Multi-environment trial of maize in Louisianna at 4 locs in 3 years

Maize yields at 4 locs in 3 years in Louisianna.

Usage

data("kang.maize")

Format

gen: genotype, 17 levels
env: environment, 12 levels
yield: yield, tonnes/ha
environment: environment, 13 levels
year: year, 85-87
loc: location, 4 levels

Details

Yield trials were conducted at four locations (Alexandria, Baton Rouge, Bossier City, and St. Joseph) in Louisiana during 1985 to 1987. Each loc was planted as RCB design with 4 reps. Mean yields are given in this data.

Used with permission of Dan Gorman.

Source

Kang, MS and Gorman, DP. (1989). Genotype x environment interaction in maize. Agronomy Journal, 81, 662-664. Table 2.

Examples

if (FALSE) { # \dontrun{

library(agridat)
data(kang.maize)
dat <- kang.maize

# Sweep out loc means, then show interaction plot.
libs(reshape2)
mat <- acast(dat, gen~env, value.var='yield')
mat <- sweep(mat, 2, colMeans(mat))
dat2 <- melt(mat)
names(dat2) <- c('gen','env','yield')
libs(lattice)
xyplot(yield~env|gen, data=dat2, type='l', group=gen,
       panel=function(x,y,...){
         panel.abline(h=0,col="gray70")
         panel.xyplot(x,y,...)
       },
       ylab="Environment-centered yield",
       main="kang.maize - maize hybrid yields", scales=list(x=list(rot=90)))


# Weather covariates for each environment.
covs <- data.frame(env=c("AL85","AL86","AL87", "BR85","BR86","BR87",
                     "BC85","BC86","BC87", "SJ85","SJ86","SJ87"),
                   maxt=c(30.7,30.2,29.7,31.5,29.4,28.5, 31.9, 30.4,31.7, 32,29.6,28.9),
                   mint=c(18.7,19.3,18.5, 19.7,18,17.2, 19.1,20.4,20.3, 20.4,19.1,17.5),
                   rain=c(.2,.34,.22, .28,.36,.61, .2,.43,.2, .36,.41,.22),
                   humid=c(82.8,91.1,85.4, 88.1,90.9,88.6, 95.4,90.4,86.7, 95.6,89.5,85))

} # }