This study was divided into two parts, the first part was carried out in vitro to examine the ability of six salt-tolerant PGPR isolates to colonize of two pepper cultivars roots namely Romy and Qarn Ghazal. Then, choosing one of these cultivars for greenhouse experiment. The second part was conducted in the experimental farm station of Fac. Agric. at Moshtohor during 2011 season to alleviate the ability of the selected PGPR isolates (Bacillus megaterium D159, Paenibacillus alvie D139 and Azospirillum lipoferum D207) in combination with compost and humic acid to increase resistance of cultivated pepper under saline stress conditions and improve its productivity. The highest significant increase of macronutrients (N, P and K) uptake and photosynthetic pigments was observed in pepper inoculated with biostimulant combined with humic acid + compost. The application of humic acid combined with compost significantly decreased the proline content in pepper. On reverse, amino acids, sugars and phenols were increased with the application of PGPR combined with compost and/or humic acid.
Key words: Colonization, PGPR, saline stress, proline, humic acid and pepper.