A team of researchers has found that soybean crop yields increase when the plants have less leaves. As more atmospheric carbon enters the atmosphere, plants are growing more leaves. The research team found that this decreased photosynthesis and other important processes. The details are in a paper that was just published in the journal Global Change Biology.
As carbon dioxide levels continue to rise, plants are producing an excess of leaves. This overall increase in leaf area seems like a good thing but it may actually result in less productivity. There hadn’t been much research done in this area. Scientists were unsure how crop yields would change with the increase of atmospheric carbon.
Researchers from the Institute for Genomic Biology at the University of Illinois studied the effects of extra leaf area on soybean (Glycine max) crop productivity. The team developed a complex computer model to study the possible changes in yields from increased leaf area. They found that the extra leaves were actually detrimental because the plant had to use so many resources to support these new leaves. The extra leaves also meant less photosynthetic efficiency and increased respiration. All of these factors made the plants produce fewer soybeans at harvest. By manually removing the extra leaves, the team saw an increase in productivity of 8-10% for most of the plants. This was accomplished by only removing a small amount of leaf area, about 5%. This would be a very simple way to boost soybean crop yields.
Soybeans are an economically and nutritionally important food crop. Any methods that could increase yields are worth investigating since soybeans can feed so many people while providing high levels of protein. A significant boost in crop productivity, such as from reducing leaf mass, has the potential to reduce global food shortages. The team is now investigating other ways to improve photosynthetic efficiency, including changing leaf locations and angles.
Srinivasan V, Kumar P, Long SP. Decreasing, not increasing, leaf area will raise crop yields under global atmospheric change. Global Change Biology (2016).