Nitrate content, soluble solids content, and yield of table beet as affected by cultivar, sowing date and nitrogen supply

The objective was to provide results to optimize the production of table beet (Beta vulgaris L.) with respect to yield and quality. Field experiments were carried out over 2 years, where the effects of nitrogen (N) supply, sowing date, and cultivar were tested in a block design with four replications. In addition to yield, soluble solids and nitrate N contents of roots were measured to assess quality. Sowing date was an important factor for determining yield and quality of table beet. Sowing dates later than June at the experimental site are not recommended because they resulted in an increase in nitrate N content in fresh weight of up to 3027 mg.kg(-1) and an average yield loss of 46% compared to sowings in April. Soluble solids content (SSC was only slightly affected by planting date. Nitrogen supply did not affect SSC, but increasing N supply led to a major increase in nitrate N content, especially if combined with late sowing dates. It was concluded for early sowing dates that N supply be determined to achieve the maximum yield. With an early sowing date, nitrate N content in fresh weight at harvest was <563 mg.kg(-1), even with a high N supply of 250 kg.ha(-1). Late sowing dates required a reduced N supply to keep harvest nitrate contents below the 2500 mg.kg(-1) required by the processing industry. Recommendations for optimizing N supply, sowing date,and cultivars for table beet should always take into account strong interactions between these factors.