agridat (version 1.12)

gomez.rice.uniformity: Rice uniformity yield test

Description

An area 20 meters by 38 meters was planted to rice variety IR8. At harvest, a 1-meter border was removed around the field and discarded. Each square meter (1 meter by 1 meter) was harvested and weighed.

Format

A data frame with 648 observations on the following 3 variables.

yield

Grain yield in g/m^2

x

Column position

y

Row position

Examples

# NOT RUN {
data(gomez.rice.uniformity)
dat <- gomez.rice.uniformity

# Raw data plot
require(lattice)
desplot(yield ~ x*y, data=dat, aspect=38/20, main="gomez.rice.uniformity")

# 3x3 moving average.  Gomez figure 12.1
require(reshape2)
dmat <- melt(dat, id.var=c('x','y'))
dmat <- acast(dmat, y~x)
m0 <- dmat
cx <- 2:17
rx <- 2:35
dmat3 <- (m0[rx+1,cx+1]+m0[rx+1,cx]+m0[rx+1,cx-1]+
          m0[rx,cx+1]+m0[rx,cx]+m0[rx,cx-1]+
          m0[rx-1,cx+1]+m0[rx-1,cx]+m0[rx-1,cx-1])/9
dat3 <- melt(dmat3)
desplot(value~Var2*Var1, dat3, aspect=38/20,
        at=c(576,637,695,753,811,870,927),
        main="gomez.rice.uniformity smoothed")

if(require("agricolae")){

  # Gomez table 12.4
  tab <- index.smith(dmat, col="red")$uniformity
  tab <- data.frame(tab)

  # Gomez figure 12.2
  op <- par(mar=c(5,4,4,4)+.1)
  m1 <- nls(Vx ~ 9041/Size^b, data=tab, start=list(b=1))
  plot(Vx ~ Size, tab, xlab="Plot size, m^2")
  lines(fitted(m1) ~ tab$Size, col='red')
  axis(4, at=tab$Vx, labels=tab$CV)
  mtext("CV", 4, line=2)
  par(op)
}

# }