Comparative adverse effects of PEG-or NaCl- induced osmotic stress on germination and early seedling growth of potential medicinal plant Matricaria chamomilla

The adverse effects of salinity and PEG-induced water stress on growth of Matricaria chamomilla were assessed at the germination stage using osmotic solution of NaCl (0, -0.175, 0.358, -0.541, -0.716 MPa), and polyethylene glycol (PEG 6000) (0, -0.05, -0.1, -0.2, -0.3 MPa), respectively. Effect of NaCl salinity stress (0, 40, 80, 120 and 190 mM NaCl) at early growth stage of chamomile was also studied. The levels of NaCl and PEG-induced water stress were determined in first experiment. Both seed germination rate and seedling growth reduced with increasing osmotic potential of growth medium either due to NaCl or due to PEG. However, PEG-induced osmotic stress caused more growth inhibition compared with NaCl-induced osmotic stress. Seeds were not germinate at -0.8 MPa of NaCl and -0.4 MPa of PEG. In conclusion, adverse effects of salt stress on germination and early growth of chamomile is due to Na accumulation in addition to its osmotic stress.