Wheat yields of 22 varieties at 14 sites in Australia
A data frame with 308 observations on the following 4 variables.
genotype/variety factor, 22 levels
site factor, 14 levels
state in Australia
The 1975 Interstate Wheat Variety trial in Australia used RCB design with 4 blocks, 22 varieties in 14 sites. Wagga is represented twice, by trials sown in May and June.
The 22 varieties were a highly selected and represent considerable genetic diversity with four different groups. (i) from the University of Sydney: Timson, Songlen, Gamenya. (ii) widely grown on Mallee soils: Heron and Halberd. (iii) late maturing varieties from Victoria: Pinnacle, KL-21, JL-157. (iv) with Mexican parentage: WW-15 and Oxley.
Fox, P.N. and Rathjen, A.J. (1981). Relationships between sites used in the interstate wheat variety trials. Australian Journal of Agricultural Research, 32, 691-702.
Electronic version supplied by Jonathan Godfrey.
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data(fox.wheat) dat <- fox.wheat # Means of varieties. Slight differences from Fox and Rathjen suggest # they had more decimals of precision than shown. tapply(dat$yield, dat$gen, mean) # Calculate genotype means, merge into the data genm <- tapply(dat$yield, dat$gen, mean) dat$genm <- genm[match(dat$gen, names(genm))] # Calculate slopes for each site. Matches Fox, Table 2, Col A. m1 <- lm(yield~site+site:genm, data=dat) sort(round(coef(m1)[15:28],2), dec=TRUE) # Figure 1 of Fox require(lattice) xyplot(yield~genm|state, data=dat, type=c('p','r'), group=site, auto.key=list(columns=4), main="fox.wheat", xlab="Variety mean across all sites", ylab="Variety yield at each site within states")
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