Drought stress, as one of the most important environmental stresses, has a negative effect on plant performance and reduces plant productivity. Biofertilizers can reduce the effects of drought on plants in water deficit conditions. This research was carried out to investigate the effects of biological fertilizers on the biochemical characteristics and growth of maize SC 704 under drought stress in 2022. Five fertilizer treatments including Control, Nitrobacter, Phosphopowerbacter, Potashpowerbacter, and the combination of all three fertilizers were applied under two levels of irrigation (normal irrigation and drought stress) in 6 replications. The results showed that drought stress affected the proline and leaf chlorophyll content and photosynthetic parameters. At the 8-leaf stage, the application of Nitrobacter increased photosynthesis and transpiration content by 37% and 27%, respectively. Also, the combined application of biofertilizers at the tasseling stage resulted in a 38% increase in intercellular CO2 concentration. At the tasseling stage, the combined biofertilizers increased leaf chlorophyll a and proline content by 64% and 110%, respectively, under drought stress conditions compared to the control. In general, the results showed that the use of Nitrobacter in normal irrigation and the combined application of biological fertilizers under drought stress conditions more efficiently affected the parameters that are effective in the determination of final crop yield.

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