Heat oven to 350°F. In large bowl, combine oats, 1-1/4 cups flour, sugar and margarine; mix until crumbly. Reserve 1 cup oat mixture for topping. Press remaining oat mixture evenly onto bottom of ungreased 8 or 9-inch square baking pan. Bake 13 to 15 minutes or until light golden brown. Cool slightly on wire rack. In medium bowl, combine blueberries, preserves, 1 teaspoon flour and lemon peel, if desired; mix gently. Spread evenly over crust to within 1/2 inch of edges. Sprinkle with reserved oat mixture, patting gently. Bake 20 to 22 minutes or until light golden brown. Cool completely in pan on wire rack. Cut into bars. Store tightly covered.