Instituto de Ciências Agrárias - CAF

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Análise de algumas variáveis fisiológicas para avaliação do grau de adaptação de ovinos submetidos ao estresse por calor
(Revista Brasileira de Zootecnia, 2002-08-21) Starling, Josiane Maria Cardoso; Silva, Roberto Gomes da; Cerón-Muñoz, Mario; Barbosa, Geraldo Sérgio Senra Carneiro; Costa, Mateus José Rodrigues Paranhos da
Investigaram-se a temperatura retal, a freqüência respiratória e a taxa de evaporação total de ovinos Corriedale sob três temperaturas ambientes, visando uma melhor compreensão dos mecanismos de termorregulação desses animais. Inicialmente, 21 animais adultos foram alojados em câmara climática à temperatura de 45ºC, e pressão parcial de vapor (PV) variável, registrando-se a freqüência respiratória (FR) e a temperatura retal (TR). Baseando-se na FR e TR, foram selecionados 10 animais, cinco com os valores mais baixos, assumindo-os como mais adaptados ao calor (grupo 1) e cinco com valores mais altos, assumindo-os como menos adaptados (grupo 2). Os animais selecionados foram mantidos em câmara climática, onde mediram-se novamente TR, FR e taxa de evaporacão total (TET), sob 20, 30 e 40ºC de temperatura do ar e PV variável. Não houve diferença estatística entre os grupos classificados, para todas as variáveis medidas. Concluiu-se que a utilização das variáveis fisiológicas TR e FR como parâmetros únicos para a seleção destes animais não é suficiente para avaliar o grau de adaptação a temperaturas elevadas.
Análise multivariada da resistência do solo à penetração sob plantio direto
(Ciência Rural, 2006-07) Newes, Walter Luiz de Castro; Gomide, Reinaldo Lúcio; Mantovani, Evandro Chartuni; Sverzut, Claudio Bianor; Borghi, Elaine; Weirich Neto, Pedro Henrique
Com vistas ao aumento da produção, optou-se, no Brasil, pelo acréscimo de área cultivada e pelo intenso uso da motomecanização, o que acarretou prejuízos aos solos agrícolas. Paralelamente, práticas conservacionistas têm sido adotadas, a exemplo do sistema plantio direto. Em ambos os casos, estudos do estado de compactação do solo se fazem necessários. Prática e controversa, a penetrometria é a metodologia mais utilizada para o dimensionamento desse parâmetro. Assim, realizou-se trabalho em um Latossolo Vermelho sob plantio direto visando a identificar a estratificação vertical da resistência do solo à penetração. Foram amostrados 40 pontos, em malha de 50mx50m. Em cada ponto, analisou-se o comportamento do solo em três posições: na linha de semeadura, entre as linhas de semeadura e entre as linhas de semeadura com tráfego de trator agrícola. Os dados foram obtidos com penetrômetro hidráulico-eletrônico. Para identificação das camadas de solo com resistência à penetração semelhante, utilizou-se técnica de análise multivariada, denominada análise fatorial, com rotação ortogonal. Entre as linhas de semeadura, identificaram-se quatro camadas, sendo que as mais superficiais se mostraram com variância relativa maior. Nas entrelinhas com tráfego de trator e nas linhas de semeadura, locais de ação antrópica, identificaram-se três camadas, sendo as mais profundas as de variância relativa mais elevada.
Growth promotion of pineapple 'vitória' by humic acids and burkholderia spp. during acclimatization
(Revista Brasileira de Ciência do Solo, 2010-08) Baldotto, Lílian Estrela Borges; Baldotto, Marihus Altoé; Canellas, Luciano Pasqualoto; Bressan-Smith, Ricardo; Olivares, Fábio Lopes
In vitro propagation of pineapple produces uniform and disease-free plantlets, but requires a long period of acclimatization before transplanting to the field. Quicker adaptation to the ex vitro environment and growth acceleration of pineapple plantlets are prerequisites for the production of a greater amount of vigorous, well-rooted planting material. The combination of humic acids and endophytic bacteria could be a useful technological approach to reduce the critical period of acclimatization. The aim of this study was to evaluate the initial performance of tissue-cultured pineapple variety Vitória in response to application of humic acids isolated from vermicompost and plant growth-promoting bacteria (Burkholderia spp.) during greenhouse acclimatization. The basal leaf axils were treated with humic acids while roots were immersed in bacterial medium. Humic acids and bacteria application improved shoot growth (14 and 102 %, respectively), compared with the control; the effect of the combined treatment was most pronounced (147 %). Likewise, humic acids increased root growth by 50 %, bacteria by 81 % and the combined treatment by 105 %. Inoculation was found to significantly increase the accumulation of N (115 %), P (112 %) and K (69 %) in pineapple leaves. Pineapple growth was influenced by inoculation with Burkholderia spp., and further improved in combination with humic acids, resulting in higher shoot and root biomass as well as nutrient contents (N 132 %, P 131 %, K 80 %) than in uninoculated plantlets. The stability and increased consistency of the host plant response to bacterization in the presence of humic substances indicate a promising biotechnological tool to improve growth and adaptation of pineapple plantlets to the ex vitro environment.
