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.

Effects of different nitrogen forms on growth, phenolics, flavonoids and antioxidant activity in amaranth species

“…Pearson correlation indicated a strong negative relationship between plant height and TFC and TPC which is in line with the findings of (Ogembo 2015, Sousa et al 2008) who demonstrated higher levels of total phenolics were accompanied by lower plant growth in Solanum and Brassica species. Phenolics and flavanoids (quarcetin) concentrations increase was observed under inhibited plant growth in Amaranthus hypochondriacus (Onyango et al 2012).…”

Phytochemicals of Brassicaceae in plant protection and human health – Influences of climate, environment and agronomic practice

“…sabellica), broccoli and brussels sprouts (Milder et al, 2005). The glycosylated flavonoids and simple phenolics such as 3-sophoroside-7-glucosides of kaempferol, quercetin and isorhamnetin and hydroxyl-cinnamates reported in the Brassicaceae (Durkeet and Harborne, 1973;Francisco et al, 2009;Jahangir et al, 2009;Podsę dek, 2007;Sousa et al, 2008), are increasingly attributed beneficial health effects such as reduced risk of age-related chronic diseases, like cancers and cardiovascular disease, and advantageous manipulation of gut microbiota (Clifford, 2004;Graf et al, 2005;Lee and Lee, 2006;Terao et al, 2008;Williamson et al, 2000).…”

Effect of Nitrogen Source, Crop Maturity Stage and Storage Conditions on Phenolics and Oxalate Contents in Vegetable Amaranth (Amaranthus hypochondriacus)

“…As the carbon/nutrient balance theory predicts, in terms of a high plant photosynthetic activity relative to the nitrogen supply, the excess of carbon is allocated to phenolics, a nitrogen-free defense substance (Yongke et al, 2005). Recent work by Sousa et al (2008) demonstrated an overall trend of higher total phenolics concentration in organically grown tronchuda cabbage, accompanied by lower plant fresh weight, as compared with conventionally fertilized samples. They suggested that the lack of nutrients, particularly insufficient nitrogen supply as a result of a low mineralization rate under organic production, could have boosted synthesis of phenolic compounds while limiting rapid growth of new leaves.…”