Ammonium nutrition in the halophyte Spartina alterniflora under salt stress: evidence for a priming effect of ammonium?

• Published in: Plant and soil 2013-09, Vol.370 (1/2), p.163-173
• Main Authors: Hessini, Kamel, Hamed, Karim Ben, Gandour, Mhemmed, Mejri, Maroua, Abdelly, Chedly, Cruz, Cristina
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Ammonia; Ammonium; Ammonium compounds; Ammonium paratungstate; Animal, plant and microbial ecology; Antioxidants; Aquatic plants; Biological and medical sciences; Biomedical and Life Sciences; Cord grass; Ecology; Electrolyte leakage; Environmental aspects; Enzymatic activity; Enzymes; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Health aspects; Hydrogen peroxide; Leaves; Life Sciences; Nitrates; Nitrogen; Nutrition; Oxidative stress; Plant biology; Plant growth; Plant Physiology; Plant Sciences; Plants; Quaternary ammonium compounds; Regular Article; Salinity; Salts; Sandy soils; Sodium chloride; Soil salinity; Soil Science & Conservation; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Spartina alterniflora; Tidal marshes
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-013-1616-1

Background and aims The effects of salt stress on the salt marsh halophyte Spartina alterniflora have been well documented. However, plant responses to combined salinity and ammonium toxicity and the underlying mechanisms are relatively unknown. The aim of the present investigation was to study the effects of both salinity (0, 200 and 500 mM NaCl) and nitrogen form (NO₃⁻, NH₄⁺ or NH₄ NO₃) on S. alterniflora. Methods Plants were cultivated in sandy soil under greenhouse conditions for 3 months. At harvest, growth parameters were measured and leaf samples were analysed for oxidative stress parameters (malondialdehyde, MDA; electrolyte leakage, EL; and hydrogen peroxide, H₂O₂ concentration) and the activity of antioxidant enzymes (glutathione reducíase, GR; Superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX and Guaiacol peroxidase, GPX). Results In the absence of NaCl, plant growth rate was the highest in the medium containing both nitrogen forms, and the lowest in the medium containing only nitrate. Irrespective of the nitrogen form, plant growth was generally higher at 200 mM NaCl than without salinity. Ammonium-fed plants showed better growth than nitrate-fed plants under high salinity. In the absence of salinity, ammonium-fed plants showed higher SOD, APX, GR, CAT, and GPX activities than nitratefed ones. The antioxidant enzymes exhibited higher activity in saline-treated plants. The considerable advantage of NHNH₄⁺ nutrition to S. alterniflora under saline conditions was associated with high antioxidant enzyme activities, together with low MDA content, EL, and H₂O₂ concentration. Conclusion These data clearly demonstrate that NHNH₄⁺ is more favourable for the growth of S. alterniflora under high salinity than NO₃⁻. It is suggested that NH₄⁺ nutrition improves the plant's capacity to limit oxidative damage by stimulating the activities of the major antioxidant enzymes.