Insights into Physiological Responses of the Halophyte Suaeda fruticosa to Simultaneous Salinity and Iron Deficiency

Physiological responses of the halophyte Suaeda fruticosa cultivated under combined effects of salinity and iron deficiency were addressed. Plants were grown hydroponically for one month with a complete nutrient solution containing iron (Fe) of 0 or 30 μM, without or with salinity (100 and 400 mM NaCl). Growth parameters, chlorophyll concentration, mineral status, Fe(III) chelate reductase (FCR) activity and the acidification capacity were evaluated. Fe deficiency restricted significantly the plant biomass production as well as Fe uptake. Interestingly, the exposure to salinity mitigated the impact of Fe shortage on the plant growth whereas the impacts of salinity and Fe deficiency were not additive with respect to the plant Fe status. Salinity had no effect on the root proton release except a slight reduction at 400 mM and the FCR activity. Interestingly, both Fe absorption and use efficiencies were significantly higher in salt‐treated plants under optimal Fe supply. In their native ecosystems, halophytes are challenged with environmental stresses, as e.g. salinity and nutrient deficiency. In S. fruticosa exposed to salinity and Fe shortage, no additive effects could be observed and the adverse impact of Fe deficiency on plant growth was even mitigated by salt stress. Interestingly, the plant aptitude to acidify the rhizosphere and the Fe3+ reduction plant capacity were unaffected by salinity, associated with higher Fe absorption and use efficiencies for plant growth.