If thighs are attached, cut away from the legs with sharp knife. Rub turkey pieces with the half lemon. Mix 1 teaspoon of the salt with the pepper, garlic powder, and thyme; rub over surface of turkey pieces.
In a heavy skillet, melt butter over medium-low heat. Sauté onion in hot butter until tender, about 5 minutes. Stir in the carrot pieces, celery, potato, and remaining 1/4 teaspoon of salt, coating with the butter and onion mixture.
Spread the vegetables evenly in a greased or sprayed 13x9x2-inch baking pan. Top with turkey pieces in a single layer. Heat wine in a saucepan just to the boiling point; pour over turkey. Bake, uncovered, at 400° for 1 1/2 hours, or until turkey pieces are tender and juices run clear when pierced with a fork. If turkey is becoming too browned, cover with foil.