Abstract:

In order to improve the selection efficiency of vegetable soybean and optimize the quality evaluation system,
eighteen leading cultivars of vegetable soybean in Jiangsu province were tested for their physical indexes (pod length, pod
width, pod thick, hundred pods weight, kernel weight, L*, a*, b*, hardness, and moisture content) and chemical indexes
(VC, chlorophyll, crude fat, starch, soluble sugar, soluble protein, isoflavone, and LOX activity). The results showed
that chlorophyll content, LOX activity, isoflavone content, starch content, kernel weight, hundred-pod weight and a* had
greater coefficients of variation among species, while L* and moisture content had smaller coefficients of variation, and
the remaining parameters were not significant. Principal component analysis showed that eighteen indicators reflecting the
quality of vegetable soybean might be represented by seven principal components (cumulative contribution rate of 92.332 9%).
According to the clustering results, eight quality parameters including kernel weight, chlorophyll, VC, soluble sugar, crude
fat, isoflavone, hardness and a* selected from seven categories of principal components could substitute the original eighteen
indicators so as to simplify the evaluation indicator system. Among eighteen soybean varieties, the comprehensive quality of
Xudou No.17 was the best, closely followed by Qufan No. 2 and Xindali No. 1, while Sudou No. 8 was the worst.

Key words: vegetable soybean, quality trait, principal component analysis, cluster analysis