Further, leaves on a single plant differ in the amount of light that they receive. The amount of light incident on a leaf decreases as sunlight passes downward through the canopy. Leaves on the upper part of the canopy tend to shade and reflect light away from the lower leaves. Plants with somewhat vertical leaves (erectophyle plant type) allow more downward passage of light and tolerate high population planting than plants with drooping leaves (planophyle type) (Chapman and Carter 1976). Row planting and proper spacing can also minimize interplant shading.