This study examined the combined effects of drought stress and combined fertilizer on maize yield and physiological features in Iran's Bam and Fahraj regions. The experiment used a split-plot design with randomized blocks in three replications. Irrigation treatments were applied at three levels: control (-3 bar), moderate stress (-7 bar), and severe stress (-11 bar). Fertilizer treatments included control (no fertilizer), chemical fertilizer (300 kg N + 150 kg triple super phosphate ha⁻¹), biofertilizer (phosphate Barvar-2 and Nitroxin 100%), vermicompost, and combined fertilizer treatment (50% chemical fertilizer + 100% biofertilizer). The results showed that combined fertilizer application under optimal irrigation conditions had the highest impact. Grain yield in Bam region increased from 5,640.6 kg/ha in the control condition to 12,341.2 kg/ha in the combined fertilizer treatment, and in Fahraj region from 4,140 kg/ha to 10,840.6 kg/ha. The harvest index under non-stress and combined fertilizer treatment conditions showed the highest levels in Bam (45.94%) and Fahraj (44.21%). With increasing drought stress intensity, the harvest index decreased, reaching 27.61% in Bam under severe stress. The overall conclusion indicates that combined fertilizer management is an effective strategy for increasing drought tolerance and improving corn performance in arid regions. The combination of chemical and biological fertilizers was able to reduce the negative effects of drought stress and improve crop production efficiency.
Saljughian et al. (Fri,) studied this question.