Effect of salinity and seed salt priming on the physiology of adult plants of Solanum lycopersicum cv. ‘Río Grande’

NaCl priming of seeds can improve seed germination and seedling growth and increase the tolerance to salinity, but most research on salt tolerance in priming plants is restricted to the germination and seedling stages. The aim of this study was to evaluate the effect of soil water salinity and seed salt priming on the physiological responses of adult Solanum lycopersicum Mill. ‘Rio Grande’ plants. A group of seeds was germinated in freshwater (control), and another group was germinated in an 85 mM NaCl solution (salt priming). Plants from both groups were grown during a period of 8 weeks in hydroponic culture. Subsequently, control and priming plants were divided into two subgroups. One subgroup was kept in freshwater, while 85 mM NaCl was added to the nutrient solution of the second subgroup. Tissue water relations, gas exchange, fluorescence and growth parameters were obtained at 0–15 days after the beginning of the experiment. The addition of NaCl to adult plants led to a reduction of leaf solute potential, photosynthetic maximum carboxylation and transpiration rates, and stomatal conductance but neither the chlorophyll content nor any of the parameters associated with the growth of the plant were negatively affected. Salt seed priming induces physiological changes such as improved osmotic adjustment, maximum quantum yield of photosystem II and, partially, the water use efficiency, characteristics that are considered to improve tolerance to salt stress.