Responses of the Tomato (Lycopersicon esculentum Mill.) Plant to Exposure to Different Salt Forms and Rates


Abstract: We aimed to investigate the effects of NaCl and Na_2SO_4 on seed and pollen germination of tomato (Lycopersicon esculentum Mill.) in vitro. In addition, the effects of NaCl, Na_2SO_4, and CaCl_2 on yield and quality, plant growth, some physiological parameters, and the distribution of mineral composition in greenhouse grown tomato plants were investigated. Seed germination was affected by high salinity treatments (MS and 1/2 MS). Pollen germination and pollen tube length were significantly affected by salt forms and doses. Pollen germination was blocked by the above doses of 50 mM NaCl and 30 mM Na_2SO_4. In the greenhouse experiment, with increasing concentration of all forms of salt, stomatal density, chlorophyll content, plant growth, and yield decreased. Reductions were higher in fruit yield and stomatal density in the NaCl treatment than those in Na_2SO_4 and CaCl_2 treatments. Membrane permeability was impaired with increases in all 3 forms of salt concentrations, but the effect of NaCl treatment on membrane permeability was more striking compared to the other salt forms. Proline accumulation increased with increasing salt concentrations. The K and N concentrations decreased with increases in all 3 types of salt concentrations. Concentration of Ca decreased with increasing NaCl and Na_2SO_4, but increased with CaCl_2 salt concentrations. The growth and yield reduction under both NaCl and Na_2SO_4 stress may be due to the combined effects of lower rates of Ca, K, and N, and excess accumulation of Na, while in the CaCl_2 experiment the growth reduction may be related to lower rates of K and N and the high rate of Ca.

Keywords: Tomato, salinity, seed and pollen germination

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