Manejo indígena, substâncias húmicas e fertilidade de solos antropogênicos.

Foram estudados solos provenientes do manejo indígena pretérito (terra preta de índio) na Amazônia brasileira. As terras pretas da Amazônia com horizonte antrópico (Au), possuem fertilidade natural alta geralmente atribuída ao elevado de conteúdo de carbono orgânico e às propriedades físico-químicas das suas substâncias hímicas. Estudaram-se as relações entre as frações humificadas de solos altamente intemperizadas da bacia Amazônica com e sem horizonte antrópico e as característica de fertilidade dos mesmos. Fracionou-se a matéria orgânica do solo em ácido fúlvicos (AF), ácido húmicos (AH) e humina (H), na camada de 0-20cm em diferentes situações de uso. Verificou-se que a fração humina está diretamente relacionada com a fertilidade dos solos antropogênicos e que o manejo indígena pretérito dos solos proporcionou uma matéria orgânica de alta qualidade e bastante humificada, sendo esta responsável pela elevada fertilidade química destes solos.1 CD-RO

Changes in metabolic profiling of sugarcane leaves induced by endophytic diazotrophic bacteria and humic acids.

Plant growth-promoting bacteria (PGPB) and humic acids (HA) have been used as biostimulants in field conditions. The complete genomic and proteomic transcription of Herbaspirillum seropedicae and Gluconacetobacter diazotrophicus is available but interpreting and utilizing this information in the field to increase crop performance is challenging. The identification and characterization of metabolites that are induced by genomic changes may be used to improve plant responses to inoculation. The objective of this study was to describe changes in sugarcane metabolic profile that occur when HA and PGPB are used as biostimulants. Inoculum was applied to soil containing 45-day old sugarcane stalks. One week after inoculation, the methanolic extracts from leaves were obtained and analyzed by gas chromatography coupled to time-of-flight mass spectrometry; a total of 1,880 compounds were observed and 280 were identified in all samples. The application of HA significantly decreased the concentration of 15 metabolites, which generally included amino acids. HA increased the levels of 40 compounds, and these included metabolites linked to the stress response (shikimic, caffeic, hydroxycinnamic acids, putrescine, behenic acid, quinoline xylulose, galactose, lactose proline, oxyproline and valeric acid) and cellular growth (adenine and adenosine derivatives, ribose, ribonic acid and citric acid). Similarly, PGPB enhanced the level of metabolites identified in HA-treated soils; e.g., 48 metabolites were elevated and included amino acids, nucleic acids, organic acids, and lipids. Co-inoculation (HACPGPB) boosted the level of 110 metabolites with respect to non-inoculated controls; these included amino acids, lipids and nitrogenous compounds. Changes in the metabolic profile induced by HA+PGPB influenced both glucose and pentose pathways and resulted in the accumulation of heptuloses and riboses, which are substrates in the nucleoside biosynthesis and shikimic acid pathways. The mevalonate pathway was also activated, thus increasing phytosterol synthesis. The improvement in cellular metabolism observed with PGPB+HA was compatible with high levels of vitamins. Glucuronate and amino sugars were stimulated in addition to the products and intermediary compounds of tricarboxylic acid metabolism. Lipids and amino acids were the main compounds induced by co-inoculation in addition to antioxidants, stress-related metabolites, and compounds involved in cellular redox. The primary compounds observed in each treatment were identified, and the effect of co-inoculation (HACPGPB) on metabolite levels was discussed

Estudo quimiométrico de características químicas e espectroscópicas de ácidos húmicos extraídos de solos com horizonte A antrópico.

Ácidos húmicos de solos escuros da Amazônia brasileira (Terra Preta do Índio) foram caracterizados utilizando-se espectroscopias de UV-Vis, DRIFT, Fluorescência nos modos de excitação e emissão, EPR, e RMN, análises termogravimétricas, composição elementar, e medidas de acidez (total, carboxílica e fenólica) e os dados obtidos foram avaliados por técnicas de estatística multivariada. A fração ácidos húmicos (AH) foi extraída utilizando-se o método da Sociedade Internacional de Substâncias Húmicas (IHSS). Os AH foram separados em três grupos conforme o uso da terra: Solos antropogênicos sob floresta (SAF), solos antropogênicos sob cultivo (SAC) e solos não antropogênicos sob floresta (SNAF). Os solos do grupo SNAF são representativos dos Latossolos amazônicos e foram coletados em áreas adjacentes aos solos antropogênicos, sendo este o grupo referência para comparação com os grupos SAF e SAC. Análises estatístícas multivariadas (análise fatorial, análise de agrupamento e análise discriminante) foram aplicadas no estudo. A mais relevante caracteristica dos AH dos solos antropogênicos, comparado aos solos não antropogênicos foram sua superior reatividade, estabilidade, e grau de humificação. Os resultados obtidos também mostraram diferenças entre os AH dos grupos SAF e SAC

Soil organic matter and fertility of anthropogenic dark earths (Terra Preta de Índio) in the Brazilian Amazon basin.

