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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #142202


item Havey, Michael
item Cantwell, Marita
item Jones, Meriel
item Jones, Richard
item Schmidt, Norman
item Uhlig, John
item Watson, J
item Yoo, Kil Sun

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2002
Publication Date: 12/15/2002
Citation: Havey, M.J., Cantwell, M., Jones, M.G., Jones, R.W., Schmidt, N.E., Uhlig, J., Watson, J.F., Yoo, K. 2002. Significant variation exists among laboratories measuring onion bulb quality traits. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Standardization of protocols and confidence in measurements become more important as the popularity of low-pungency onion increases. At present, there are no data on the variation in measurements of enzymatically derived onion pyruvate concentrations using a standard protocol. A group of scientists attending the 1998 National Allium Research Conference agreed to cooperatively measure bulb quality attributes [percent dry weight (%DW), soluble solids content (SSC), and enzymatically derived pyruvate concentration as a measure of pungency] to test the hypothesis that there exists negligible variation among laboratories using current standardized techniques. Onion cultivars were grown in field plots with three replications at locations [three cultivars each at Idaho-Oregon (ID-OR), Texas (TX), and Wisconsin (WI)] where each cultivar was adapted. Bulbs were harvested when mature and at least 12 bulbs from each replication were shipped by overnight express to each of the participating laboratories. The experimental unit was a random sample of 10 bulbs from each replication of each cultivar and was used for determinations of %DW, SSC, and pyruvate concentration. The analyses of variance for %DW, SSC, and pyruvate concentration for the ID-OR, WI, and TX trials revealed low coefficients of variation (approximately 6%), indicating a good experiment. Laboratories represented the largest source of variation for %DW, SSC, and pyruvate concentrations (P = 0.025 to <0.001). Means were significantly different among laboratories for all traits and trials, except for SSC in the Texas trial. The laboratory x cultivar interaction for pyruvate concentrations was significant (P<0.023) in the TX trial, indicating that groups did not consistently measure pyruvate concentrations across cultivars. This study clearly demonstrated that one cannot make recommendations on relative pungencies, as estimated by enzymatically derived pyruvate concentrations, of the same lots of onions measured by different laboratories. Based on these results, the onion research community must identify specific procedures to reduce variation for measurement of onion pungency.