IN SHORT

''Historically, man has taken his agriculture with him into new frontiers,'' said a seed company executive the other day. That means the frontiers of space, too, as the company packages seeds for black-eyed peas, watermelon, and even marigolds to be tested on the January space shuttle. Does anyone doubt that someday something will be growing in the sands of Mars, to use the phrase in an old science-fiction title, just as in the fields of Kansas? Meanwhile, those black-eyed peas should lend themselves to a variation of the old Phil Harris song, ''That's What I Like About the South, er, Shuttle.''