Effect of Seed Priming on Physiological Changes in Tomato Grown under Salt Stress

Seed priming has been reported to be an economical and simple cultural technique for increasing the tolerance capacity of plants to salinity. The present study was carried out to assess the effects of seed priming with various kinds of priming solutions on some physiological changes of 7-week-old tomato plants grown under saline condition. Seeds of tomato (Lycopersicon esculentum Mill. 'Sida') were primed with distilled water, 1% H2O2, 50 mM CaCl2 center dot 2H(2)O, 2% mannitol, 25 ppm kinetin, 3% KNO3, 50 ppm salicylic acid, 50 ppm ascorbic acid, 18 dm(-1) NaCl and 0.5% KH2PO4 for 2 h to 6 days. The levels of malonyldialdehyde (MDA), hydrogen peroxide (H2O2), proline and total chlorophyll were determined from leaves of control and 150 mM NaCl-treated plants. NaCl stress increased the amount of MDA, H2O2 and proline but reduced the amount of chlorophyll. The increment of MDA levels in seedlings arising from kinetin-and ascorbic acid-primed seeds were significantly lower than the other treatments. In addition, seed primed with kinetin, KNO3, NaCl, KH2PO4 and CaCl2 center dot 2H(2)O showed the lowest percentage of increase in H2O2. Treatment of seeds with mannitol and KH2PO4 resulted in the lowest and highest changes in proline level, respectively. All priming treatments showed similar effects on the reduction of chlorophyll content. Based on the changes in physiological indicators measured, kinetin-priming treatment would be the most effective method to increase salt tolerance by significantly lowering the level of lipid peroxidation and H2O2 production under NaCl stress.