Propriedades de fertilidade, carbono total (Ctot) e frações químicas da matéria orgânica (fração ácidos fúlvicos - FA, fração ácidos húmicos - HA e fração humina - HUM) foram comparados entre solos antrópicos (Terra Preta de Índio) e Latossolos sem horizonte A antrópico. Os solos antrópicos apresentaram maior fertilidade (pH: 5,1-5,4; S: 8,93-10,33 cmolc kg-1; CEC: 17,2-17,5 cmolc kg-1; V: 51-59 %; P: 116-291 mg kg-1) e maiores teores de carbono total (44,6-44,7 g kg-1) que os Latossolos (pH: 4,4; S: 2,04 cmolc kg-1; CEC: 9,5 cmolc kg-1; V: 21 %, P: 5 mg kg-1, Ctot: 37,9 g kg-1). Os solos antrópicos também tiveram distribuição diferenciada de C entre as frações das substâncias húmicas (FA, HÁ e HUM), expressa pelas razões HA:FA e EA:HUM (EA = HA + FA), que foram de 2,1-3,0 e 1,06-1,08 para as Terras Pretas de Índio e de 1,2 e 0,72 para Latossolos, respectivamente. Enquanto a capacidade de troca catiônica (CTC) de Latossolos apresentou correlação com a fração FA (r = 0,97), a CTC das Terras Pretas de Índio correlacionou-se com a fração HUM (r = 0,82). Essa correlação entre a fertilidade das Terras Pretas de Índio e a fração mais estável das substâncias húmicas (HUM) tem importantes implicações no desenvolvimento de modelos sustentáveis de manejo da fertilidade de solos em ecossistemas tropicais

Soil organic matter and fertility of anthropogenic dark earths (Terra Preta de Índio) in the Brazilian Amazon basin.

The Brazilian Amazon basin in soil organic matter and fertility of anthropogenic dark earths (Terra Preta de Índio)

Microbulk Micromegas in non-flammable mixtures of argon and neon at high pressure

We report on a systematic characterization of microbulk Micromegas readouts in high-pressure Ar+1%iC4H10 and Ne+2%iC4H10 mixtures. Experimental data on gain, electron transmission and energy resolution are presented for a wide range of drift and amplification voltages and pressures from 1 bar to 10 bar for argon and from 5 bar to 10 bar in neon, in steps of 1 bar. Maximum gains higher than 1.7e3 (1.7e4) in argon (neon) are measured for all pressures, remarkably without the significant decrease with pressure typically observed in other amplification structures. A competitive energy resolution at 22.1 keV, but with a slight degradation with pressure, is observed:from 10.8% at 1 bar to 15.6% FWHM at 10 bar in argon and from 8.3% at 5 bar to 15.0% FWHM at1 10 bar in neon. The experimental setup, procedure and the results will be presented and discussed in detail. The work is motivated by the TREX-DM experiment, that is operating in the Laboratorio Subterr\'aneo de Canfranc with the mentioned mixtures, although the results may be of interest for other applications of time projection chambers at high pressures.Comment: 11 pages, 8 figures, prepared for JINST, minor changes in th text, added a referenc

Fracionamento químico da matéria orgânica e características de ácidos húmicos de solos com horizonte a antrópico da Amazônia (Terra Preta).

O objetivo deste trabalho foi quantificar as substâncias húmicas e estudar as características de estabilidade e reatividade dos ácidos húmicos de solos com horizonte A antrópico (Au) de diversas regiões do Estado do Amazonas e observar o efeito de uso agrícola sobre estas propriedades. Foram determinadas a sua composição elementar, comportamento termogravimétrico e grupamentos funcionais

Humic acids induce the expression of nitrate transporters in passion-fruit seedlings.

The management of organic fertilization in passion fruit has been carried out empirically based on the responses of the crops and the experience of farmers. Knowledge of the physiological responses of plants to organic fertilizers is essential to optimize fertilization programs. The objective of this study was to evaluate the differential expression of genes coding for nitrate transporters as well as plasma membrane H+-ATPase in passion fruit seedlings treated with different organic fertilizers in the presence or not of humic acids. The equivalent of one gram of total nitrogen dissolved in water from cattle manure, castor oil cake and urea were added and the seedlings were treated or not with a suspension of humic acids (2 mmol/L). Differential expression of low and high affinity nitrate transporters (PeNRT2.2 and PeNRT1.1 PeNRT2.2e) and H+-ATPase (PeMha) was performed by qRT-PCR. The use of cattle manure increased the differential expression of the high affinity transporter regarding to the control. The application of humic acids amplified the increase observed in the differential transcription of the high-affinity transporter with manure and urea fertilization, with no effect observed with the use of castor oil cake. Humic acids induced transcription of the gene encoding H+-ATPases in all treatments compared to control. The application of biofertilizer based on humic acids in low concentrations directly on the plant can be used with the objective of optimizing the organic fertilization of passion fruit with cattle manure and urea.Título em Português: Ácidos húmicos induzem a expressão dos transportadores de nitrato em mudas de maracujazeir