Interesting that this seems to be closer to Germanic languages than what you see in Italian/Spanish. Any particular reason for that?
Apparently it's German-derived: https://en.wiktionary.org/wiki/cartof
Since potatoes are a South American crop, I suspect that they were first brought to Romania by ethnic Germans trading down the Danube.
It seems to come from German "Kartoffel" and this from older Tartuffel or Tartüffel (18th c.), from Italian tartufolo, diminutive of tartufo (“truffle”), from Medieval Latin *territūberum or Latin terrae tūber (“tuber of the earth”).