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Theoretical and Empirical Relationships Between Oat Test Weight and Groat Proportion

¹USDA-ARS Hard Red Spring and Durum Wheat Quality Laboratory, Harris Hall, North Dakota State University, Dept. 7640, P.O. Box 6050, Fargo, ND 58108. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 701-231-8069. E-mail: douglas.doehlert@ndsu.edu ³Dept. of Plant Sciences, North Dakota State University, Dept. 7640, P.O. Box 6050, Fargo, ND 58108. ⁴NDSU Williston Research Extension Center, 14120 Highway 2, Williston, ND 58801.

Test weight and groat proportion are two very important quality characteristics of oat grain. In this study, we pose the hypothesis that these two characteristics are related through characteristics of grain density. Test weight is defined as the product of kernel density and packing proportion. Groat proportion, in theory, is the ratio of the groat mass to the kernel mass. We present two theoretical constructions expressing test weight in terms of groat proportion, packing proportion and kernel density components. To test these, we have applied measurements of test weight, groat proportion, kernel density components, and packing proportion of 18 oat cultivars grown at six environments. Whereas the groat proportion alone accounted for only 34% of the variation in test weight, our theoretical constructions that included groat proportion could account for ≤82% of variation in test weight. Also, we present previously undescribed variation in oat kernel density components across genotypes and environments. Although the kernel density alone could account for most of the variation in test weight across genotypes, packing proportion appeared to be more important in describing variation in test weight of a genotype across different environments. We observed significant variation in both groat and hull density which, together with groat proportion, described most of the variation in kernel density.