PS1 - correction

In /etc/profile.local I have PS1 defined as PS1=`echo '\n\h:\033[1m$PWD\033[0m\n# '` <- for root (if UID = 0) PS1=`echo '\n\h:\033[1m$PWD\033[0m\n> '` <- for others How do I change the command line prompt when I "su" as opposed to "su -"? Sorry for the newbie question ...