Abstract: Differences in the composition of small molecule metabolites in Brassica napus L. cultivars used as both vegetables and oil crops across different growth stages remain unclear. To address this problem, the present study analyzed B. napus L. cv. Dadi 199 using quantitative 1H nuclear magnetic resonance (1H NMR) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). We identified 27 significantly differential small molecule metabolites, including amino acids, organic acids, and phenolic metabolites, across the seedling, budding (stems and leaves), and flowering stages. Different classes of metabolites exhibited distinct stage- and tissue-specific accumulation patterns. Specifically, secoisolariciresinol was determined as a seedling stage-specific metabolite, while the leaves at the budding stage showed higher amino acid levels, and the flowering stage demonstrated significant accumulation of certain flavonoid and phenolic metabolites. Metabolites closely linked to the growth and development of rapeseed were primarily involved in the phenylalanine, tyrosine, and tryptophan biosynthesis pathways. This study provides foundational data for developing methods to comprehensively assess the nutritional composition and quality of rapeseed at different growth stages.

Key words: Brassica napus L.; growth stages; quantitative 1H nuclear magnetic resonance; high performance liquid chromatography-tandem mass spectrometry; phenolic metabolites