fox.wheat {agridat} | R Documentation

## 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.

### Source

Fox, P.N. and Rathjen, A.J. (1981). Relationships between sites used in the interstate wheat variety trials. Australian Journal of Agricultural Research, 32, 691-702.

Electronic version supplied by Jonathan Godfrey.

### Examples

    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")

[Package agridat version 1.16 Index]