Effect of salinity on seed germination, seedling growth, and inorganic and organic solutes accumulation in sunflower (Helianthus annuus L.)
Wu, G. -Q.; Jiao, Q.; Shui, Q. -Z.
Plant Soil and Environment 61(5): 220-226
To investigate the effects of saline stress on seed germination, ion distribution, and organic solutes changes of sunflower (Helianthus annuus L.), in the present study, seeds and 3-week-old seedlings were subjected to a series of external NaCl concentrations (5-200 mmol). The results showed that high salinity (200 mmol) remarkably inhibited the germination of seed and delayed germination time in sunflower. It was found that 25-200 mmol NaCl significantly reduced both stem and leaf dry weight. Concentrations of 100 and 200 mmol also caused a clear reduction in tissues water content. With the increase of NaCl concentration, Na+ concentrations both in root and stem showed the increasing trend, whereas to a lesser degree in root than in stem. In leaf, Na+ concentration remained unchanged when the external concentrations of NaCl were below 100 mmol, while significantly increased by 41-fold when plants were exposed to 200 mmol. By contrast, K+ concentration in root displayed the decreasing trend with the increase of NaCl concentrations. Neither lower (5 and 10 mmol) nor higher (100 and 200 mmol) salinity significantly affected K+ concentration both in stem and leaf, while moderate levels (25 and 50 mmol) significantly enhanced K+ accumulation. High salinity significantly enhanced soluble sugar concentration in stem by 28% and proline in leaf by 166%. It was proposed that sunflower plants adapt to saline stress to some extent through regulating distribution of Na+ and K+, maintaining higher selective absorption capacity for K+ over Na+, and accumulating more osmoprotectants, such as soluble sugar and proline.