Does compatibility of wheat cultivars with Azospirillum brasilense strains affect drought tolerance?

Due to various physiological outcomes from different symbiosis combinations of wheat cultivars (Triticum aestivum L.) with Azospirillum brasilense strains, evaluation of compatibility of wheat cultivars with bacteria strains is essential to assess the improvement of wheat tolerance to drought condition. So, under control condition (80% of field capacity), the rate of compatibility of six wheat cultivars inoculated with A. brasilense Sp7 (as standard) or Sp245 (produce more abscisic acid) strains was determined based on the growth and biochemical parameters. According to the result Roshan-Sp245, Shahpasand-Sp7, Roshan-Sp7, and Shahpasand-Sp245 as the most compatible, most incompatible, less compatible and less incompatible were determined, respectively. In another experiment, selected combinations were compared at drought condition (40% of field capacity). All physiological parameters were significantly (P ≤ 0.05) affected due to compatibility or drought conditions. In average, under drought condition, root lengths affected positively in Roshan (tolerant) and negatively in Shahpasand (sensitive) cultivars inoculated with different strains of bacteria. Although, shoots protein significantly correlated with compatibility (r = 0.94), number of root branches correlated more with drought tolerance (r = 0.98). In Roshan-Sp245 as compatible pair, enzyme activity of TAL (tyrosine ammonia lyase) in roots, number of root branches, root’s protein, shoot’s PAL (phenylalanine ammonia lyase enzyme) and TAL activities were increased. In contrast, in Shahpasand-Sp7 as incompatible pair, these parameters decreased or did not change under drought condition. Therefore, higher tolerance to drought was obtained through the compatibility of associated pairs. However, significant correlation between compatibility, drought tolerance (r = 0.77) and different parameters were observed.