Salt-tolerant genotypes and halotolerant rhizobacteria: A potential synergistic alliance to endure high salinity conditions in wheat

The interaction of salt-resistant and salt-sensitive wheat varieties with halotolerant bacterial strains has not been well understood. In a greenhouse experiment, the effect of three halotolerant bacterial strains ( Bacillus safensis AL, Bacillus pumilus HR, and Zhihengliuella halotolerans SB) on yield and morphological and biochemical traits of two wheat varieties (Qods, a salinity sensitive variety, and Narin, a salinity resistant variety) under different salinity levels (0, 40, 80, and 160 mM NaCl) was investigated. The results showed that salinity had a negative effect on all morphological and biochemical traits of both varieties. At all salinity levels, especially at higher levels of salinity (80 and 160 mM NaCl), the effect of bacterial strains on the growth indices of Narin variety was better than Qods variety. At 160 mM NaCl level, bacterial strains caused an increase of 10–45% in seed, stem, and root dry weight, K + /Na + ratio, P and Ca content, chlorophyll a , crude protein, and seed amylose and amylopectin content of Narin variety compared to Qods variety. At 160 mM NaCl level, these bacteria also increased the 2,2-Diphenyl-1-picrylhydrazyl radical scavenging capacity by 21%, phenol content by 32%, and proline content by 6% in Narin variety compared to Qods variety. Higher grain yields were observed in the Narin variety inoculated with B. safensis AL and in the Qods variety inoculated with Z. halotolerans SB at all salinity levels. However, bacterial performance was variable, depending on salinity level and variety. The content of seed amylose and amylopectin in Qods variety was higher than Narin variety. In general, the Narin variety inoculated with bacterial strains in this study showed a better response to salinity stress than Qods variety. This can be a challenge for producing biofertilizers for varieties whose resistance to salinity is unknown. Overall, the results of this study emphasize on considering the best bacterial strain-wheat variety-salinity level combination to increase wheat yield. • Salt resistant variety inoculated with bacteria showed a better response to salinity than salt sensitive. • The content of seed amylose and amylopectin in salt sensitive variety was higher than salt resistant variety. • This study showed a challenge for producing biofertilizers for varieties whose resistance to salinity is unknown. • To increase wheat yield under salt stress, the best bacterium-wheat variety-salinity level combination should be selected.