Comparative trace elemental profile of GLVs grown under conventional, organic and hydroponic farming systems

Green leafy vegetables (GLVs) are vital components of a healthy diet and contribute substantially to dietary trace element intake. This study evaluated trace element concentrations in GLVs grown under conventional, organic, and hydroponic farming systems (n = 27) and marketed in Jaipur, Rajasthan, India. A total of 12 elements (Ba, Be, B, Co, Li, Mn, Mo, Se, Ag, Ti, V, and Zn) were analyzed using ICP-MS. Kruskal-Wallis H and Mann-Whitney U test were used for inferential statistical analyses depending on vegetable type and farming system. Principal component analysis (PCA) was used to identify principal components representing major sources of variation. Hydroponically grown samples exhibited higher concentrations of key essential trace elements, particularly B (12.36 mg/kg), Mn (14.29 mg/kg), and Zn (13.92 mg/kg), than conventional (4.99, 10.48, and 4.84 mg/kg) and organic samples (2.54, 7.68, and 5.20 mg/kg) respectively. Organic samples generally showed lower trace element levels, with negligible concentrations of Be, Co, Li, Se, and V. Conventional samples displayed intermediate but more variable elemental profiles. The results for Kruskal-Wallis analysis indicated significant differences (p < 0.05) for most elements except Mn and Ti. Pairwise comparisons confirmed significant differences between hydroponic and organic systems for several elements (p < 0.001). PCA revealed clear separation among farming systems. Overall, the findings highlight that farming practices influence the elemental composition of GLVs and are useful for evaluating their nutritional quality.