Exogenous application of zinc mitigates the deleterious effects in eggplant grown under salinity stress

The present study was conducted to investigate the effects of Zn application to salt stressed eggplant (Solanum melongena L.) seedlings grown in vitro and whether it can alleviate the deleterious effects of salinity or not. Zinc (0, 5, 10 and 20 mg/L) and sodium chloride (NaCl) at different concentrations (0, 50, 100 and 150 mM) were added to solidified half strength MS medium placed in 250 mL glass jars. The treatments were arranged in a 4 x 4 factorial experiment in a completely randomized design with four replications. Application of Zn to growing seedlings at different concentrations (5, 10 or 20 mg/L) increased the length of shoot and root and their dry weights, as well as enhanced the photosynthetic pigment contents and leaf relative water content compared to control. However, the application of NaCl to growing seedlings at different concentrations (50, 100 and 150 mM) significantly reduced the above mentioned attributes compared to control and those of Zn treatments alone. Treatment of seedlings with either Zn (5, 0 or 20 mg/L) or NaCl (50, 100 or 150 mM) significantly increased the proline content and the antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX) in growing seedlings. However, the application of Zn to salt stressed seedlings mitigated the deleterious effects of salt stress in growing seedlings and increased the tolerance of seedlings to its deleterious effects.