Embedded partially replicated designs for grain quality testing

The literature on the design and analysis of cereal variety trials has focussed on the trait of grain yield. Such trials are also used to obtain information on grain quality traits but these are rarely subjected to the same level of statistical rigour. The data are often obtained using composite rather than individual replicate samples. This precludes the use of an efficient statistical analysis. In this paper we propose an approach in which a proportion of varieties is grain quality tested using individual replicate samples. This is achieved by embedding a partially replicated design (for measuring quality traits) within a fully replicated design (for measuring yield). This allows application of efficient mixed model analyses for both grain yield and grain quality traits.