Multi-environment trial of wheat, 22 varieties at 14 sites in Australia

Wheat yields of 22 varieties at 14 sites in Australia

data("fox.wheat")

Format

A data frame with 308 observations on the following 4 variables.

gen

genotype/variety factor, 22 levels

site

site factor, 14 levels

yield

yield, tonnes/ha

state

state in Australia

Details

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.

Source

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.

Examples

library(agridat)

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)
#> 64-WO-2-22 64-WO-2-29    8/20/09      Eagle    Gamenya    Halberd      Heron 
#>   2.046429   2.298571   2.466429   2.053571   1.767857   2.043571   1.861429 
#>     JL-157      KL-21    MM/68/1   MMC/21/9      Oxley   Pinnacle     QX-333 
#>   2.167143   2.195000   2.204286   2.338571   2.394286   1.919286   1.822143 
#>    RAC-185    RAC-255     RAC-88    Songlen     Timson     WW-11B      WW-15 
#>   2.349286   2.141429   2.299286   1.952143   1.645000   2.172143   2.425000 
#>    WW-97-2 
#>   2.077143 

# 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)
#> siteLongerenong:genm    siteWaggaMay:genm siteTurretfield:genm 
#>                 2.67                 2.41                 2.18 
#>      siteUrania:genm   siteWaggaJune:genm    siteNarrabri:genm 
#>                 1.80                 1.50                 0.72 
#>    siteNarrogin:genm     siteWarwick:genm siteWonganHills:genm 
#>                 0.68                 0.65                 0.46 
#>     siteNangari:genm     siteWalpeup:genm     siteTheGums:genm 
#>                 0.36                 0.31                 0.15 
#>   sitePirrinuan:genm    siteMerredin:genm 
#>                 0.10                 0.00 

# Figure 1 of Fox
libs(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")