the ECe 6 treatment. In rosemary, SAK.Na increased after both salinity treatments, but more so for the ECe 3 treatment. STK.Na(roots/stems) was unaffected by ECe 3, but decreased in response to ECe 6, while STK.Na(stems/leaf blades) was unchanged by salinity stress. In rosemary, the suppressed selective absorption of K over Na by the roots under high-salt conditions may have inhibited the selective transport from the roots to the stems, ultimately decreasing dry matter. In thyme, SAK.Na increased in response to the ECe 3 and ECe 6 treatments. STK.Na(roots/stems) increased only for the ECe 3 treatment, while STK.Na(stems/leaf blades) decreased only for the ECe 6 treatment, although not significantly. In thyme, the increased selective absorption of K over Na by the roots may stabilize the selective transport from the roots to the stems at the control level; a decrease in the selective transport from the stems to the leaf blades may contribute to a decrease in dry matter due to an ionic imbalance.
