Root yield and technological quality of sugar beet as affected by harvest time under the conditions of the Western Forest-Steppe of Ukraine

This study evaluated the effects of hybrid, vegetation period duration, weather conditions, and harvest timing on sugar beet (Beta vulgaris L.) yield and technological quality under short-rotation cropping systems in the Western Forest-Steppe of Ukraine. Field experiments were conducted in 2022-2024 on commercial fields using six industrial hybrids and five harvest intervals from late September to mid-November. Root yield, sugar content, sugar yield, α-amino nitrogen, K+ and Na+, invert sugars, and the technological quality index (Iq) were assessed using ANOVA, correlation analysis, and principal component analysis (PCA). Extending vegetation from 185 to 200 days increased root yield by 11-12% and sugar yield by 0.8-1.2 t/ha. The optimal harvest window (10-25 October) provided the highest performance, with root yields of 68-73 t/ha, sugar content of 16.2-16.6%, and sugar yields of 14.6-16.3 t/ha. Early harvest resulted in reduced sugar content and Iq, whereas harvesting after 10 November did not increase yield and caused deterioration of technological quality due to elevated α-amino nitrogen and molasses-forming ions. PCA showed that over 85% of the total variation was explained by technological quality and moisture-related factors. Strube hybrids demonstrated greater stability under extended vegetation compared with KWS hybrids. These results define an optimal harvest window for maximising sugar beet productivity and quality under temperate meteorological conditions.