Abstract
<title>Abstract</title> <p> <bold>Background</bold> Sugar extraction coefficient (ECS) is a key determinant of sugar beet profitability and processing efficiency. However, the relative importance of genetic and management factors controlling ECS under commercial production conditions remains poorly quantified. This study evaluated the contributions of cultivar, planting date, location, and crop growth duration to ECS variation in autumn-sown sugar beet. <bold>Methods</bold> Data were collected from 127 commercial sugar beet fields representing eleven cultivars across production environments in Golestan Province, Iran, during the 2024–2025 growing season. A combination of regression, stability, and yield-gap analyses was used to identify the major determinants of ECS and to define management thresholds associated with improved sugar extraction efficiency. <bold>Results</bold> Significant differences among cultivars were detected, but management-related factors explained a substantially greater proportion of ECS variation than cultivar effects. Piecewise regression identified an optimum planting window between DOY 219 and 238 and indicated that approximately 218 days of crop growth were required to achieve maximum ECS. Yield-gap analysis showed that growth duration accounted for 76.2% of the total management-related ECS gap, whereas planting date contributed 23.8%. Among the evaluated cultivars, Sweet Dam combined high ECS performance with superior stability across environments. <bold>Conclusions</bold> Under commercial production conditions, sugar extraction efficiency was influenced more strongly by management practices than by cultivar differences. Optimizing planting schedules and ensuring adequate crop growth duration offer greater opportunities for improving ECS than cultivar replacement alone. These findings provide a practical basis for enhancing sugar quality and production efficiency in autumn-sown sugar beet systems. </p>