Quantifying seed germination responses of Echinops and Centaurea, to salinity and drought stresses

چکیده مقاله

Seed germination may significantly interrupt by water stress due to drought and salinity condition. Salinity can cause osmotic pressure and induce drought stress. Water deficit stress affect normal seed germination and reduce seedling vigor. The objective of this investigation was to determine the effect of drought and salt stresses on germination characteristics of Echinops ritro and Centaurea virgata. Seeds were germinated with the concentrations of sodium chloride (0, 50, 100, 150 and 200 mmol) or in polyethylene glycol PEG6000 (0, -0.2, -0.4, -0.6, -0.8, -1 and -1.2 MPa). The highest values of germination parameters were obtained with no osmotic potential or salinity stress. At treatment by PEG, the germination was severely decreased at -0.6 MPa. While, no germination occurred at- 0.8 MPa by PEG. Results revealed that under 118 Mmol salinity, the seed germination of Centaurea virgata declined to 43% which was as close as half of its total seed germination. However, 50% reduction in seed germination of Echinops ritro was observed at 193 mmol salinity. Results indicated Echinops ritro and Centaurea virgata germination was sensitive to both the stresses. However, seedling growth was more sensitive to PEG than NaCl.