Priming of seeds with NaCl induces physiological changes in tomato plants grown under salt stress

The effects of seed priming with 6 M NaCl solution have been investigated with respect to growth and physiological responses of tomato plants (Lycopersicon esculentum Mill. cv. Pera) exposed to 70 and 140 mM NaCl nutrient solutions from 11 to 60 days after sowing. Tomato seedlings from primed seeds emerged earlier than from non-primed seeds. At 70 mM, a lower shoot and root dry weight reduction was found in plants from primed seeds at the different harvests (30, 45 and 60 days after sowing), while at 140 mM the positive effect of seed priming was only shown in roots. Significant changes in Na+ and Cl- accumulation with seed priming were only found in roots at 60 days after sowing, with ion accumulation in roots being higher in plants grown at 70 and 140 mM from primed seeds. In leaves of salt-treated plants, significant increases in sugars and organic acids with seed priming were found from 30 days after sowing, and these increases were higher at longer treatment times. In roots, however, only the organic acids tended to increase in plants from primed seeds, although they increased less than in leaves, especially at 60 days after sowing. These results support the hypothesis that priming of seeds with NaCl induces physiological changes in the plants, changes which are shown more clearly at advanced growth stages.