agridat (version 1.16)

fox.wheat: Multi-environment trial of wheat for 22 varieties at 14 sites in Australia

Description

Wheat yields of 22 varieties at 14 sites in Australia

Usage

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.

Examples

# NOT RUN {
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")

# }