lt;- aov(ShootDryMass ~ trt, data=rice); anova(rice.aov)
anova(rice.aov)
pause()

summary.lm(rice.aov)$coef
pause()

rice$trt &lt;- relevel(rice$trt, ref="NH4Cl")
  # Set NH4Cl as the baseline

fac1 &lt;- factor(sapply(strsplit(as.character(rice$trt)," \\+"), function(x)x[1]))
anu843 &lt;- sapply(strsplit(as.character(rice$trt), "\\+"), 
function(x)c("wt","ANU843")[length(x)])
anu843 &lt;- factor(anu843, levels=c("wt", "ANU843"))
attach(rice)
interaction.plot(fac1, anu843, ShootDryMass)
detach(rice)
par(old