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15 Examples 267Table 15.7 Summary of models for the Slate Hall dataREML number ofmodel log-likelihood parameters F-statistic SEDAR1×AR1 -700.32 3 13.04 59.0AR1×AR1 + units -696.82 4 10.22 60.5IB -707.79 4 8.84 62.015.7 Unreplicated early generation variety trial - WheatTo further illustrate the approaches presented in the previous section, we consideran unreplicated field experiment conducted at Tullibigeal situated in southwesternNSW. The trial was an S1 (early stage) wheat variety evaluation trialand consisted of 525 test lines which were randomly assigned to plots in a 67by 10 array. There was a check plot variety every 6 plots within each column.That is the check variety was sown on rows 1,7,13,. . . ,67 of each column. Thisvariety was numbered 526. A further 6 replicated commercially available varieties(numbered 527 to 532) were also randomly assigned to plots with between 3 to5 plots of each. The aim of these trials is to identify and retain the top, say 20%of lines for further testing. Cullis et al. (1989) considered the analysis of earlygeneration variety trials, and presented a one-dimensional spatial analysis whichwas an extension of the approach developed by Gleeson and Cullis (1987). Thetest line effects are assumed random, while the check variety effects are consideredfixed. This may not be sensible or justifiable for most trials and can lead toinconsistent comparisons between check varieties and test lines. Given the largeamount of replication afforded to check varieties there will be very little shrinkageirrespective of the realised heritability.We consider an initial analysis with spatial correlation in one direction and fittingthe variety effects (check, replicated and unreplicated lines) as random. Wepresent three further spatial models for comparison. The ASReml input file isTullibigeal triallinenumyieldweedcolumn 10row 67variety 532 # testlines 1:525, check lines 526:532