A field experiment to investigate the effect of weed competitors on yield of winter wheat was set up as a RCBD with three blocks of 18 plots. Three weed species were used: chickweed (CW), black-grass (BG) and cleavers (CL). Target weed densities were 0, 40, 80, 160, 320 and 640 plants per m2 for CW and BG, and 0, 3, 6, 12, 24 and 48 plants per m2 for CL. However, the weed densities achieved were lower and differed among species.
Source
Welham, S. J., Gezan, S. A., Clark, S. J., and Mead, A. (2015) Statistical Methods in Biology: Design and analysis of experiments and regression
Examples
library(desplot)
#> Error in library(desplot): there is no package called ‘desplot’
desplot(Irrigation ~ WholePlot + Subplot | Block, data=competition, col=Species, cex=2)
#> Error in desplot(Irrigation ~ WholePlot + Subplot | Block, data = competition, col = Species, cex = 2): could not find function "desplot"
summary(aov(Grain ~ Species*Irrigation + Error(Block/WholePlot/Subplot), data=competition))
#>
#> Error: Block
#> Df Sum Sq Mean Sq F value Pr(>F)
#> Residuals 1 1.429 1.429
#>
#> Error: Block:WholePlot
#> Df Sum Sq Mean Sq
#> Irrigation 1 1.704 1.704
#>
#> Error: Block:WholePlot:Subplot
#> Df Sum Sq Mean Sq
#> Species 1 7.835 7.835
#>
#> Error: Within
#> Df Sum Sq Mean Sq F value Pr(>F)
#> Species 3 79.04 26.347 54.357 4.52e-10 ***
#> Irrigation 1 16.64 16.640 34.331 8.14e-06 ***
#> Species:Irrigation 3 3.55 1.183 2.441 0.0927 .
#> Residuals 21 10.18 0.485
#> ---
#> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1