Prepare oven and loaf pan: Preheat oven to 350°F. Coat an 8 ½- x 4 ½-inch loaf pan with baking spray; set aside.
Combine dry ingredients: Whisk together flour, granulated sugar, baking soda, and salt in a large bowl until combined.
Make batter: Whisk together sour cream, oil, eggs, and 2 teaspoons of the lemon zest in a medium bowl until combined. Create a well in center of dry ingredients. Gradually add sour cream mixture to flour mixture, stirring until just combined.
Add blueberries: Fold in 1 cup of the blueberries; transfer batter to prepared pan. Sprinkle top of batter evenly with turbinado sugar and remaining ¼ cup blueberries.
Bake the bread: Bake in preheated oven until a wooden pick inserted in center comes out clean, about 1 hour. Let cool in pan 10 minutes. Carefully loosen edges from side of pan, remove loaf, and cool completely on a wire rack, about 1 hour.
Add drizzle: Whisk together powdered sugar, 2 tablespoons of the lemon juice, and remaining 1 teaspoon zest in a small bowl until smooth and combined, adding more lemon juice, 1 teaspoon at a time, as needed to reach desired consistency. Drizzle over cooled cake.
