Effect of Seed Priming by Silicic Acid and Sodium Nitroprusside Solutions on Seed Germination and Seedling Growth of Greenhouse Tomato (Lycopersicom esculentum L. cv. Isabella) under Salinity Stress

This investigation was conducted to evaluate the effect of seed pretreatment using silicic acid and sodium nitroprusside on the germination parameters of tomato (Lycopersicom esculentum cv. Isabella) under salinity stress based on a factorial arrangement in a completely randomized design with 5 replications. The first factor, salinity levels, included 0, 25, 50, 100 and 150 mM sodium chloride (0.067, 2.45, 5.44, 9.52 and 14.10 dS m–1, respectively); the second one was the chemical pretreatment of the seed with/without 2.5 mM silicic acid solution (SiA), and the third one was the chemical pretreatment of the seeds with/without 100 mM sodium nitroprusside (SNP). Results showed that, due germination percentage, germination rate, seed vigor index and stress tolerance index were all decreased, but application of SiA and SNP improved some factors in Isabella tomato seed germination. Under saline conditions, the use of SiA and SNP had a significant effect on reducing the effects of salinity in the above-mentioned indices. In general, the negative effects of salinity on the seed germination characteristics could be reduced by pretreating tomato seeds with 100 μM SNP or 2.5 mM SiA solution, alone or in combination, under salinity levels up to 100 mM NaCl (i.e., 9.52 dS m–1).