Bonferroni´s correction in a Duncan Test in R

Question

Im doing the same method that is in the image Image, i need to know how can i put the script in R to make the Bonferroni´s correction in the Duncan Test that they mentioned, given "(α´= α/3, α=0.05)". I used the following script:

  library(agricolae)
  model <- aov(value~ind,data=data.frame)
  comparison <- duncan.test(model, "Ind", main= "comparison")
  duncan.test(model,"ind", console=TRUE) 

I tried to correct the p-value adding the "alpha" in the duncan.test following one of your answers Answer from StackOverflow , like this: alpha by 3 = 0.05/3 ~ 0.0167, but it produced an error in the program. I would really appreciate your help.