Interrelationships among Seed Quality Attributes in Soybean

Soybean [Glycine max (L.) Merr.] meal is used primarily as a livestock feed. The high protein concentration and sulfur‐containing amino acids in the meal contribute to its nutritional value. Oligosaccharides, including raffinose and stachyose in the meal, have detrimental effects on the nutritive value of soy meal as a livestock feed. The objective of this research was to determine the interrelationships among seed protein, oil, oligosaccharides, and S in a breeding population that varied widely in seed protein concentration. Forty‐three random breeding lines that varied in seed protein concentration from 413 to 468 g kg−1 on a dry seed basis, were grown in replicated tests in three environments. Seed yield, protein, oil, oligosaccharides, and S concentrations were determined for entries in each replication in the three environments. Breeding lines and environments varied significantly for each of the traits measured. Concentrations of carbohydrates were not associated with seed yield. Protein increased at the expense of oil (b=−1.560), total carbohydrates (b=−0.171), and sucrose (b=−0.151) Sulfur increased with increasing protein (b=0.008), but S/N ratios were constant across protein concentrations. Decreases in carbohydrates with increases in protein would contribute to increased nutritional value of the meal from these breeding lines. The consistent S/N ratio across the range of seed protein concentrations indicates that S‐containing amino acids were not sacrificed with increases in seed protein.