Seed germination requirements and responses to salinity and water stress of Centaurea eriophora

Abstract

Centaurea eriophora L. (Asteraceae) is a rare annual plant, found in some Mediterranean regions and requiring conservational measures. The present study was carried out to highlight the species germination behavior under two controlled environmental constraints: salt and water stress. Achenes collected on Mount Tessala (North-West Algeria) were germinated under a water potential gradient (0 to –2.45 MPa) induced by different concentrations of polyethylene glycol and under different concentrations of NaCl (0 to 102 mM). The experiments were conducted at constant temperature. The obtained results showed a high significant effect of salinity and water stress, especially on final germination percentage, while the highest germination (85%) was obtained at control conditions in both of the tests. Under salinity and water stress conditions, there was a significant deterioration in most germination parameters, particularly a lower final germination percentage. The tolerance thresholds for salinity and water deficit were 68 mM and –1.2 MPa respectively. Beyond these values, seed germination of C. eriophora was completely inhibited. The sensitivity of C. eriophora achenes to environmental pressures should be considered in the long-term effective conservation plans.