High carbonate content in soil negatively affect plant growth, because the availability of nutrients is restricted due to high pH. The present investigations were carried out to reveal possible alleviating effects of the exogenous root inoculation PGPRs on development and physiology of soilless-grown grapevines cultivated under alkaline stress in controlled glass house. pH of growth medium was increased from 7.5 to the values ranging from 7.9 (control) to 8.1 (A18) according to the bacterial inoculations by NaHCO₃ supplementations. Bacteria inoculations did not result in statistically significant differences in pH values of growth media. The bacterial population density found in the rhizosphere of grapevines ranged from 6 × 10⁸ CFU mL⁻¹ (M-3) to 9 × 10⁸ CFU mL⁻¹ (Ca-637). The highest value of shoot thickness was obtained from Ca-637 (5.3 mm), followed by A18 (5.2 mm), while M3 did not significantly affected the shoot thickness. The greatest pruning residue per vine was obtained from A18 treatment (81.5 g), followed by Ca-637 (80.8 g) while the lowest value was determined in control. Vine yield was the greatest with A18 (1128 g) treatment and was followed by Ca 637 (1059 g). Considering the general observations, root inoculation of PGPRs A18 and Ca-637 may be recommended in enhancing bioremediation of alkali growth media.

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