Ameliorative effects of inoculation with Serratia marcescens and grafting on growth of eggplant seedlings under salt stress

Grafting on a moderate salt-tolerant rootstock (Vista-306) and bacteria (Serratia marcescens) inoculation were tested whether grafting and bacteria can alleviate salinity stress in eggplant. Two salt-tolerant eggplant genotypes ('Mardin Kiziltepe', 'Burdur Merkez') and two salt-sensitive eggplant genotypes ('Artvin Hopa', 'Kemer') were used as scions. Grafted and non-grafted seedlings with 4-5 true leaves were transferred to pots filled with a mixture of peat: perlite (2:1) in a controlled greenhouse and were cultivated under temperatures of 23-25 degrees C with approximately 50-55% relative humidity. After 10 days from planting, 20 mL bacteria solution (cell density of 3 x 10(8) cells mL(-1)) per plant was applied to the root region of the seedlings as inoculum. 200 mM NaCl solution was applied to plants for 20 days after 5 days from inoculation of the bacteria. The study was arranged in a randomized block factorial design with three replicates. The grafted seedlings induced salt tolerance registering lower foliar concentrations of Na+ and Cl-, the lower lipid peroxidation and higher antioxidative enzyme activities. Inoculation of the bacteria significantly counteracted the salt-induced adverse effects on growth characteristics, leaf Cl-, Na+ contents, and antioxidative enzyme activities. In conclusion, grafting and inoculation with Serratia marcescens are effective in improving growth and some key physiological processes in eggplant under salt stress.