MIDDLEFIELD, Conn. — Through wars, financial panics and a freeze that destroyed its peach crop a century ago, eight generations of the Lyman family have sustained its farm in the hills of central Connecticut. The family behind Lyman Orchards is now looking to cultivate the next generation of owner-operators, concerned that not enough younger members will step up to keep the farm run by the family, as it has been since it was established nearly 275 years ago. “I think it’s a little of ‘to be determined,’ ” said John Lyman, executive vice president of Lyman Orchards.