Objective To identify the optimal maize hybrid and planting density combinations suitable for the Yellow River Irrigation Areas, this study aimed to select high-yield maize hybrids and adopt rational planting densities.

Method Twelve maize hybrids were used as experimental materials in a one-year and two-location variety comparison trial in 2023. Preliminary screening yield of the experimental hybrids were conducted under high planting density conditions. To verify the high-yield stability of the selected hybrids and explore the physiological mechanisms underlying high-yield formation, hybrid-by-density interaction trial was conducted using the two selected high-yield hybrids with three planting density gradients (7.5×10⁴, 9.0×10⁴, 10.5×10⁴ plants/hm²) in 2024. The effects of hybrid and density on maize photosynthetic characteristics, key agronomic traits, grain quality traits, and yield and its components were investigated.

Result The results showed that during the initial screening of 12 tested hybrids at a density of 10.5×10⁴ plants/hm², 'DK 159' and 'SD 660' exhibited the best yield performance, with yields of 15 974.65 kg/hm² and 15 736.09 kg/hm², respectively, representing significant increases of 33.86% and 31.86% compared with the control 'SD 974'. In the hybrid-by-density interaction trial, leaf area index (LAI), plant height and yield increased with increasing density, while SPAD value, crude protein content, crude starch content, kernels per row, 100-grain weight, and kernel weight per ear showed a significant decreasing trend. Compared with 'SD 660', 'DK 159' had significantly lower ear height by 12.02%, and significantly higher SPAD value, crude starch content, 100-grain weight, and grain dry weight per ear by 12.85%, 3.46%, 8.20% and 9.03%, respectively. 'DK 159' showed stronger high-density adaption, yield potential and stability. 'DK 159' achieved the high yield of 14 981.23 kg/hm² at 10.5×10⁴ plants/hm². which was 11.99% and 6.03% higher than that at 7.5×10⁴ plants/hm² and 9.0×10⁴ plants/hm², respectively. Correlation analysis revealed that yield was positively correlated with LAI, plant height, and ear length.

Conclusion This study screened out two high-yielding corn hybrid varieties, 'DK 159' and 'SD 660', from 12 corn hybrid varieties. 'DK 159' exhibited the optimal comprehensive performance in terms of yield, photosynthetic characteristics, yield traits and grain quality when cultivated at a planting density of 10.5×10⁴ plants/hm².