Marihus Altoé Baldotto

Adventitious rooting in cuttings of croton and hibiscus in response to indolbutyric acid and humic acid

Adventitious rooting of ornamental plants can be accelerated by the application of growth regulators, such as auxin. Humic acids, organic matter in soil and organic compounds also have a biostimulant effect. This work evaluated the rooting in cuttings of croton ( Codianeum variegatum L. Rumph) and hibiscus (Hibiscus rosa-sinensis L) in response to the application of different concentrations of indolbutyric acid (IBA) and humic acid (HA). The experiment was carried out in a greenhouse. Apical stem cuttings were treated with solutions at concentrations of: 0, 250, 500, 1000, 2000 mg L -1 IBA and 0, 10, 20, 30, 40 mmol L -1 HA carbon isolated from vermicomposting. Forty-five days after the applications, the cuttings were removed from the pots containing carbonized rice hull and the following variables were measured: rooting number, length and width of leaves, fresh and dry matter of root and aerial part and root area. The results were subjected to analysis of variance and the qualitative and quantitative effects of the treatments were compared by contrast and regression, respectively. Regression equations were used to determine the maximum efficiency level of root dry matter according to IBA and HA. Higher accumulation of root dry matter was recorded for the treatments with the doses 579 mg L -1 IBA and 14 mmol L -1 HA and 970 mg L -1 IBA and 50 mmol L -1 HA for root cuttings of croton and hibiscus, respectively. It was found that the application of eiher IBA or HA at the indicated doses accelerates rooting in cuttings of croton and hibiscus and contributes to the formation of vigorous plants.

Root growth of Arabidopsis thaliana (L.) Heynh. treated with humic acids isolated from typical soils of Rio de Janeiro state, Brazil

As substâncias humicas isoladas da materia orgânica do solo tem sido usadas como estimuladores do metabolismo vegetal. As plantas de Arabidopsis thaliana (L.) Heynh. com apenas cinco cromossomos, ciclo curto e tamanho reduzido, aparecem como modelo para avaliar os efeitos fisiologicos dessas substâncias, as quais sao qualitativa e quantivamente influenciadas pela morfogenese, mineralogia e quimica dos solos. Avaliar os efeitos dessas ambiencias na bioatividade de acidos humicos foi o objetivo principal do presente trabalho. Para isso, foram amostrados os horizontes A e B de quatro solos tipicos da Regiao Norte Fluminense. Apos o isolamento e purificacao, acidos humicos foram usados em concentracoes crescentes nas plantas. O numero e comprimento de raizes laterais e o comprimento da raiz principal foram avaliados e, posteriormente, determinadas as concentracoes de maxima estimulacao, obtidas por meio das curvas de dose resposta e das equacoes de regressao ajustadas. Os resultados mostraram que acidos humicos mais estaveis, isolados de solos em estadio de intemperismo menos avancado, com argila de alta atividade e alta saturacao por bases resultaram em melhores estimulantes fisiologicos das plantas de Arabidopsis.

Gladiolus development in response to bulb treatment with different concentrations of humic acids

Gladiolus is an ornamental species produced for cut flowers and propagated by corms. The early flowering and increase in the number of flower buds, besides the production of commercial corms are constant challenges to be addressed in the crop improvement. Commercial production of ornamentals is technologically accelerated by means of growth regulators. Among them, the auxins stand out for their key role in the adventitious rooting and cell elongation. Alternatively, the humic substances present in the organic matter also have biostimulating effect, which is very similar to the auxinic effect. Therefore, this work aimed to study the growth and development of gladiolus in response to application of different concentrations of humic acids (HA) isolated from vermicompost. Corms were soaked for 24 hours in solutions containing 0, 10, 20, 30 and 40 mmol L-1 of C from HA. The corms were planted in 10-dm3 plastic bags filled with substrate and kept in a greenhouse. Growth of shoots and roots was evaluated. The results showed that the use of HA accelerates growth, and anticipates and increases flowering of Gladiolus.

