Key Components of Eating Quality and Their Dynamic Accumulation in Vegetable Soybean Varieties [ Glycine max (L.) Merr.

Abstract

The eating quality and seed chemical compositions of 30 vegetable soybean cultivars (lines), as well as their correla- tions were analyzed. At the same time, main quality compositions and their roles for eating quality were investigated by path analysis, while the dynamic accumulation of each component was also studied with three cultivars differing in soluble sugar content. Results showed that the cumulative contribution of sucrose, fructose + glucose, raffinose, stachyose, protein, free amino acid and oil for eating quality was 67.8%. A significant positive correlation was found between eating quality score and sucrose content (0.864 ** ), while a significant negative correlation between eating quality score and protein content (-0.439 * ). The average content of raffinose and stachyose at fresh harvest stage was only 7.4% and 12.4% of that at mature stage respectively, which had much less negative impact on eating quality of vegetable soybean than field grain soybean. The optimum harvest time for fresh pods was at 42 days after flowering and could last for one week with highest sucrose content and lowest raffinose and stachyose contents. Besides, the average content of amino acids was higher and fructose + glucose contents were medium, and protein content was 3% less than that at mature stage. Postponing the harvest time deteriorated eating quality due to decreased content in sucrose and monosaccharide, increased content in fat and protein contents, as well as a dramatic increase in raffinose and stachyose contents.