Soybean potential as a protein source has been limited in the past in part because as yields go up, protein content goes down. To meet the foodneeds of an increasing world population, world soybean production will need to increase to meet the projected demand for high-quality protein.

Current soybean varieties average around 41% protein and 21% oil in the seed, on a dry matter basis. Some varieties, however, contain as high as 55% protein. Researchers at Virginia State University (VSU) are studying how to increase protein content without sacrificing yield.

"Harvest index is a way to measure biological efficiency, or the ratio between seed production and the total biomass of the plant," explains VSU's Harbans Bhardwaj. "There's a positive relationship between biological efficiency and seed yield. The objective of our research has been to use harvest index as a tool to breed soybeans simultaneously for high yield and high protein. A premise of these efforts was to start with high-protein breeding material and indirectly select for high seed yield by using harvest index as a selection tool."

That premise proved true. High-protein soybeans with high harvest indexes also have the highest yields. The research will be valuable in helping scientists select high-yielding soybeans that are high in protein content.

Argentine scientists have conducted similar studies to test if they could increase oil and protein content of soybeans without sacrificing yield. Their results show they can successfully select lines with good grain yield and high oil content and lines with good yield and high protein content.

(Harbans Bhardwaj, Virginia State University; J.C. Suarez, et al, EEA-INTA, Balcarce, Argentina)