Aclimatização de orquídea (Cymbidium sp.) em resposta à aplicação de ácidos húmicos

The acclimatization of in vitro propagated orchid is a slow process that can be benefited from the use of bio-stimulants, such as humic substances. This study investigated the growth of Cymbidium sp. in response to application of humic acids extracted from organic compounds poultry litter (AHcf) and manure (AHeb) during the acclimatization period. The plants were immersed in solutions of 0, 10, 20, 30 and 40mmol L-1 of C from AHcf and AHeb and acclimatized in a greenhouse. After 150 days, the plants were collected for measurement of variables: number of leaves, plant height, stem diameter, root and shoot fresh weight, root, shoot and total dry matter and root shoot ratio. Data were submitted to analysis of variance, regression analysis and contrast. The results showed increased accumulation of total dry matter of the plants with the application of concentration of 18.75mmol L-1 of C AHcf and 3.77mmol L-1 of C AHeb with increments in the control 21 and 28%, respectively. It is concluded that the use of humic acids at the indicated doses accelerates the growth of plantlets propagated in vitro of Cymbidium sp. favoring the reduction of time required for acclimatization.

CAPACIDADE DE OXIDAÇÃO COMO ÍNDICE DE ESTABILIDADE DA MATÉRIA ORGÂNICA DE SEDIMENTOS DE ACORDO COM GRADIENTE FLUVIAL-ESTUARINO DO RIO PARAÍBA DO SUL

The hummus composition and it redox properties have been used to evaluate the organic matter quality from natural systems. The objectives of this study were the fractionation of the organic matter and the determination of the oxidation capacity of humic acids to evaluate the organic matter quality of sediments from a gradient fluvial-estuarine in the Brazilian Southeast. The carbon/nitrogen and humic acid/fulvic acid relationships of the organic matter and of the oxidation capacity of humic acids were positively correlated and followed the order: estuarine bordered mangroves ≅ fluvial bordered urban center and pasture > estuarine bordered pasture ≅ marine.

Estoque e frações de carbono orgânico e fertilidade de solo sob floresta, agricultura e pecuária

O entendimento dos fenomenos de trocas de carbono entre solo, agua e atmosfera e fundamental para o manejo e a conservacao de ecossistemas naturais e agrarios. Os objetivos deste trabalho foram determinar os estoques de carbono orgânico, as suas fracoes e a fertilidade do solo sob os manejos florestal (mata remanescente), integrando agricultura e florestas (eucalipto e cutieira) e em monoculturas agricola (sob pivo central) e pastoril (braquiaria), na Bacia do Rio Paraopeba, em Florestal-MG, visando a propor indicadores para a avaliacao de manejo e conservacao do solo. As amostras de solo foram coletadas em remanescente de mata nativa (Mata), em area agricola cultivada sob irrigacao de pivo central (Pivo) e em areas de cultivo de Corymbia citriodora (Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson) (Eucalipto), Joannesia princeps Vell. (Cutieira) e Brachiaria decumbens Stapf (Pasto), nas profundidades de 0 a 20 e 20 a 40 cm. Os resultados indicaram que as estimativas dos estoques e de estabilidade do carbono orgânico aumentaram com a fertilidade do solo. Os sistemas florestais, principalmente a Mata, acompanhada pelos sistemas de manejo do solo integrando florestas a pastagem, em comparacao com o cultivo continuo ou a monocultura de pastagem, apresentaram estoques de carbono maiores, mais estaveis e menos soluveis, com formas mais aromaticas e hidrofobicas (maior relacao AH/AF), indicando menor potencial de lixiviacao de carbono para o sistema aquatico adjacente.

Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria

Devido a alta exigencia energetica e demanda por recursos nao renovaveis para a producao de fertilizantes quimicos, somadas, ainda, ao impacto ambiental provocado pelo uso de tais produtos, e importante a intensificacao de pesquisas com insumos agricolas de base biologica. O uso de bacterias endofiticas fixadoras de nitrogenio e solubilizadoras de fosfatos pode disponibilizar esses nutrientes para as plantas a partir do ar e de fontes fosfatadas pouco soluveis, como fosfatos de rochas. O objetivo deste trabalho foi avaliar a nutricao e o crescimento inicial de milho (Zea mays L.) em resposta a inoculacao de bacterias endofiticas fixadoras de nitrogenio e solubilizadoras de fosfato de rocha, em formulacao simples ou mista, aplicadas com vermicomposto. As plantas de milho dos tratamentos contendo bacterias, tanto as diazotroficas quanto as solubilizadoras de fosfato, quando comparadas as do controle, apresentaram maiores teores foliares de nitrogenio e fosforo no milho, acompanhados por caracteristicas de crescimento mais elevadas. A aplicacao de vermicomposto apresentou efeito sinergico quando combinada com as bacterias endofiticas. Dessa forma, a inovacao da combinacao dos fatores estudados pode contribuir para o desenvolvimento inicial do milho.

Organic matter quality and dynamics in tropical soils amended with sugar industry residue

SUMMARY Soil organic matter depletion caused by agricultural management systems have been identified as a critical problem in most tropical soils. The application of organic residues from agro-industrial activities can ameliorate this problem by increasing soil organic matter quality and quantity. Humic substances play an important role in soil conservation but the dynamics of their transformations is still poorly understood. This study evaluated the effect of compost application to two contrasting tropical soils (Inceptisol and Oxisol) for two years. Soil samples were incubated with compost consisting of sugarcane filter cake, a residue from the sugar industry, at 0, 40, 80, and 120 Mg ha-1. Filter cake compost changed the humic matter dynamics in both content and quality, affecting the soil mineralogical composition. It was observed that carbon mineralization was faster in the illitecontaining Inceptisol, whereas humic acids were preserved for a longer period in the Oxisol. In both soils, compost application increased fulvic acid contents, favoring the formation of small hydrophilic molecules. A decrease in fluorescence intensity according to the incubation time was observed in the humic acids extracted from amended soils, revealing important chemical changes in this otherwise stable C pool.

Eletroquímica de solos modais e de sua matéria orgânica em ambientes tropicais

Soil chemistry soils studies the behavior of the mineral fraction of weathered tropical soils, including electrochemistry, development of charges and adsorption phenomenon. Because of the broad spectrum to be covered in the understanding of the behavior of mineral fraction added to the methodological difficulties, the study of complex soil organic fraction was relatively less developed. The current proposal revisits the early works related to the chemistry of tropical soils with the objective to relate them with electrochemical data of soil carbon stocks. The objective of this study was to review aspects of soil electrochemistry, to determine and to relate the points of zero charge by different methods, the potentials of the electric double layer and the electrochemistry of humus of Brazilian modal soils in a typical sequence of weathering, aiming to generate information for their management and conservation. The methods for estimating the point of zero charge of the soils show different results, but with the same trend among soils. There is a predominance of negative charges on both layers of soils. The negative charges of the colloids are significantly associated with the availability of electrons from the humus and both decrease with the weathering stage of the soil.

Frações da matéria orgânica e propriedades redox de substâncias húmicas em sedimentos de oceanos profundos

Previous studies have verified that free radicals such as quinone moieties in organic matter participate in the redox reactions in natural systems. These functional groups were positively correlated with the increase in aromaticity and hydrophobicity of the humic substances. As an alternative to relatively complex and expensive spectroscopic methods, the redox properties of the humic substances, determined by potentiometric titrations, have been used to evaluate organic carbon stability in soil and sediments. The present study aimed to perform organic matter fractionation and isolation of humic substances from deep oceans in different isobaths (750; 1,050; 1,350; 1,650; 1,950 m) to determine their redox properties by iodimetric titrations under an inert atmosphere and specified conditions of pH and ionic strength. Sediment samples were collected to the North and South of platforms of petroleum exploration located in the North of Rio de Janeiro State, Brazil. Fractions of organic carbon and redox properties of humic substances varied with origin and depth of the samples and with position North and South of the petroleum exploration area.