Inverse Relationship between Oil and Protein
A study was conducted to examine the potential of predicting soybean seed protein based on oil values as determined by NMR. The research group developed a cross between G. max and G. soja to obtain a wide range of compositional values. The protein content of F2 seed ranged from 40.4% to 52.6% on a dry weight basis. Protein-oil regression analysis was used to generate an equation for predicting seed protein based on oil values. The regression equation (Protein=62.3-1.3(% oil)) with a regression coefficient of 0.46. They reported a negative correlation of –0.69 between the two traits. The researchers suggested that selection of high protein plants based on NMR oil measurements could have merit. Comment: This research points out one of the problems in breeding for high protein soybeans. As one increases the protein content of the soybean, the oil levels tend to be lower. What we really need are high-yielding soybeans with the highest levels of total protein plus oil.

Weir, A.D. and co-workers. 2005. Use of NMR for predicting protein concentration in soybeans seeds based on oil measurements. J. Am. Oil Chemists Soc. 82(2): 87-91.