Research on the yield-enhancing mechanisms of maize through ‘smart' plant morphology under dense planting conditions is a critical focus in modern agriculture.  However, the issue of yield stability in densely planted maize, particularly regarding lodging resistance, remains insufficiently examined in the literature.  A three-year field experiment was conducted using three hybrids (XD20, DH618 and DH605) and three plant density treatments (6.0×10⁴, 7.5×10⁴, and 9.0×10⁴ plants ha^–1) to investigate the effects of planting density on the lodging resistance and yield of summer maize hybrids with different plant morphologies.  According to the results, increasing the planting density significantly boosted the yield of DH605, while the yields of XD20 and DH618 exhibited initial increases followed by stabilization.  Compared to the low-density (L) treatment, the height parameters and center of gravity of summer maize under the high-density (H) treatment were significantly elevated.  This was accompanied by a pronounced reduction in light transmittance within the bottom and ear layers, a reduction in the mechanical strength of basal internodes, and an increased risk of lodging, particularly for the XD20 hybrid.  DH605 improved mechanical strength by enhancing the light distribution within the ear and bottom layers, and by optimizing basal internode characteristics.  Ultimately, the grain yield under the DH605-H treatment increased by 10.68 to 34.11% relative to XD20-H, with a concurrent reduction in lodging rates ranging from 72.66 to 92.29%.  Cellulose content within the basal internodes and the total area of vascular bundles in the outer layer were key factors, explaining 61.70% of mechanical strength variance.  Therefore, a high planting density significantly increased the yield but also lodging susceptibility.  Optimizing plant morphology improved the canopy light distribution, dry matter composition and anatomical structure of basal internodes, thereby enhancing lodging resistance and grain yield in densely planted maize.

maize  /  planting density  /  plant morphology  /  canopy light distribution  /  lodging resistance