I think other characters already 'turned on' the agricultural rune device after arrival and have been keeping it up and running — but if you mean, can Regulus understand the magical specifics of the rune: it's a fairly obvious setup, so let's go with 'yes,' and that Regulus' acquaintance with his homeworld runes will help in the endeavour! Let's say it includes radicals for earth, (wo)man, sun/time and growth, among others.