Salinity and water deficit are the main abiotic factors that adversely affect the production of economically important crops, especially in the arid and semiarid regions. The objective of the present study was to evaluate sodium chloride (NaCl) and poliethyleneglycol (PEG 6000), commonly used to mimic salt and water stress respectively, on the germination of Carthamus tinctorius L. seeds, an oleaginous species from the Asteraceae. Germination occurred on a paper towel roll system, with seven different osmotic treatments (0, "0.450, "0.852, "1.271 MPa), obtained from iso-osmotic NaCl (100; 200 and 300mM) and PEG (188.35; 267.75 and 357.24 g/L),concentrations. During germination and seedling establishment, the germination rate (%), germination rate index (IVG), relative root growth index (ICRR) and seedling axis fresh weight were measured. The NaCl induced "0.450 MPa osmotic treatment did not result in significant changes in the germination rate and IVG compared to the controls, whereas these parameters were reduced and slightly increased respectively, with the same osmotic pressure induced by the PEG application. The ICRR and the seedling fresh weight showed steep reductions as osmotic pressure fell in both NaCl and PEG induced treatments. It can be concluded that the germination of C. tinctorius seeds is influenced in a stress and dose-specific manner. Moreover, the PEG induced osmotic stress is more aggressive than that induced by NaCl, and lower osmotic pressures (-0.851 and "1.271 MPa) limit germination of this species.
safflower; salinity; water deficit; biofuels