Structural interaction between GFP-labeled diazotrophic endophytic bacterium Herbaspirillum seropedicae RAM10 and pineapple plantlets ‘Vitória’
(Brazilian Journal of Microbiology, 2010-08-26) Baldotto, Lílian Estrela Borges; Olivares, Fábio Lopes; Smith, Ricardo Bressan
The events involved in the structural interaction between the diazotrophic endophytic bacterium Herbaspirillum seropedicae, strain RAM10, labeled with green fluorescent protein, and pineapple plantlets ‘Vitória’ were evaluated by means of bright-field and fluorescence microscopy, combined with scanning electron microscopy for 28 days after inoculation. After 6 hours of inoculation, H. seropedicae was already adhered to the roots, colonizing mainly root hair surface and bases, followed by epidermal cell wall junctions. Bacteria adherence in the initial periods occurred mainly in the form of solitary cells and small aggregates with pleomorphic cells. Bacteria infection of root tissue occurred through the cavities caused by the disruption of epidermal cells during the emergence of lateral roots and the endophytic establishment by the colonization of intercellular spaces of the cortical parenchyma. Moreover, within 1 day after inoculation the bacteria were colonizing the shoots. In this region, the preferred sites of epiphytic colonization were epidermal cell wall junctions, peltate scutiform trichomes and non-glandular trichomes. Subsequently, the bacteria occupied the outer periclinal walls of epidermal cells and stomata. The penetration into the shoot occurred passively through stoma aperture followed by the endophytic establishment on the substomatal chambers and spread to the intercellular spaces of spongy chlorenchyma. After 21 days of inoculation, bacterial biofilm were seen at the root hair base and on epidermal cell wall surface of root and leaf, also confirming the epiphytic nature of H. seropedicae.
Severidade da ferrugem da soja em função do suprimento de potássio e cálcio em solução nutritiva
(Revista Ceres, 2010-12) Pozza, Adélia Aziz Alexandre; Pinheiro, Jadir Borges Pinheiro; Pozza, Edson Ampélio; Moreira, Alécio de Souza; Alves, Marcelo Carvalho
Entre as estratégias para o controle da ferrugem da soja cita-se a nutrição mineral equilibrada. Objetivou-se, neste trabalho, verificar o efeito do cálcio e do potássio na severidade da ferrugem (Phakopsora pachyrhizi), na fotossíntese potencial e na nutrição de plantas de soja. O delineamento experimental foi em blocos casualizados, com 25 tratamentos, 4 repetições e 2 plantas por repetição. Utilizou-se esquema fatorial 5 x 5, com 5 doses de K (4, 5, 6, 7, 8 mmol L^-1), combinadas com 5 doses de Ca (3, 5, 7, 9, 11 mmol L^-1). As plantas foram inoculadas no estádio V4 e, após nove dias, iniciaram-se avaliações da severidade da ferrugem pelas porcentagens de tecido lesionado, as quais foram transformadas em área abaixo da curva de progresso da doença (AACPS).Também foram avaliados a fotossíntese potencial e o teor de nutrientes na matéria seca de raiz, caule e folhas. O suprimento de Ca reduziu a AACPS em todas as doses de K. O suprimento de K também reduziu a AACPS nas doses 5, 7 e 11 mmol L^-1 de Ca. A menor AACPS foi observada na combinação das doses de 8 e 11 mmol L^-1 de K e Ca, enquanto a maior AACPS foi observada nas doses de 4 e 5 mmol L^-1 de K e Ca. As plantas tratadas com as doses 6 e 5 mmol L^-1 de K e Ca e 5 e 5 mmol L^-1 de K e Ca apresentaram melhor resposta fotossintética. Com o incremento das doses de K na solução, houve aumento dos teores foliares de K e redução linear dos teores foliares de Ca. Com o incremento das doses de Ca em solução nutritiva verificaram-se aumentos nos teores desse elemento e redução linear dos teores de K nas folhas.
