Optimizing Canopy Architecture Synergizes Yield and Quality: A Comprehensive Evaluation of Sugar Beet Germplasm During the Taproot Expansion Stage

The negative relationship between root yield and sugar content remains an important challenge for sugar beet (Beta vulgaris L.) improvement. Optimizing canopy architecture may provide an effective strategy for identifying germplasm with favorable combinations of productivity and quality. In this study, 216 sugar beet accessions were evaluated under a single planting configuration at the Liangcheng Experimental Station, Inner Mongolia, China. Eleven quantitative traits related to canopy architecture, yield, and quality were measured during the taproot expansion stage. Root yield was negatively correlated with sugar content. By integrating Spearman correlation analysis with Random Forest (RF) regression, five complementary indicators, including canopy width, SPAD, leaf length, plant height, and lower leaf angle, were retained for multi-trait evaluation. Principal Component Analysis and Ward’s hierarchical clustering further classified the accessions into High-Yield, High-Sugar, and Balanced phenotypic typologies with distinct combinations of yield, sugar content, and canopy traits. A performance-adjusted RF-TOPSIS framework was subsequently used to rank the 216 accessions. BV82 achieved the highest relative closeness coefficient, and all top 20 accessions belonged to the High-Yield group. Sensitivity analyses indicated that the overall ranking was generally stable under alternative weighting schemes and moderate perturbations of criterion weights. These results provide candidate canopy traits and germplasm resources for further field validation and sugar beet breeding.