title: Multivariate analysis of tronchuda cabbage (Brassica oleracea L. var. costata DC) phenolics: influence of fertilizers.
abstract: A field experiment was carried out to investigate the effect of fertilization level on the phenolic composition of tronchuda cabbage ( Brassica oleracea L. var. costata DC) external and internal leaves. Eight different plots were constituted: a control without fertilization, one with organic matter, and six experiments with conventional fertilizers (nitrogen, boron, and sulfur, two levels each). The phenolic compounds were analyzed by reversed-phase HPLC-DAD. External and internal leaves revealed distinct qualitative composition. In the internal leaves were found 15 phenolics (5 kaempferol and 10 cinnamic acid derivatives), whereas the external leaves presented 3- p-coumaroylquinic acid and 13 kaempferol derivatives. Principal component analysis (PCA) was applied to assess the relationships between phenolic compounds, agronomical practices, and harvesting time. Samples obtained with conventional practices were quite effectively separated from organic samples, for both types of leaves. In general, samples developed without any fertilization presented the highest phenolics amounts: external and internal leaves contained 1.4- and 4.6-fold more phenolic compounds than the ones that received conventional fertilizer, respectively, and the internal leaves presented 2.4 times more phenolics than the ones grown with organic amendment. Additionally, samples from organic production exhibited higher total phenolics content than those from conventional practices, collected at the same time. Samples harvested first were revealed to be distinct from the ones collected later. The results show that it is possible to grow tronchuda cabbage without excess fertilizers, with highest amounts of phenolics and reduced environment contamination.
authors.affiliation: REQUIMTE/Serviço de Farmacognosia, Faculdade de Farmácia, Universidade do Porto, R. Aníbal Cunha, 164, 4050-047 Porto, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Sousa
authors.forename: David M
authors.initials: DM
authors.lastname: Pereira
authors.forename: José A
authors.initials: JA
authors.lastname: Pereira
authors.forename: Albino
authors.initials: A
authors.lastname: Bento
authors.forename: M Angelo
authors.initials: MA
authors.lastname: Rodrigues
authors.forename: Sonia
authors.initials: S
authors.lastname: Dopico-García
authors.forename: Patrícia
authors.initials: P
authors.lastname: Valentão
authors.forename: Graciliana
authors.initials: G
authors.lastname: Lopes
authors.forename: Federico
authors.initials: F
authors.lastname: Ferreres
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Seabra
authors.forename: Paula B
authors.initials: PB
authors.lastname: Andrade
mesh_terms: D000383:Agriculture / Q000379:methods; D000704:Analysis of Variance; D001895:Boron / Q000008:administration & dosage; D001937:Brassica / Q000737:chemistry* / Q000254:growth & development*; D002851:Chromatography, High Pressure Liquid; D005308:Fertilizers; D009584:Nitrogen / Q000008:administration & dosage; D010636:Phenols / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D012621:Seasons; D013455:Sulfur / Q000008:administration & dosage
chemical_list: D005308:Fertilizers; D010636:Phenols; D013455:Sulfur; D009584:Nitrogen; D001895:Boron