Efeito de variáveis ambientais, épocas e métodos de plantio na intensidade da seca da haste (Botrytis cinerea) em Hibiscus sabdariffa
(Summa Phytopathologica, 2011-03-16) Oliveira, Carlos Alberto de; Souza, Paulo Estevão de; Pozza, Edson Ampélio; Pinto, José Eduardo Brasil Pereira; Barretti, Patrícia Baston
O presente estudo objetivou avaliar o efeito da temperatura (15, 20, 25 e 30ºC), do período de molhamento foliar (0, 6, 12 e 24 h), de épocas (setembro, outubro, novembro e dezembro) e métodos de plantio (semeadura direta e transplantio de mudas), na intensidade da seca da haste (Botrytis cinerea) do hibisco (Hibiscus sabdariffa). As variáveis ambientais foram avaliadas em condições controladas com inoculação artificial e as épocas e métodos de plantio foram avaliados em condições de infecção natural em campo. Os dados de frequência de infecção analisados, como área abaixo da curva de progresso da frequência de infecção (AACPF) e comprimento de lesões relacionados às variáveis ambientais, foram submetidos à análise de variância e regressão e, em seguida, plotadas as superfícies de resposta. Os dados de incidência (AACPI) relacionados às épocas e métodos de plantio foram submetidos à análise de variância, utilizando-se o programa estatístico Sisvarâ/UFLA. A interação da temperatura e da duração do período de molhamento foliar influenciou a frequência de infecção e o comprimento de lesões da seca da haste. Houve aumento na frequência de infecção e no comprimento de lesões com o incremento do período de molhamento foliar e redução da temperatura. As lesões apresentaram maior tamanho na temperatura de 15ºC e 24 horas de molhamento foliar. Na ausência de molhamento foliar houve manifestação de sintomas somente a 15ºC. A 30ºC houve dependência de maior período de molhamento foliar para a manifestação de sintomas. Houve interação significativa de métodos e épocas de plantio na incidência da doença. Constatou-se menor incidência da seca da haste em transplantio de mudas comparado à semeadura direta em todas as épocas de plantio. Verificou-se aumento da incidência proporcionado pelo atraso na época de plantio nos dois métodos. Registrou-se uma relação direta entre queda de temperatura e aumento da incidência da seca da haste.
Oxidation capacity as an index of organic matter stability from sediments of the Paraíba do Sul river-estuarine gradient
(Química Nova, 2011-04-01) Baldotto, Marihus Altoé; Canellas, Luciano Pasqualoto; Rosa, Raul Castro Carriello; Range, Thiago Pessanha; Salomão, Marcos Sarmet Moreira de Barros; Rezende, Carlos Eduardo
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.
Initial performance of pineapple and utilization of rock phosphate applied in combination with organic compounds to leaf axils
(Revista Ceres, 2011-06) Baldotto, Marihus Altoé; Giro, Validoro Bazoni; Baldotto, Lílian Estrela Borges; Canellas, Luciano Pasqualoto; Velloso, Carlos Xavier
Rock phosphates have low solubility in water, but good solubility in acid. The use of organic compounds together with these phosphorus sources applied to the basal leaf axils of pineapple can increase the solubility of this phosfate source and increase the P availability to the crop. A greenhouse experiment was conducted using Araxá rock phosphate (10 g) in combination or not with solutions containing increasing concentrations of humic acids (0 to 40 mmol L-1 of carbon), with or without citric acid (0.005 mmol L-1), applied to basal leaf axils of pineapple cv. Pérola. Growth and nutritional characteristics of aerial plant parts were assessed. Growth rates of aerial parts and N, P, K, Ca and Mg contents increased curvilinearly with increasing concentration of carbon in the form of humic acids. Maximum values were found for the concentration of 9.3 mmol L-1 of carbon combined with 0.005 mmol L-1 of citric acid and natural phosphate.
