Plant Density and Nitrogen Rate Effects on Sugar Beet Yield and Quality Early in Harvest
- Joseph G. Lauer
The sugar beet (Beta vulgaris L.) industry has adopted an early harvest option that lengthens the processing campaign by 15 to 30 d. Field experiments were conducted near Powell, WY, from 1989 to 1991, to determine whether plant density and N rate should be adjusted for earlier harvests. Main plots were N application rates of 0, 112, 168, 224, 280, and 336 kg N ha−1; split plots were target plant densities of 37 100, 61 800, 86 500, and Lll 200 plants ha−1. Harvests were at regular intervals beginning 13 September and ending 25 October. During the harvest season, root yield increased 8.0 Mg ha−1, sucrose content increased 29 g kg−1, and recoverable sucrose increased 2.44 Mg ha−1. The first 112 kg N ha−1 increased root yield 11.8 Mg ha−1, while the next 56 kg N ha−1 increased root yield 5.2 Mg ha−1. Sucrose content decreased from 164 to 157 g kg−1 as N rate increased from 0 to 336 kg ha−1. The first 168 kg N ha−1 increased recoverable sucrose 2.48 Mg ha−1. Plant density had no effect on root yield. Sucrose content increased 5 g kg−1 as plant density increased from 42 000 to 112 000 plants ha−1. Recoverable sucrose increased from 7.40 Mg ha−1 at 42 700 plants ha−1 to a maximum of 7.79 Mg ha−1 at 88 600 plants ha−1. No consistent harvest date ✕ plant density interactions were observed for yield and quality measurements, suggesting that no adjustments in plant density were needed for earlier harvest dates. A harvest date ✕ N rate interaction for recoverable sucrose implies that N rate should be decreased for earlier harvest dates.
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