Besides, PEG-6000 is large enough so that it does not penetrate membranes and thus stays in apoplast fluid (Huang and Song, 2013). Therefore, in this work, the effects of silicon on the germination characteristics, production of reactive oxygen species, lipid peroxidation, antioxidant defense responses, and phenol level during seed germination of tomato under PEG-induced water deficit stress were investigated. A potential use of silicon fertilizer in water-saving irrigation in tomato in arid or semi-arid regions is discussed.