Growth and Ionic Concentration of Eggplant as Influenced by Rootstocks under Saline Conditions

The study was conducted to envisage the influence of various rootstocks on growth and ionic concentration of eggplant (Solanum melongena L.) under salt stress. Eggplant seedlings ('Black bell') were grafted onto three different rootstocks, i.e. 'Beaufort' F-1, 'He-Man' F-1 [tomato interspecific hybrids (S. lycopersicum x S. habrochaites)], and Solanum torvum species, while non-grafted plants were used as control. Salinity treatments consisted of a control (non-saline-treated) and three salt treatments (15 mM Na2SO4, 30 mM NaCl and 20.5 mM Na2SO4). The use of interspecific hybrids ('Beaufort' F-1, 'He-Man' F-1) only enhanced the growth of eggplant under non-saline conditions compared to non-grafted plants, whereas this positive effect was not observed under salt stress conditions regardless to source of salinity. On the contrary, the growth of eggplant grafted onto 'Beaufort' F-1 was minimum under NaCl salinity. The use of S. torvum did not improved plant growth compared to control under non-saline conditions as well as under salt stress conditions. Although, compared to non-grafted control, the interspecific hybrid rootstocks reduced leaf Na+ concentration by retention of Na+ in root system, these plants seems to be more affected by osmotic effect than toxicity of salts. On the contrary, chloride ions were less retained by the roots and translocated to leaves in higher amounts compared to control, consequently affecting plant growth. S. torvum depicted a reduced capacity to retain Na+ in roots and the ionic concentration of Na+ was maximum in shoots under 20.5 mM Na2SO4 treatment. Slight increases in N concentration were observed with 'Beaufort' F-1 and S. torvum rootstocks under the low Na2SO4 salt treatment. Ca2+ leaf concentrations were reduced by salt stresses in 'Beaufort' F-1 and in S. torvum regardless of the source of salinity and in plants grafted onto 'He-Man' F-1 only under the two salt sulphate stresses. Plants grafted onto 'Beaufort' F-1 and 'He-Man' F-1 showed a higher Mg2+ leaf concentration compared to non-grafted plants and plants grafted onto S. torvum.