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Effect of region on the uncertainty in crop variety trial programs with a reduced number of trials

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Abstract

Results from crop variety trials may vary between geographical regions because of differences in climate and soil types. Results are usually presented at regional level. To evaluate the importance of the regions used in the Swedish variety trial programs, we examined which regions produced similar levels of yield and similar ratios in yield between cultivars; the amount by which variance could be reduced by division into regions or clusters of regions; and the amount of trials per region and year, replicates per trial, and trials per year required in order to fulfill specifications on the precision of results. Yield data from spring barley and winter wheat trials performed during 1997–2006 were studied using cluster analysis and variance component estimation. The objectives were (1) to discuss the effects of regions on precision when the number of trials has decreased; (2) to demonstrate the method; and (3) to report the results obtained. In spring barley, clusters of regions produced different levels of yield, but similar yield ratios between cultivars. In winter wheat, clusters of regions giving different yield ratios were identified. When the option of a single analysis was compared with that of region-wise analysis, the reduction in variance with the former, due to the larger number of trials, outweighed the reduction in variance with the latter due to decreased random interaction between trials and cultivars.

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Acknowledgments

This research was supported by the Swedish Farmers’ Foundation for Agricultural Research (SLF). We thank the anonymous reviewers for suggestions that improved the manuscript.

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Authors and Affiliations

  1. Department of Crop Production Ecology, Swedish University of Agricultural Sciences, P.O. Box 7043, 750 07, Uppsala, Sweden

    Johannes Forkman

  2. Department of Epidemiology and Public Health, University of Miami, Miami, FL, 33136, USA

    Saeid Amiri

  3. Department of Energy and Technology, Swedish University of Agricultural Sciences, P.O. Box 7032, 750 07, Uppsala, Sweden

    Dietrich von Rosen

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  1. Johannes Forkman
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  2. Saeid Amiri
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  3. Dietrich von Rosen
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Correspondence to Johannes Forkman.

Additional information

S. Amiri contributed to this article when employed at the Swedish University of Agricultural Sciences, Department of Energy and Technology.

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Forkman, J., Amiri, S. & von Rosen, D. Effect of region on the uncertainty in crop variety trial programs with a reduced number of trials. Euphytica 186, 489–500 (2012). https://doi.org/10.1007/s10681-012-0646-8

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  • DOI: https://doi.org/10.1007/s10681-012-0646-8

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