Characterization of the resistance of tomato accessions from the bgh-ufv to the geminivírus tomato yellow spot virus
(Revista Brasileira de Agropecuária Sustentável, 2011-07) Malta, Antonio Wilson de Oliveira; Aguilera, Jorge González; Souza, Milton Pereira Flores Victor de; Nick, Carlos; Xavier, César Augusto Diniz; Silva, Derly Jose Henriques da; Zerbini, Francisco Murilo
The viruses transmitted by whiteflies are among those causing relevant losses in tomato cultivation. Among the measures to control these agents, introducing genes for resistance constitutes the main control measure, together with vector control. The objective of this work was to screen for sources of natural resistance to Tomato yellow spot virus (ToYSV) in S. lycopersicum germplasm from the Banco de Germoplasma de Hortaliças (BGH) of the Universidade Federal de Viçosa (UFV), Minas Gerais, Brazil. The 99 accessions and two susceptible controls were inoculated using biolistics. Inoculated plants were grown under greenhouse conditions. The percentage of plants displaying virus symptoms was evaluated at 10, 20 and 30 days after inoculation (DAI). Virus presence or absence in the inoculated plants was confirmed by hybridization with probes labeled with á-[32P]-dCTP, for each evaluation date. Inoculated plants produced typical disease symptoms showing different behavior on the genotypes in relation to ToYSV. Some of the evaluated genotypes showed higher virus tolerance compared to two susceptible controls, in particular the accessions BGH-2039V and BGH-2041 which showed no symptoms and no viral DNA accumulation in 80% of the inoculated plants at 30 DAI. The results suggest that the selected tomato accesses are good sources of resistance to new tomato cultivars tolerant to ToYSV.
Root growth of Arabidopsis thaliana (L.) Heynh. treated with humic acids isolated from typical soils of Rio de Janeiro State, Brazil
(Revista Ceres, 2011-07-06) Baldotto, Marihus Altoé; Baldotto, Lílian Estrela Borges; Muniz, Rafael Carvalho; Dobbss, Leonardo Barros
Soil characteristics related to the genesis, land use and management are important factors in water dynamics in watersheds. This study evaluated physical, morphological and pedogenetic attributes related to water yield potential in small watersheds in Guarapari, ES, Brazil. The following representative profiles were selected, morphologically described and sampled in area of Atlantic Forest domain: Lithic Udifolists, Oxyaquic Udifluventes, Typic Paleudults, Typic Hapludults, Typic Hapludox, Oxic Dystrudepts and Typic Endoaquents. Samples were collected in the soil profiles for physical analysis. Measurements of field-saturated hydraulic conductivity and soil penetration resistance were perfomed in some profiles, which were under different uses. The Endoaquents of Limão Creek can be considered efficient as temporary water reservoirs. However, the use of artificial drainage tends to reduce this effect. Differential erosion was detected by the sand texture on the surface of the Typic Paleudults due to the low degree of clay flocculation, slope, high resistance to the penetration and low hydraulic conductivity of the Bt horizon, making it necessary to adopt soil management practices to increase the water infiltration. Under pasture, mainly in the cattle trails where the trampling is more intense, there was high resistance to penetration in the superficial layers of the Typic Hapludults. The Typic Hapludox have the greatest potential for water yield in the small watersheds because of its greater extent in the headwaters and their morphological and physical characteristics, which can result in increased aquifer recharge.
Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria
(Revista Ceres, 2012-02-06) Baldotto, Lílian Estrela Borges; Silva, Luiz Gonzaga Jr. Santos; Canellas, Luciano Pasqualoto; Olivares, Fábio Lopes; Baldotto, Marihus Altoé
Due to the high energy requirement and demand for non-renewable resources for the production of chemical fertilizers, added also to the environmental impact caused by the use of such products, it is important to intensify research on bio-based agricultural inputs. The use of nitrogen-fixing endophytic and phosphate solubilizing bacteria can provide these nutrients to the plants from the air and poorly soluble phosphorus sources, such as phosphate rock. The objective of this study was to evaluate the nutrition and initial growth of maize (Zea mays L.) in response to the inoculation of nitrogen-fixing and rock phosphate solubilizing endophytic bacteria, in single or mixed formulation, applied with vermicompost. The treatments containing bacteria, both diazotrophic and phosphate solubilizing, when compared to controls, showed higher levels of leaf nitrogen and phosphorus in maize, as well as higher growth characteristics. The application of vermicompost showed synergistic effect when combined with endophytic bacteria. Thus, the innovation of the combination of the studied factors may contribute to the early development of maize.
Organic matter quality and dynamics in tropical soils amended with sugar industry residue
(Revista Brasileira de Ciência do Solo, 2012-06-18) Busato, Jader Galba; Leão, Tairone Paiva; Baldotto, Marihus Altoé; Canellas, Luciano Pasqualoto
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 illite-containing 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.
