Soybean plants with fewer leaves yield more.

Soybean plants with fewer leaves yield more according to a recent study published in Global Change Biology. The paper found that soybean plants produce too many leaves, most of which are shaded and inefficient, thereby wasting resources like water, carbon and nitrogen. The Use of computer model simulations, scientists have predicted that modern soybean crops produce more leaves than they need to the detriment of yield -- a problem made worse by rising atmospheric carbon dioxide. They tested their prediction by removing about one third of the emerging leaves on soybeans and found an 8 percent increase in seed yield in replicated trials. They attribute this boost in yield to increased photosynthesis, decreased respiration, and diversion of resources that would have been invested in more leaves than seeds. The reduction in leaves allows more sun light to penetrate through the canopy making the whole plant more productive, and it also reduces crop water demand, according to the project lead Praveen Kumar, Lovell Professor of Civil and Environmental Engineering at the University of Illinois. The model predicted that a 30-40 percent decrease in leaf area would increase yields by 8-10 percent in field trials, they decreased leaf area (by manually cutting off new leaflets) by just 5 percent and still increased yields by 8 percent. The researchers are planning to move a step further with bioengineed plants or search for varieties that naturally have fewer leaves to test these preliminary findings on a larger scale.The smaller the leaf numbers the higher the yield.