Effects of NaCl and Fe-EDDHA concentration on salt toxicity and chemical composition of gardenia (Gardenia jasminoides Ellis) plants EFROSSINI AVRAMAKI1, CHRISTOS CHATZISSAVVIDIS2 and IOANNIS PAPADAKIS1 1 Department of Horticulture, School of Agriculture, Aristotle University, 54 124 Thessaloniki, Greece 2 Department of Agricultural Development, Democritus University of Thrace, 68 200 Orestiada, Greece Abstract Young gardenia (Gardenia jasminoides Ellis) plants rooted under a fog system were grown in black plastic bags containing a sand/perlite (1:1) mixture. The plants were irrigated with Hoagland No2 nutrient solution modified to contain three Fe concentrations (0.5, 1 and 2 mg l–1) in the form of Fe-EDDHA and four concentrations of NaCl (0, 10, 20 and 40 mM). After three months, severe toxicity symptoms were observed on the older leaves (chlorosis of tips and margins) mainly of the plants treated with 40 mM NaCl. Salinity had little effect on leaf P, whereas P concentration of roots increased in the treatments containing 20 or 40 mM NaCl plus 0.5 mg l–1 Fe. Generally, K and Ca concentrations of leaves and roots were not affected by the increase of NaCl concentration in the nutrient solution. In the roots, the lowest Mg concentration was observed in the treatments containing 2 mg l–1 Fe, whereas in the leaves, no significant differences were recorded. Regarding Mn concentration, it was not affected in the leaves but it increased in the roots of the treatments containing 20 and 40 mM NaCl plus 0.5 mg l–1 Fe. Finally, Fe concentration was increased in the roots of the plants treated with 0.5 mg l–1 Fe plus 20 or 40 mM NaCl. Concerning Na concentration, generally, it was increased in the leaves and decreased in the roots of the treatments containing high NaCl plus low or medium Fe concentration.   < back .