Does seed treatment with glycinebetaine improve germination rate and seedling growth of sunflower (Helianthus annuus L.) under osmotic stress

Sunflower (Helianthus annuus L.) cv Suncross and Gulshan-98 achenes were germinated in Petri-plates containing filer papers moistened with solution of polyethylene glycol, PEG-8000 (control and osmotic potential -0.6, -1.2 MPa) with and without glycinebetain (GB) application (0,25 and 50 mM). PEG treatment severely reduced germination percentage and fresh and dry biomass and mean germination time (days to 50% germination) in both sunflower cultivars. Addition of GB in growth medium was not effective in alleviating the adverse effects of osmotic stress on germination percentage, mean germination time and seedling dry biomass. In contrast, a slight increase in seedling fresh biomass was observed by the application of 25 mM GB under control and osmotic stress.