Changes in Phenolic Profile and Total Phenol and Total Flavonoid Contents of Guadua angustifolia Kunth Plants under Organic and Conventional Fertilization

Abstract

Agronomic management of a crop, including the application of fertilizers and biological inoculants, affects the phenol and flavonoid contents of plants producing these metabolites. Guadua angustifolia Kunth, a woody bamboo widely distributed in the Americas, produces several biologically active phenolic compounds. The aim of this study was to evaluate the effect of chemical and organic fertilizers together with the application of biological inoculants on the composition of phenolic compounds in G. angustifolia plants at the nursery stage. In 8-month-old plants, differences were observed in plant biomass (20.27 ± 7.68 g) and in the content of total phenols and flavonoids (21.89 ± 9.64 mg gallic acid equivalents/plant and 2.13 ± 0.98 mg quercetin equivalents/plant, respectively) when using the chemical fertilizer diammonium phosphate (DAP). No significant differences were found owing to the effect of the inoculants, although the plants with the application of Stenotrophomonas sp. on plants fertilized with DAP presented higher values of the metabolites (24.12 ± 6.72 mg gallic acid equivalents/plant and 2.39 ± 0.77 mg quercetin equivalents/plant). The chromatographic profile of phenolic metabolites is dominated by one glycosylated flavonoid, the concentration of which was favored by the application of the inoculants Azospirillum brasilense, Pseudomonas fluorescens, and Stenotrophomonas sp. In the case study, the combined use of DAP and bacterial inoculants is recommended for the production of G. angustifolia plant material with a high content of promising biologically active flavonoids or phenolics.

Dynamic of Phenolic Compounds in Guadua angustifolia Kunth under Chemical, Organic, and Biological Fertilization

“…Additionally, when reviewing the effects of organic fertilization with humus or conventional fertilization with DAP on the TPC and TFC in G. angustifolia leaves, the absence of significant differences with the control indicates that watering is enough to obtain the same TPC or TFC content. However, these results contrast with the findings reported by [33] for G. angustifolia, where the application of DAP resulted in a considerable increase in phenolic compound content. This is because the biomass of plants fertilized with DAP was greater compared to other treatments, allowing us to obtain a higher content of phenolic compounds per plant, which makes DAP fertilization the preferred option when the interest is the production of plant material with a high content of phenolic compounds [33].…”

“…Secondly, it can alter the resource allocation patterns between primary and secondary metabolism, where the production of polyphenolic compounds decreases if growth increases [82,83]. This is similar to what was reported in eight-month-old greenhouse-propagated G. angustifolia plants, where the application of humus also resulted in a reduction in the content of phenolic compounds, which was accompanied by low foliar N levels [33].…”

“…Azotobacter sp., Azospirillum sp., Bacillus sp., Stenotrophomonas sp., and Pseudomonas sp., were identified to augment the content of phenolic compounds in plants [21,32], especially when combined with other fertilizers. This was recently reported for G. angustifolia [33].…”

“…This inoculant is known to contain indolic derivatives [48], including indole-3-acetic acid (IAA), whose application increases the expression of the genes CHS and CHI, which are part of the metabolic pathways involved in the production of chalcone, a precursor of various flavonoids. It also regulates the expression of the genes FLS and F3'H, which are involved in the synthesis of flavonoids such as quercetin and kaempferol [72], flavonoids that were previously described in the chemical profile of the genus Guadua, including G. angustifolia [8], which was also described to have a rich profile of C-glycoside flavonoids [8,33]. Additionally, it was demonstrated that exogenous auxins, such as those produced and released by microorganisms in different biofertilizers, are capable of inducing the synthesis of jasmonic acid [73,74], which in turn promotes the synthesis of phenolic compounds by increasing the expression of the PAL gene [75].…”

“…The volume of the biofertilizers was 100 mL at a concentration of 5%. The substrate has the following physical and chemical properties: texture is silt loam, pH 6.68, electric conductivity 0.99 dS/m, oxidizable organic carbon 7.49%, organic matter 12.9%, total nitrogen 0.624%, available phosphorus 12.2 mg/kg, iron 2.55 mg/kg, copper 0.19 mg/kg, zinc 5.18 mg/kg, boron 0.612 mg/kg, sulfur 37.6 mg/kg, effective cation exchange capacity 26.3 cmolc/kg, exchangeable potassium 0.35 cmolc/kg, exchangeable calcium 19.33 cmolc/kg, exchangeable magnesium 6.60 cmolc/kg, exchangeable sodium 0.24 cmolc/kg, and apparent density 0.789 g/cm 3 [33].…”