Adventitious rooting in cuttings of croton and hibiscus in response to indolbutyric acid and humic acid
(Revista Ceres, 2012-07-05) Baldotto, Lílian Estrela Borges; Baldotto, Marihus Altoé; Soares, Raíssa Rezende; Martinez, Herminia Emilia Prieto; Venegas, Vitor Hugo Alvarez
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.
Groundwater recharge estimate at Alto Rio Grande – MG watershed
(Engenharia Agrícola, 2012-11) Pereira, Donizete dos R.; Silva, Lucas A. da; Silva, Antônio M. da; Coelho, Gilberto; Mello, Carlos R. de
Springs are outcrops of aquifers surface, and the water cycle in this environment pass through the recharge, generally defined as the amount of water added to the aquifer, which may occur locally from rainwater infiltration. This study uses the Water Table Fluctuation (WTF) method to estimate the direct recharge and a groundwater balance to estimate the deep recharge on unconfined aquifers. The WTF method employs data of the aquifer water levels and its specific yield to estimate the direct recharge. The groundwater balance considers the direct recharge estimated by the WTF method, as the water input in the system and outputs as the base flow and deep recharge. The recharge was estimated at four areas at the watershed of Alto Rio Grande city, Minas Gerais (MG) state, in Brazil. The direct recharge estimate was 121.11; 64.62; 83.99; 152.46 (mm/year) for the L1, L2, M1 and M2 areas. The effect of the presence of forest in the recharge area can prevail over slope of relief, allowing more direct recharge, even in sources with steeper relief. The runoff from the springs in the study period exceeded the direct recharge, indicating a situation in which the saturated zone feeds the vadose zone. The annual flow was above the direct recharge pointing a situation of over exploitation of the aquifer, a non sustainable situation. The specific yield of the aquifers could also have been underestimated.
Initial performance of maize in response to NPK fertilization combined with Herbaspirillum seropedicae
(Revista Ceres, 2012-11-14) Baldotto, Marihus Altoé; Baldotto, Lílian Estrela Borges; Santana, Rogério Batista; Marciano, Cláudio Roberto
The inoculation with plant growth-promoting bacteria can be a technological approach useful for increasing the production of maize. The objective of this study was to evaluate the initial performance of maize in response to application of doses of NPK combined with the inoculation of the diazotrophic bacteria Herbaspirillum seropedicae in an greenhouse experiment. The experiment consisted of six fertilizer levels: 0, 25, 50, 75, 100 and 200% of the recommended dose of NPK applied to maize inoculated and non-inoculated with H. seropedicae. At 30 days after the treatment application, the growth characteristics and nutritional status of the plants were evaluated. Plant development was influenced by fertilization, but it was enhanced by combination with the bacteria, which resulted in significant increases in the dry mass of shoots (7%) and leaf area (9%) when compared with non-inoculated plants. The results showed increases in the concentration of N (11%), P (30%) and K (17%) of maize plants in response to bacterial inoculation together with NPK compared with plants that were applied fertilize only. The greater consistency and stability response of the host plant to bacterization in the presence of chemical fertilizer indicate a promissory biotechnological approach for improving the initial growth and adaptation of maize to the cultivation environment.
Gladiolus development in response to bulb treatment with different concentrations of humic acids
(Revista Ceres, 2012-11-26) Baldotto, Marihus Altoé; Baldotto, Lílian Estrela Borges
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.
