Preheat oven to 350F.
In a medium mixing bowl, combine flour, baking soda, baking powder, salt.
In a separate bowl, combine sugar, zucchini, oil, egg, lemon juice and zest.
Add dry ingredients to wet, and stir just until combined. Pour batter into greased loaf pan.
Bake for 50-55 minutes, or until golden brown. Remove from oven and cool completely.
Combine glaze ingredients and drizzle over bread. Sprinkle with extra zest.