Multi-environment trial of rape in Manitoba

Rape seed yields for 5 genotypes, 3 years, 9 locations.

Format

A data frame with 135 observations on the following 4 variables.

gen

genotype

year

year, numeric

loc

location, 9 levels

yield

yield, kg/ha

Details

The yields are the mean of 4 reps.

Note, in table 2 of Brandle, the value of Triton in 1985 at Bagot is shown as 2355, but should be 2555 to match the means reported in the paper.

Source

Brandle, JE and McVetty, PBE. (1988). Genotype x environment interaction and stability analysis of seed yield of oilseed rape grown in Manitoba. Canadian Journal of Plant Science, 68, 381--388.

Used with permission of P. McVetty.

Examples

library(agridat)
data(brandle.rape)
dat <- brandle.rape

libs(lattice)
dotplot(gen~yield|loc, dat, group=year, auto.key=list(columns=3),
        main="brandle.rape, yields per location", ylab="Genotype")

# Matches table 4 of Brandle
# round(tapply(dat$yield, dat$gen, mean),0)

# Brandle reports variance components:
# sigma^2_gl: 9369  gy: 14027 g: 72632 resid: 150000
# Brandle analyzed rep-level data, so the residual variance is different.
# The other components are matched by the following analysis.

libs(lme4)
libs(lucid)
dat$year <- factor(dat$year)
m1 <- lmer(yield ~ year + loc + year:loc + (1|gen) +
             (1|gen:loc) + (1|gen:year), data=dat)
vc(m1)
#>       grp        var1 var2  vcov  sdcor
#>   gen:loc (Intercept) <NA>  9361  96.75
#>  gen:year (Intercept) <NA> 14030 118.4 
#>       gen (Intercept) <NA> 72590 269.4 
#>  Residual        <NA> <NA> 75010 273.9 
##      grp        var1 var2  vcov  sdcor
##  gen:loc (Intercept)   9363  96.76
## gen:year (Intercept)  14030 118.4
##      gen (Intercept)  72630 269.5
## Residual          75010 273.9