Progresso da seca da haste (Botrytis cinerea) do hibisco (Hibiscus sabdariffa) em quatro épocas e dois métodos de plantio
(Summa Phytopathologica, 2013-04-13) Oliveira, Carlos Alberto de; Souza, Paulo Estevão de; Pozza, Edson Ampélio; Pinto, José Eduardo Brasil Pereira; Barretti, Patrícia Baston
O progresso da seca da haste em hibisco foi estudado em quatro épocas e dois métodos de plantio. O delineamento experimental foi em blocos ao acaso, com quatro repetições e os oito tratamentos foram dispostos em esquema fatorial 4 (épocas de plantio) x 2 (métodos de plantio), sendo: semeadura direta em 05/02/03, 06/03/03, 05/04/03 e 15/05/03; transplantio de mudas em 24/12/02, 25/01/03, 24/02/03 e 25/03/03. Imediatamente após o surgimento dos sintomas, avaliou-se a doença a cada 10 dias até o final do ciclo, aos 205 dias, calculando-se a porcentagem de hastes infectadas por planta. Calculou-se a área abaixo da curva de progresso para a incidência (AACPI). As curvas de progresso da doença dos tratamentos foram submetidas ao ajuste dos modelos linear, exponencial, monomolecular, logístico e Gompertz. Houve interação significativa de métodos e épocas de plantio na incidência da doença. Constatou-se menor incidência da seca da haste em transplantio de mudas comparado à semeadura direta em todas as épocas de plantio. Verificou-se aumento da incidência proporcionado pelo atraso na época de plantio nos dois métodos. O modelo exponencial foi o que melhor descreveu o comportamento da doença em todos os tratamentos. As diferenças estatísticas entre os tratamentos, considerando a taxa de progresso, não refletiram a intensidade da doença no campo. Na mesma época de plantio, as quantidades inicial e máxima da doença, observadas na semeadura direta, foram superiores aos tratamentos referentes ao transplantio de mudas, coerentes com os valores da AACPI. Registrou-se uma relação direta entre queda de temperatura e aumento da incidência da seca da haste.
Physical attributes of distroferric red latosol under four eucalypt species over the long term
(Ciência e Agrotecnologia, 2013-04-18) Braga, Francisco de Assis; Braga, Rafael Malfitano; Dias Junior, Moacir de Souza; Protásio, Thiago de Paula
Planted forests have been increasingly highlighted in the Brazilian scenario, maintaining status regarding their environmental effects, among them those related with soils. The objectives of this work were to evaluate and to compare the physical attributes of a typic distroferric Red Latosol under Eucalyptus cloeziana, E. grandis, E. Pilularis and Corymbia maculata coverage, 37 years after being planted at the Federal University of Lavras campus. The soil profiles were sampled down to 1 m depth in order to analyze their particle-size distribution, porosity, structure and water retention. The results were submitted to analysis of variance, Scott-Knott multiple means comparison test, correlations and linear regression. The profiles presented appropriated soil physical conditions to provide good plant development. The bulk density and microporosity increased in depth while the total pore volume, macroporosity and aggregates stability decreased in depth. The soil profiles under E. cloeziana and C. maculata coverage presented lower density, more pores, are more structured, present lower water retention capability and lower water availability than the soil profiles under E. grandis and E. pilularis.
Frações da matéria orgânica e propriedades redox de substâncias húmicas em sedimentos de oceanos profundos
(Química Nova, 2013-05-27) Baldotto, Marihus Altoé; Gobo, Arizoli Antonio Rosa; Salomão, Marcos Sarmet Moreira de Barros; Rezende, Carlos Eduardo; Camargo, Plínio Barbosa de
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.
Leaf habit does not predict leaf functional traits in cerrado woody species
(Basic and Applied Ecology, 2013-08) Souza, João Paulo; Cianciaruso, Marcus V.; Silva, Igor A.; Manica, Lilian T.
Plant species with a high leaf life span (LLS) commonly have a low specific leaf area (SLA), leaf nitrogen per unit mass (N), and phosphorous concentration (P), whereas species with low LLS have a high SLA, N and P. However, LLS tends to be longer in species growing in low-nutrient soils and, therefore, differences in LLS and other leaf traits may not be consistent with a plant classification according to leaf habit. Here we investigated whether leaf habit is consistent with leaf economic spectrum trade-offs in cerrado (a Neotropical savanna) woody species. We analyzed the SLA, N and P of 125 woody species with a distinct leaf habit (deciduous, semideciduous, brevideciduous or evergreen). We also gathered data on the LLS (33 species), maximum net photosynthesis per leaf area (Aarea, 56 species) and per leaf mass (Amass, 31 species), comprising the most extensive database analyzed so far for the cerrado. Differences among leaf habit groups were tested using generalized linear mixed models and ANOVA. We did not find differences in SLA and N among species with a distinct leaf habit, but deciduous species had a higher leaf P concentration than evergreens. Species did not differ in LLS and Amass, but Aarea varied among groups. Semideciduous species had higher Aarea values than deciduous and brevideciduous species, but all other groups had similar Aarea values. Because of the small difference in the LLS, SLA, leaf N, leaf P and maximum net photosynthesis, we argue that deciduous, brevideciduous, semideciduous and evergreen species may not constitute different functional groups in cerrado woody species.