PEG-osmotic treatment in tomato seedlings induces salt-adaptation in adult plants

Abstract

Complete immersion of 5-day-old tomato seedlings (Lycopersicon esculentum (L.) Mill.) for 12 h in low osmotic potential PEG solutions (-0.5, -0.75 and -1 MPa) induced greater vegetative growth of adult plants under 100 mМ NaCl conditions, as well as adaptive physiological responses concerning ionic, nutritional and osmotic regulation. After 6 weeks of salt-treatment the PEG-treated plants produced up to 50% more biomass and accumulated 1.5- to 2-fold more Na⁺ and Cl⁻ and up to 25 mМ more K⁺ in the actively growing leaves than did the non-treated control plants. Moreover, the most productive PEG-treated plants also registered up to 40% lowered leaf osmotic potential, twice as much proline, and 10% lower leaf water content than the control plants cultivated under salinity. The viability of the method used, the implication of the induced physiological responses on salt adaptation and possible explanations are discussed.