Determination of the Mineral Composition of Watercress and Data Evaluation Using Multivariate Analysis

Abstract

This paper reports the determination of the mineral composition of watercress (Nasturtium officinale Cruciferae, Brassicaceae), grown in soils from three cities in the Bahia State of Brazil, and in a fourth city where plants were grown in a hydroponic system. The sampling was carried out during the summer and winter. Analyses were performed with inductively coupled plasma optical emission spectrometry (ICP OES), and the accuracy was confirmed with a certified reference material of apple leaves.

Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed different mineral compositions of the samples collected in the summer and winter.

Samples collected in the summer had a higher concentration of the nutrients iron, calcium, and magnesium, and the samples collected in the winter had a higher concentration of manganese and copper. The average contents of the samples (expressed as wet weight) were 2.50 and 3.03 mg g⁻¹ for calcium, 0.37 and 0.86 mg g⁻¹ for magnesium, 8.68 and 10.84 µg g⁻¹ for iron, 8.42 and 8.47 µg g⁻¹ for zinc, 0.61 and 0.47 µg g⁻¹ for copper, and 7.78 and 5.03 µg g⁻¹ for manganese for summer and winter, respectively. These results are in agreement with values previously reported in the literature. Samples collected from the hydroponic system in the winter had a lower concentration of all nutrients.

Keywords:

• HCA
• Mineral composition
• Multivariate analysis
• PCA
• Watercress

Acknowledgments

The authors are grateful to PRONEX/FAPESB, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and CAPES for providing grants and fellowships.

Notes

*Average of 3 determinations; W-winter; S-summer; Conceição de Jacuipe (CJ), Feira de Santana (FS), Pirajá (PI) and Lauro de Freitas (LF).