Salinity and type of salt effects on seed germination characteristics of medicinal plant Zygophyllum album L. (Zygophyllaceae) native to the Algerian Sahara

Zygophyllum album L. known as "Agga" in vernacular Algerian dialect is one of great traditional remedies used by the native populations, as a treatment for skin diseases, indigestions and diabetes. This medicinal specie is drought resistant and salt tolerant, it plays an important role against desertification, reforestation of degraded lands and soil rehabilitation. Therefore, knowledge of environmental requirements for its seed germination is necessary for plant establishment in field conditions to colonize new territories. The main objective of this paper is to evaluate the influence of salinity level and the type of salts on seed germination characteristics (germination percentage and salinity tolerance index) of this shrub found in the Sahara of Algeria. The test was conducted in a phytotron at a temperature of 25 °C and in the dark for 10 days. The seeds germinated in Petri dishes soaked with aqueous solutions of (NaCl, CaCl2 or Na2SO4) at the same concentrations of 0, 100, 150, 200, 250, 300, 350 and 400 mM. Statistical analysis revealed that germination characteristics were significantly affected by salinity level and salt compositions. Seeds of Z. album were non dormant, exhibited highest germination percentage (100 %) under distilled water and were moderately salt tolerant. Both germination percentage and germination velocity gradually decreased with increasing salinity, irrespective of applied salt types. The salts that induced the inhibition of germination were salt specific and decreasing in following sequence: Na2SO4 > CaCl2 > NaCl. Our results support the statements that different salts exhibit both osmotic stress and ionic toxicity on seed germination.