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

Maize yields at 4 locs in 3 years in Louisianna.

data("kang.maize")

Format

gen

genotype, 17 levels

env

environment, 12 levels

yield

yield, tonnes/ha

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.

Source

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

Used with permission of Dan Gorman.

Examples

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))