Abstract

Soil salinization is an environmental problem that many world regions must fight; it is one of the major plants abiotic stress factors. In fact, in addition to mineral imbalance and toxicity of certain ions, salinity causes, in consequence of osmotic pressure increase, water absorption decrease which leads to stress. In the current study, the behavior and response of two Atriplex species, A. halimus L. and A. canescens, (Pursh) Nutt. under effect of high salt concentrations (400 and 600 meq of NaCl + CaCl₂) and seawater at 25, 50 and 100% dilutions, were studied, using proline as metabolic marker in relation to resistance to salinity. Three-month-old Atriplex plants were subject to the various salinity levels. The amount of proline was determined from different plant organs after three weeks stress period. The results revealed a metabolic variability characterized by proline accumulation as function of the species, plant organ, and the concentration and nature of salt treatment. In general, the accumulation of proline within the plant occurs in proportion to the medium salt concentration. Indeed, on one hand, the recorded proline contents show that this accumulation is very important in Atriplex canescens (Pursh) Nutt, compared with Atriplex halimus. On the other hand, these contents are high in leaves of both species in presence of high NaCl + CaCl₂ and seawater concentrations.

Key words: Atriplex, salt stress, proline, tolerance, halophyte.