Effect of Row Spacing and Phosphorus Fertilization on the Productivity and Quality of Sugar Beet (Beta Vulgaris L.) Cultivar HM10 in Deir Ezzor Governorate, Syria

Abstract

A field experiment was conducted at Saalu Research Station, General Commission for Scientific Agricultural Research, Deir Ezzor Governorate, Syria, during the 2025/2026 winter growing season to evaluate the effects of row spacing and phosphorus fertilization on the productivity and technological quality of sugar beet (Beta vulgaris L.) cultivar HM10. Three row spacings (35, 45 and 55 cm) and three phosphorus rates (15, 20 and 25 kg P₂O₅ dunum⁻¹) supplied as triple superphosphate (46% P₂O₅) were evaluated in a split-plot design with three replications. Sowing was carried out on 30 October 2025 and roots were lifted at maturity on 24 June 2026. Mean root weight, root yield, soluble solids (°Brix), sucrose content, juice purity, and theoretical and actual sugar yields were determined. The largest mean root weight (870 g) and highest root yield (79.6 t ha⁻¹) occurred at 55 cm × 25 kg P₂O₅ dunum⁻¹. The 35 cm × 25 kg P₂O₅ dunum⁻¹ combination produced the highest sucrose content (15.9%) and the highest theoretical (12.3 t ha⁻¹) and actual (9.9 t ha⁻¹) sugar yields, while the highest °Brix value (20.6%) occurred at 45 cm × 25 kg P₂O₅ dunum⁻¹ and the highest juice purity (83.5%) at 35 cm × 20 kg P₂O₅ dunum⁻¹. The results indicate that wider rows favored individual root growth and root biomass, whereas narrower rows favored sucrose accumulation and sugar yield per unit area. Under the conditions of the study, the 25 kg P₂O₅ dunum⁻¹ rate gave the strongest overall response, while the preferred row spacing depended on the production objective