dados<-data.frame(Trat=gl(3,10),Y=rnorm(30,10,2))
dados
boxplot(Y~Trat,dados,subset=Trat==1,col = "yellow",ylim=c(0,15))
boxplot(Y~Trat,dados,subset=Trat==2,col = "pink",add = TRUE)
boxplot(Y~Trat,dados,subset=Trat==3,col = "magenta",add = TRUE)
legend(2, 5, c("Trat 1", "Trat 2","Trat 3"),fill = c("yellow", "pink", "magenta"))