agridat (version 1.23)

mcleod.barley: Multi-environment trial of barley in South Canterbury with yield and yield components

Description

Yield and yield components for barley with different seeding rates.

Format

A data frame with 40 observations on the following 10 variables.

year

year, numeric

site

site factor

rate

rate, numeric

plants

plants per sq meter

tillers

tillers per plant

heads

heads per plant

surviving

percent surviving tillers

grains

grains per head

weight

weight of 1000 grains

yield

yield tons/hectare

Details

Trials were conducted at 5 sites, 3 years in South Canterbury. (not all sites in every year). Values are the average of 6 blocks. In 1974 there was a severe drought. The other years had favorable growing conditions.

References

Maindonald (1992).

Examples

if (FALSE) {

library(agridat)

data(mcleod.barley)
dat <- mcleod.barley

# Table 3 of McLeod.  Across-environment means by planting rate
d1 <- aggregate(cbind(plants, tillers, heads, surviving, grains,
                      weight, yield) ~ rate, dat, FUN=mean)
# Calculate income based on seed cost of $280/ton, grain $140/ton.
d1 <- transform(d1, income=140*yield-280*rate/1000)
signif(d1,3)
##  rate plants tillers heads surviving grains weight yield
##    50 112.12    5.22  4.36     83.95  21.25  46.11  3.97
##    75 162.75    4.04  3.26     80.89  19.95  45.10  4.26
##   100 202.62    3.69  2.73     74.29  19.16  44.66  4.38
##   125 239.00    3.28  2.33     71.86  18.45  43.45  4.41
##   150 293.62    2.90  2.00     69.54  17.94  42.77  4.47

# Even though tillers/plant, heads/plant, surviving tillers,
# grains/head, weight/1000 grains are all decreasing as planting
# rate increases, the total yield is still increasing.
# But, income peaks around seed rate of 100.

libs(lattice)
xyplot(yield +income +surviving +grains +weight +plants +tillers +heads ~ rate,
       data=d1, outer=TRUE, type=c('p','l'),
       scales=list(y=list(relation="free")),
       xlab="Nitrogen rate", ylab="Trait value",
       main="mcleod.barley - nitrogen response curves"  )

}