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Puçá fruits are native to the Cerrado biome yet little explored, presenting different varieties with distinct fruit peel colors. Although puçá fruits have been known to exhibit a good source of bioactive compounds, the phenolic profile of some varieties remains unknown. Based on this context, our research aimed to evaluate the chemical composition and bioactive compounds and characterize for the first time the phenolic profile in yellow puçá, brown puçá, and black puçá by high-performance liquid chromatography coupled with diode array detection (HPLC–DAD). The three puçá varieties contained considerable quantities of important food constituents, such as high concentrations of vitamin C, carotenoids and phenolic compounds. These fruits are mostly composed of phenolic acids, with p-coumaric acid being the major compound in all varieties, while ellagic acid was detected only in the brown puçá. Moreover, (−)-epicatechin was found only in the yellow puçá. This study is the first to report the identification of the phenolic profile in puçá. Moreover, our data indicate that the three fruit varieties present a promising chemical composition, suggesting that they may serve as potential sources of natural antioxidants. In addition, these findings can contribute to the establishment of puçá as a novel ingredient for formulations with functional claims.

The application of organic residues to the soil can increase soluble organic carbon (SOC) and affect the pH and electrolytic conductivity (EC) of the soil. However, the magnitude of these changes depends on the type of residue and the applied dose. This study aimed to evaluate the effect of increasing C rates contained in organic residue on the pH, EC, water-extractable total carbon (WETC), water-extractable organic carbon (WEOC), and water-extractable inorganic carbon (WEIC) in soil treated with manure (chicken, swine, and quail), sawdust, coffee husk, and sewage sludge. The levels of total C (TC- KH2PO4), organic carbon (OC- KH2PO4), and inorganic C (IC- KH2PO4) extractable by a 0.1 mol L-1 KH2PO4 solution were also quantified in soil under the effect of increasing rates of chicken and quail manures. The following rates of organic residue C were applied to a dystrophic Red Latosol (Oxisol) sample: 0, 2,000, 5,000, 10,000, and 20,000 mg kg-1. The addition of organic residues to the soil increased pH, except in the case of sewage sludge, which acidified the soil. The acidity correction potential of chicken and quail manure was highest, dependent on the manure rate applied; regardless of the dose used, sawdust barely alters the soil pH. At all tested rates, the EC of the soil treated with swine manure, coffee husk, and sawdust remained below 2.0 dS m-1, which is a critical level for salinity-sensitive crops. However, the application of chicken or quail manure and sewage sludge at certain rates increased the EC to values above this threshold level. Highest levels of WETC, WEOC, and WEIC were obtained when chicken and quail manure and coffee husk were applied to the Oxisol. The quantities of SOC extracted by KH2PO4 were higher than the quantities extracted by water, demonstrating the ability of soil to adsorb C into its colloids. A adição de resíduos orgânicos pode aumentar o carbono orgânico solúvel (COS) e alterar o pH e a condutividade elétrolítica (CE) do solo, mas a magnitude dessas variações depende do resíduo e de sua dose aplicada. Objetivou-se avaliar o efeito de doses de carbono pela adição de resíduos orgânicos sobre o pH, a CE, o carbono total extraível por água (CTEA), o carbono orgânico extraível por água (COEA) e o carbono inorgânico extraível por água (CIEA), em solo tratado com estercos (galinha, suíno e codorna), serragem, casca de café e lodo de esgoto. Os teores de C total (CT- KH2PO4), C orgânico (CO- KH2PO4) e C inorgânico (CI- KH2PO4) extraível por solução de KH2PO4 0,1 mol L-1 também foram quantificados em solo sob efeito de doses crescentes de estercos de galinha e de codorna. O solo utilizado foi o Latossolo Vermelho distroférrico (LVdf) e as doses de C-resíduo orgânico constituíram-se de 0, 2.000, 5.000, 10.000 e 20.000 mg kg-1. A adição de resíduos orgânicos ao solo promoveu aumento do pH, exceto no caso do lodo de esgoto, que acidificou o solo. Os estercos de galinha e de codorna apresentaram os maiores potenciais de correção da acidez do solo, cuja magnitude é dependente da dose de esterco aplicada; independentemente da dose utilizada, a serragem pouco altera o pH do solo. A CE do solo tratado com esterco de suíno, casca de café e serragem, em todas as doses avaliadas, manteve-se abaixo de 2,0 dS m-1, nível crítico para culturas sensíveis à salinidade. Entretanto, a aplicação de estercos de galinha e de codorna e de lodo de esgoto, para algumas doses, elevou a CE para valores acima desse nível crítico. Os maiores teores de CTEA, COEA e CIEA foram obtidos quando se adicionaram ao Latossolo os estercos de galinha e de codorna e a casca de café. As quantidades de COS extraídas por KH2PO4 foram maiores que as extraídas por água, evidenciando a capacidade de o solo adsorver C em seus coloides.

