Dry matter content as a key indicator of physiological and quality traits in sugar beet

Dry matter percentage (DM) is a critical physiological trait in sugar beet, functioning not only as a quantitative measure but also as an integrative marker of carbon assimilation, assimilate partitioning, and ionic regulation. We hypothesized that variation in DM across genotypes arises from differences in photosynthetic efficiency, sucrose allocation to storage roots, and mineral ion homeostasis. To test this, we evaluated 66 sugar beet cultivars across 47 field trials (2019–2024) and assessed the relationships between DM and key agronomic, quality, and physicochemical traits. DM ranged from 15.8 to 27.1%, reflecting substantial genotypic diversity together with interannual environmental variation. Spearman’s rank correlation analysis revealed strong positive associations between DM and sucrose content ( r = 0.88), white sugar content ( r = 0.87), and extraction coefficient of sugar ( r = 0.78), whereas moderate positive correlations were observed with sugar yield ( r = 0.34) and white sugar yield ( r = 0.54). Conversely, DM was negatively correlated with root yield ( r = − 0.22), sodium ( r = − 0.75), nitrogen ( r = − 0.31), and molasses sugar ( r = − 0.71). Multivariate regression confirmed that DM significantly improves quality-related traits while reducing impurity-related traits, with no significant influence on potassium or alkalinity. Year-specific correlation analyses further demonstrated that the positive associations of dry matter with sugar content, white sugar content, and extractable sugar coefficient, together with its negative association with sodium concentration, remained consistent across growing seasons, whereas relationships with yield-related traits were more variable. These findings support the role of DM as a mechanistic marker of source-sink dynamics and ion regulation in sugar beet physiology. By linking DM to underlying physiological processes, this study provides a framework for selecting genotypes with enhanced sucrose accumulation and extractable sugar quality. DM thus emerges as a reliable indicator for breeding programs aiming to improve sugar quality and processing efficiency while maintaining acceptable field performance.