Response of Armeria maritima (Mill.) Willd. and Plantago maritima L. from an Irish salt marsh to nitrogen and salinity

Abstract

SUMMARYTwo experiments on the interaction between salinity and nitrogen supply were carried out on the halophytes Armeria maritima and Plantago maritima. Water potential values ranged from −0.16 MPa to – 5.0 MPa and nitrogen from 0.28 to 280 mg l−1 N. An increase in nitrogen above 2.8 mg l−1 N in the medium in all cases resulted in an increase in growth, though this was not so great at higher salinities. Armeria growth rate was optimal at a higher nitrogen concentration than Plantago and Armeria also accumulated nitrogen in shoots with increasing salinity. Plantago root nitrogen concentrations increased with increased nitrogen.Both species accumulated sodium in shoots, but in Armeria concentrations were lowest in the highest nitrogen treatments. Potassium was redistributed from shoots to roots with increasing salinity.Two populations of Plantago from the salt marsh were examined. Differences in growth response and flowering time were observed. A third, inland population of Plantago showed reduced vigour in water potentials lower than −2.5 MPa.