Study of associative relationship effects of Azospirillum brasilense (Sp7 and Sp245) on some growth and biochemical indices of wheat seedlings under saline conditions

Salt stress is one of the most serious environmental factors limiting the productivity of wheat plants. it is demonstrated associative relationship is one of the ways to decrease the detrimental effects of the saline condition. This study was carried out to determine the suitable bacteria strains and concentrations in 4 Iranian cultivars wheat (Sardari, Chamran, Shole and Roshan). Experiment was established as factorial on completely randomized design with three replicate to investigate effects of two levels of salinity (0 and 200 mM) and five concentrations (0, 105, 106, 107 and 108 CFU/ml) of both bacteria strains (Sp7 & Sp245) on some growth and biochemical indexes of wheat cultivars. Results showed dry weight, K+ content and chlorophyll a and b reduced with salinity while Na+ content, Na+/K+ ratio and antioxidant enzyme activities (Catalase, Ascorbate peroxidase, Phenylalanine and Tyrosine ammonia lyase), in most cases, significantly increased. The best associative relationship of both strains mainly was seen in 106 and 107 CFU/ml concentrations. At saline condition, Sp245 considerably improved root indexes whereas positives effects of sp7 mostly were observed in shoot indexes. Altogether, reduction in unfavorable effects of salinity on Sardari and Chamran cultivars after inoculation with Sp7 strain were markedly higher than Sp245 strain performance.