Carrot Seed Yield as Affected by Nitrogen Rates at Side-dress

Central Oregon produces approximately 85% of the hybrid carrot seed in the US. Hybrid carrot seed produced in this area supplies seed for the domestic fresh market as well as exporting seed to Europe and Japan. Hybrid European Nantes type carrots have become popular with consumers yet unpopular with seed growers due to unreliable seed yields. Therefore, in an effort to identify what factors could be influencing seed yield in European Nantes type carrots, an N rate field trial was conducted to access the impact of N rate on carrot seed yield.

Methods:

• Nitrogen rates: 0 lb N/a, 40 lb N/a, 75 lb N/a, and 110 lb N/a. Nitrogen was applied as Urea (46-0-0) in a furrow next to the carrot plants in two separate fields.
• Aboveground and below biomass samples were collected every two weeks from emergence until senescence, weighed and analyzed for both macro- and micro-nutrient uptake.
• Soil samples from 0 to 15 cm were collected from each plot each month from fertilization until harvest, including samples collected post-harvest. Samples were analyzed for NO3 and NH4 with a flow injection analyzer.
• Seed was harvested with commercial combines after swathing and cleaned at Central Oregon Seeds, Inc.

Results:
In field 017, seed yield did not correlate with N rates. In field 101, seed yield decreased as N rate increased (Figures 1 and 2).

This is one year of research and further research is needed to more fully assess nutrient uptake in carrot plant growth and effects on seed production.