Contribution of Leaves at Different Canopy Levels to Seed Production of Upright and Lodged Soybeans (Glycine max (L.) Merrill)1

In a 2‐year study at Urbana, Illinois, upright soybeans (Glycine max (L.) Merrill) yielded 10% more than naturally lodged plants. Defoliation treatments applied to the upper, middle and lower third of individual soybean plants growing in natural ecosystems reduced their seed yields by 17, 22 and 4% respectively as compared to nondefoliated plants. Removal of leaves from a particular area of the plant generally decreased seed yields within that area but also affected the yields of other areas of the plant.