Response of Several Sugarbeet Cultivars to N Fertilization: Yield and Crown Tissue Production

The level of plant available N greatly affects sugarbeet (Beta vulgaris L.) quality, sucrose production, and the amount of lower quality crown ussue produced. The response of several sugarbeet cultivars to N fertilization was studied in 1977 and 1978 to determine: i) what level of available N was needed by each cultivar to maximize sucrose production; ii) if each cultivar would respond similarly to N fertilization; and iii) if crown tissue production varies with cultivar. Nitrogen rates from 0 to 448 kg/ha were used as main plots with three to five commercially-grown sugarbeet cultivars as subplots in the study. Root and sucrose yield, sucrose content, clear juice purity, and crown tissue production were determined for each treatment. All sugarbeet cultivars tested responded similarly to increasing levels of available N with crown tissue growth increasing linearly, sucrose content and clear juice purity decreasing linearly, and whole root yield increasing curvilinearly. Addition of some N fertilizer was needed to maximize sucrose production; however, as the level of N fertilization increased above the N level needed for maximum sucrose production, sucrose production decreased. Root tissue growth and sucrose production were maximum at the same N level, but maximum sucrose production did not coincide with maximum whole root yield. Sucrose production was maximum at the same N level for all cultivars. Thus, sugarbeet producers need not vary N fertilizer rates for each sugarbeet cultivar grown. However, total amount of sucrose production per unit area and crown growth did vary with cultivar. At optimum N fertilization, crown tissue accounted for 12 to 17% of the whole root yield, depending on year and cultivar grown. Results of this study indicate that N fertilization influences sugarbeet quality, crown tissue production, and level of sucrose production more than does sugarbeet cultivar.