Changes in Free Amino Acid and Kjeldahl N Concentrations in Seeds from Vegetable-Type and Grain-Type Soybean Cultivars during the Cropping Season

Abstract

Immature soybean seeds of the vegetable-type (edamame) cultivars that are harvested 30−40 DAF and consumed as a vegetable are preferred by consumers over those of the grain-type cultivars. This study was carried out mainly to examine differences in the concentrations of free amino acids in seeds of the edamame and grain-type cultivars. Asparagine, alanine, and glutamic acid were the major components in immature seeds of the edamame and grain-type cultivars. The concentrations of these amino acids increased until 30−40 DAF and then decreased in seeds of the edamame cultivars, while in seeds of the grain-type cultivars, they decreased continuously starting 20−30 DAF toward mturity. The differences in free amino acid concentrations between immature seeds of the edamame and grain-type cultivars may indicate that these two types of soybean cultivars belong to genetically different ecotypes. Keywords: Glycine max; soybean; edamame; amino acid; water-soluble nitrogen