Combine rice, apples, lemon juice, 1/4 cup sugar, cinnamon, salt in large bowl. Spoon into buttered shallow 2-quart baking dish.
Mix flour and remaining 1/2 cup sugar. Cut in butter until mixture is crumbly. Stir in nut meats. Sprinkle over rice mixture. Bake at 350 degrees 30 minutes, or until apples are tender. Serve warm topped with whipped cream, if desired.