In 3 1/2- to 6-quart slow cooker, place turkey. In small bowl, mix corn, tomato sauce, 2 tablespoons flour, 1 teaspoon of the salt, chili powder and pepper. Pour over turkey.
Cover; cook on Low heat setting 8 to 10 hours.
About 50 minutes before serving, in medium bowl, mix dumpling ingredients. Drop dough by spoonfuls onto hot turkey mixture. Arrange zucchini slices around dumplings; sprinkle with remaining 1/4 teaspoon salt. Increase heat setting to High. Cover; cook 35 to 45 minutes longer or until toothpick inserted in center of dumplings comes out clean.