Determination of organic acids in soils and organic materials is important due to the important role they play in improving the soil's physical, chemical and microbiological conditions. This study identified and quantified low molecular weight organic acids (LMWOA) in soils (dystroferric Red Latosol, dystrophic Red-Yellow Latosol and Quartzarenic Neosol) and organic materials (cow, pig, chicken, quail and horse manures, sawdust, coconut fiber, pine bark, coffee husks, biochar, organic substrate, sewage sludges 1 and 2, garbage compost, pig slurry compost). The following acids were identified: acetic, citric, D-malic, formic, fumaric, maleic, malonic, oxalic, quinic, shikimic, succinic and tartaric.

Soil solution samplers may have the same working principle, but they differ in relation to chemical and physical characteristics, cost and handling, and these aspects exert influence on the chemical composition of the soil solution obtained. This study was carried out to evaluate, over time, the chemical composition of solutions extracted by Suolo Acqua, with the hydrophilic membrane (HM) as a standard, using soils with contrasting characteristics, and to determine the relationship between electrical conductivity (EC) and concentration of ions and pH of soil solution samples. This study was carried out under laboratory conditions, using three soils samples with different clay and organic matter (OM) contents. Soil solution contents of F−, Cl−, NO−3, Br−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+, were analyzed, as well as inorganic, organic, and total C contents, pH, and EC, in four successive sampling times. Soil solution chemical composition extracted by the Suolo Acqua sampler is similar to that collected by the HM, but the Suolo Acqua extracted more Na+ and soluble organic C than the HM solution. Solution EC, cation and anion concentrations, and soluble C levels are higher in the soil with greater clay and OM contents (Latossolo and Cambissolo in this case). Soil solution composition varied over time, with considerable changes in pH, EC, and nutrient concentrations, especially associated with soil OM. Thus, single and isolated sampling of the soil solution must be avoided, otherwise composition of the soil solution may not be correctly evaluated. Soil solution EC was regulated by pH, as well as the sum of cation and anion concentrations, and the C contents determined in the soil liquid phase.

Os efeitos das substâncias húmicas nas propriedades dos solos são conhecidos, porém poucos são os estudos que avaliam os efeitos desses materiais nas plantas; assim, dependendo da concentração e da natureza química das moléculas húmicas aplicadas, pode haver maior expansão radicular, incremento na absorção de nutrientes e maior crescimento das culturas. Com o objetivo de avaliar os efeitos de concentrações de C-ácido húmico na nutrição e no crescimento de mudas de eucalipto, foi realizado um experimento em solução nutritiva, em casa de vegetação. Os tratamentos constituíram-se de duas fontes de ácidos húmicos (material húmico - MH e ácido húmico p.a. - AH p.a.), sendo cada fonte adicionada na solução nutritiva nas seguintes concentrações de C-ácido húmico: 0, 10, 30 e 150 mg L-1. Outros tratamentos foram também testados, utilizando-se a fonte AH p.a. nas concentrações de 0, 10, 30 e 150 mg L-1 C-ácido húmico, acrescidas de 21 mg L-1 de ácido cítrico e 9 mg L-1 de ácido oxálico. Foram analisados a condutividade eletrolítica na solução nutritiva, diâmetro do caule e altura das plantas, matéria seca de caule, de folhas, da parte aérea, da raiz e total, relação matéria seca de raiz:parte aérea, acúmulo de nutrientes no caule e nas folhas. A altura e o diâmetro de caule diminuíram linearmente com a aplicação de concentrações de C-ácido húmico da fonte AH p.a. A utilização do MH, em baixas concentrações de C-ácido húmico (0,07-4,3 mg L-1), propiciou a máxima produção de matéria seca de raiz, caule, folha e total. O maior acúmulo de alguns nutrientes (principalmente N, P e B) resultou, em alguns tratamentos, em reduzidos incrementos (2,4 a 9,3 %) nas produções de matéria seca de raiz, folha, caule e total; assim, não é aconselhável, em solução nutritiva, a aplicação das fontes de ácidos húmicos utilizadas neste estudo para o cultivo de mudas de eucalipto.