Objective To address the problems of low utilization rate of above-ground parts and the shortage of fresh-eating varieties in root mustard (Brassica juncea var. megarrhiza) varieties, this study investigated the nutritional advantages of different root mustard germplasms and their various edible parts, aiming to provide a theoretical basis for their comprehensive application and variety breeding.

Method Taking the local variety 'Yibin Root Mustard' as the control, this study determined the content of soluble sugar, soluble protein, chlorophylls, carotenoids, anthocyanins, ascorbic acid, total phenolics, flavonoid, glucosinolates, as well as antioxidant capacity in leaves and fleshy roots of three root mustard accessions 'Yibin Root Mustard' 'CJJ-7' and 'ZJJ-18'. Principal component analysis, correlation analysis and analysis of variance for genetic effects were also analyzed.

Result The contents of bioactive substances and antioxidant capacity in leaves of the three root mustard accessions were significantly higher than those in fleshy roots. The soluble protein content in leaves was 1.57-2.83 times that in fleshy roots. The contents of total chlorophylls, total carotenoids, ascorbic acid, flavonoid and total phenolics in leaves were 58.33-99.02, 14.06-28.03, 1.39-2.29, 13.79-30.37 and 3.26-4.25 times those in fleshy roots, respectively. The total glucosinolates content in leaves was 1.56-3.84 times that in fleshy roots. 'ZJJ-18' exhibited the highest antioxidant capacity and total glucosinolates content in leaves. The contents of ascorbic acid, flavonoid, total phenolics, total glucosinolates and FRAP value in 'ZJJ-18' leaves were 1.12, 1.26, 1.27, 1.47 and 1.75 times those of 'Yibin Root Mustard' leaves, respectively. Anthocyanins were only detected in leaves of 'ZJJ-18'. The soluble sugar contents in fleshy roots of 'ZJJ-18' and 'CJJ-7' were 1.31 and 1.24 times those of 'Yibin Root Mustard', while the total glucosinolates content in fleshy roots were only 54.92% and 59.55% of 'Yibin Root Mustard', respectively.

Conclusion Leaves of 'ZJJ-18' possess high contents of bioactive substances and strong antioxidant capacity, which could be used for processing pickled vegetables such as salted mustard greens. The fleshy roots of 'ZJJ-18' and 'CJJ-7' have high soluble sugar content and low glucosinolates content, making them suitable as fresh-eating root mustard cultivars.