|Stevens, William - Bart|
Submitted to: Journal of Sugarbeet Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2008
Publication Date: 6/5/2009
Citation: Stevens, W.B., Violette, R., Skalsky, S., Mesbah, A.O. 2009. Response of Eight Sugarbeet Varieties to Increasing Nitrogen Application: 1. Root, Sucrose, and Top Yield. Journal of Sugarbeet Research. 45:65-83.
Interpretive Summary: Sugarbeet has historically been an important crop in some areas because of its capacity to provide both cash income from the harvested sucrose and livestock feed in the form of above-ground biomass (tops) and root processing byproducts such as pulp and molasses. If sugarbeet varieties respond differently to the amount of available N, both farmers who specialize in sucrose production and those with integrated livestock-sugarbeet systems may be better able to optimize production through variety selection. Available information presents an inconsistent picture regarding the variability in N response among sugarbeet varieties and little information is reported on the interaction of N application and variety on top production or ratio of sucrose to top production. Our objective was to determine if there is justification to vary N fertilizer management depending on which commercial variety is grown. Results generally support prior research on the topic in concluding that the amount of N fertilizer need not be varied for different sugarbeet varieties; however, the significant interaction we observed in sucrose:TDM ratio suggests that there may be small differences in N response among varieties based on how they partition photosynthate between roots and tops, especially at low levels of available N. Further research on this topic may be justified, especially in light of recent dramatic increases in the cost of N fertilizer and a recent transition from conventional sugarbeet varieties to genetically modified herbicide-resistant varieties.
Technical Abstract: Nitrogen management affects both the root and top biomass production of sugarbeet (Beta vulgaris L.). An interaction between genetic factors and the amount of N applied may influence variety selection for different N management and cropping systems practices. A three-year field study was conducted with the objective of comparing the relationship between applied N and root, sucrose and top yield for selected commercial sugarbeet varieties. Eight varieties were treated with five amounts of N (0, 90, 179, 269, and 358 kg N ha-1) at a furrow-irrigated site in northwest Wyoming. Variety affected sucrose concentration and sugar loss to molasses (SLM) in all three years, root yield and sucrose yield in one of three years, and top dry matter (TDM) yield and sucrose:TDM ratio in two of three years. All yield parameters were affected by the amount of N applied (N) in all three years. The variety × N interaction was significant for only the sucrose:TDM ratio in two of three years and was most prominent with 0 or 90 kg ha-1 applied N at which two varieties produced higher amounts of sucrose per unit TDM than the other six varieties. Results do not suggest that N fertilizer management should be variety-specific, but the significant interaction in sucrose:TDM ratio indicates that there may be differences in N response among varieties based on how they partition photosynthate between roots and tops, especially at low levels of available. These differences can help determine which varieties are best suited for different management objectives.