How to hang IKEA KUNGSFOR kitchen suspension rails, partly in stud, partly in plasterboard
I know you say you are not going to put a row of heavy jars on - but you are probably going to leave that in place when you eventually move out, and the new owner may have different ideas.

For this sort of application I would go for the strongest fixings available - which are a gravity toggle.  Fischer claim theirs have a pull-out strength of 20kg which gives you plenty of margin for error.

This page gives details of the various sorts of plasterboard fixing available, and their ratings. (Note: that is the Fischer site, but other manufacturers have very similar products available.)