Impact of NPK fertilization on the metabolomic profile and nutritional quality of Portulaca oleracea L. using nuclear magnetic resonance analysis.

Abstract

Purslane is a plant with high nutritional content that is mainly produced in the central part of Mexico. The nutritional content of purslane depends on various factors such as climatic and soil conditions, phenology, and fertilization. This article describes the ¹H NMR metabolomics profiling of purslane in relation to fertilization at two harvest stages: C₁ and C₂ (27 and 42 days after emergence). During the first stage, 30 metabolites were identified including free amino acids and organic acids. In the second stage, 35 metabolites were identified, with higher concentrations of carbohydrates and nucleosides being observed. Multivariate analysis revealed differences in the metabolome between harvests C₁ and C₂. Notably, higher abundances of fructose, galactose, α-glucose, β-glucose, myo-inositol, sucrose, and nucleosides such as adenosine and uridine were observed in C₂. Discriminant analysis further demonstrated variations in metabolites among plants treated with different doses of nitrogen, phosphorus, and potassium at the two harvest stages studied. Plants treated with the highest dose of nitrogen (300 kg N ha^-1) exhibited maximum levels of metabolites, while low nitrogen-treated plants (0 kg N ha^-1) displayed an inverse trend. Amino acids such as alanine, asparagine, GABA, glutamine, histidine, isoleucine, leucine, phenylalanine, proline, threonine, tyrosine, and valine were found to be the most abundant in plants treated with N₃₀₀. In contrast, untreated plants showed higher levels of citric acid and malic acid. Our results highlight the effectiveness of ¹H NMR as a methodology for understanding the role of fertilization and nutrient content in optimizing the crop production of purslane.