The promising study aimed to determine the most suitable synthetic cultivar of maize (Zea mays L.) under varied effects of mineral fertilizer combinations (nitrogen, phosphate, and potassium) and organic manures. A maize field experiment materialized in the 2022 crop season in the experimental fields of Ibn-Al-Bitar Preparatory Vocational School, District Al-Hussainiya, Holy Kerbala Governorate, Iraq. Employing the randomized complete block design (RCBD) with a split-plot arrangement helped set the experiment. In the main plots, the six combinations of mineral and organic fertilizers used comprised a) 160N + 100P₂O₅ + 40K₂O kg ha^-1, b) 160N + 100P₂O₅ + 40K₂O + 4 t ha^-1 of organic fertilizer, c) 160N + 100P₂O₅ + 40K₂O kg ha^-1 + 8 t ha^-1 of organic fertilizer, d) 320N + 200P₂O₅ + 80K₂O kg ha^-1, e) 320N + 200P₂O₅ + 80K₂O kg ha^-1 + 4 t ha^-1 of organic fertilizer, and f) 320N + 200P₂O₅ + 80K₂O kg ha^-1 + 8 tons ha^-1 organic fertilizer. The six maize synthetic cultivars in the subplots were Fajr-1, Maha, 5018, Sumer, Sarah, and Baghdad-3. The total uptake of nitrogen and phosphorus showed a significant interaction between fertilization levels and maize cultivars. The maize synthetic cultivar 5018 achieved the highest interaction at the sixth fertilizer level, with nitrogen and phosphorus uptake of 348.33 and 69.50 kg ha^-1, respectively. The maize cultivar Baghdad-3 at the sixth fertilizer level achieved the maximum interaction for potassium uptake, grains per ear, biological, and grain yields (213.43 kg ha^-1, 777.50 grains per ear, 20,949 kg ha^-1, and 9,674 kg ha^-1, respectively). However, this interaction was not significantly different from the interaction of the same synthetic cultivar with the fifth fertilizer level for the traits, viz., grains per ear, biological, and grain yields.

Keywords: Maize (Zea mays L.), synthetic cultivars, organic manures, mineral fertilizers, potassium uptake, biological and grain yield, biochemical traits

Key findings: The maize cultivar Baghdad-3, with the sixth level of fertilizer combination, achieved the highest interaction for total uptake of potassium, grains per ear, biological yield, and grain yield. However, this interaction did not differ significantly from the interaction of the same cultivar with the fifth fertilizer level for the grains per ear, biological, and grains yield.