A study on response of planting density to 3D plant shape plasticity and population light transmittance of maize

1. During vegetative growth, maize exhibited enhanced vertical and horizontal development under increased planting density. 2. At silking stage, plants showed reduced spatial occupancy with pronounced lateral growth inhibition under increased planting density. 3. The light transmission model based on support vector regression achieved reliable prediction accuracy. Traditional two-dimensional analyses of maize ( Zea mays . L) plant architecture plasticity and canopy light transmission under varying planting densities have limitations in capturing spatial heterogeneity. This study utilized structure-from-motion technology with a multi-view three-dimensional (3D) phenotyping platform to investigate architectural plasticity across different maize varieties and planting densities. Seven novel 3D architectural parameters were developed, and 3D canopy models were constructed for light distribution simulation. At V9 stage, medium planting density (67,500 plants ha⁻¹, MD) increased plant side width and convex hull volume by 7.2 and 11.4%, respectively, compared to low planting density (37,500 plants ha⁻¹, LD). High planting density (97,500 plants ha⁻¹, HD) increased by 4.2 and 17.8% compared with MD. Similar changes were maintained at V13 stage. At silking stage, number of voxel volume plant (NVP) and projected area (PJA) decreased by 6.2 and 11.9% (LD to MD), and 4.9 and 3.6% (MD to HD). Under different densities, MC812 and JNK728 showed 17.2-20.0% and 6.2-7.6% decrease in PJA, and 20.0-26.5% and 15.4-21.1% decrease in NVP compared to ZD958. A bottom light transmittance estimation model combining point cloud parameters with support vector regression achieved reliable prediction ( R ²=0.76, RMSE=2.89%). The 3D canopy model effectively simulated population light distribution ( R ²=0.83, RMSE=8.53%). NVP and PJA were identified as critical parameters affecting bottom canopy light transmittance, suggesting their potential as 3D selection indices for maize density tolerance breeding. These findings provide insights into stage-specific architectural plasticity and light interception, supporting molecular design breeding of density-tolerant maize.