Paulo Furtado Mendes Filho

Biomassa, atividade microbiana e FMA em rotação cultural milho/feijão-de-corda utilizando-se águas salinas

Resumo - O objetivo deste trabalho foi avaliar a influencia da irrigacao com agua de alta e baixa salinidade sobre variaveis microbiologicas do solo em area submetida a rotacao de cultura entre milho (Zea Mays L.) e feijao-de-corda (Vigna unguiculata L.). A area destinada ao experimento foi dividida em duas subareas, sendo realizados quatro cultivos: dois cultivos irrigados na estacao seca e dois de sequeiro na estacao chuvosa. O estudo foi conduzido em campo, utilizando-se o delineamento em blocos ao acaso, com cinco repeticoes. Nos cultivos irrigados foram usadas agua com as seguintes condutividades eletricas (CEa): 0,8; 2,2; 3,6 e 5,0 dS m -1 . Os cultivos de sequeiro foram realizados nas mesmas parcelas que foram cultivadas na estacao seca, as quais permaneceram demarcadas e identificadas. No inicio e ao final de ca da cultivo, foram coletadas amostras em duas subareas na regiao radicular das plantas, no terco medio da fileira central de cada parcela. O aumento da salinidade da agua de irrigacao promoveu aumento do numero total de esporos de fungos micorrizicos arbusculares FMA e reduziu a respiracao basal do solo, o carbono da biomassa e o coeficiente metabolico microbiano (qCO 2 ), principalmente na area cultivada com feijao-de-corda. O genero Glomus respondeu por mais de 70% dos esporos totais encontrados, sendo que essa percentagem aumentou nos tratamentos com maior salinidade nos cultivos da estacao seca. Os dados nao evidenciaram qualquer efeito negativo da salinidade residual sobre as variaveis microbiologicas avaliadas, em funcao da irrigacao com agua salina durante os cultivos da estacao seca. Palavras-chave - Estresse salino. Zea mays L. Vigna unguiculata L. Microrganismos.

Colonização micorrízica e nodulação radicular em mudas de sabiá (Mimosa caesalpiniaefolia Benth.) sob diferentes níveis de salinidade

The sabia (Mimosa caesalpiniaefolia Benth.) is a plant species native to the Brazilian northeast and brings together some fundamental features for use in rehabilitation programs of salinized areas, especially if associated with arbuscular mycorrhizal fungi (AMF) and nitrogen-fixing bacteria (BFN). The aim of this study was to evaluate the mycorrhizal colonization and root nodulation of sabia seedlings fertilized with organic compost and irrigated with water at different electrical conductivities. The experiment was carried out in a greenhouse, in a completely randomized design with a factorial scheme of 2 (presence and absence of arbuscular mycorrhizal fungi) x 2 (presence and absence of an organic compound) x 5 levels of electrical conductivity of the irrigation water (0.7, 1.2, 2.2, 3.2 and 4.2 dS m-1), and three repetitions. The results obtained indicate that: salinity reduced mycorrhizal colonization and root nodulation of the sabia seedlings; intensifying salt-stress conditions increased the mycorrhizal dependence of the sabia seedlings; the colonization of seedlings with AMF caused increases in the root-nodule dry matter of about 1900%; the arbuscular mycorrhiza reduced the pH after soil cultivation; and the addition of vermicompost had no effect on the mycorrhizal colonization of the sabia seedlings, but did increase the production of root-nodule dry matter.

Desenvolvimento e colonização micorrízica em mudas de embaúba adubadas com fosfato natural e material orgânico

A Embauba (Cecropia pachystachya Trecul) e uma especie de comportamento pioneiro, rustica e de crescimento rapido, ideal para cultivo em solos de baixa fertilidade, o que justifica sua dependencia em relacao aos fungos micorrizicos arbusculares (FMA). A simbiose dessa planta com os FMA amplia sua eficiencia na absorcao dos nutrientes da solucao do solo, principalmente os de pouca mobilidade como o fosforo, o que possibilita o uso de adubo fosfatado de baixa solubilidade na producao de mudas. Para avaliar essa possibilidade foi conduzido um trabalho em casa de vegetacao por 120 dias, no qual foi testado o fosfato de rocha natural em cinco doses de P (0; 75; 150; 300 e 600 mg L-1), sobre a colonizacao por FMA e o desenvolvimento de mudas de embauba cultivadas em substrato composto por solo natural (SN), solo natural com 50% (v/v) de solo esterilizado (SND) e solo natural com 25% (v/v) de material orgânico (SNM). Avaliou-se a altura, producao de massa seca da parte aerea, diâmetro do colo, teores de N, P, K, percentagem de colonizacao micorrizica radicular, numero de esporo de FMA no substrato, a respiracao basal do solo (RBS), o carbono da biomassa microbiana (CBM) e o quociente metabolico do solo (qCO2). O crescimento, diâmetro do colo e a producao de massa seca da parte aerea da embauba nao foram favorecidos pelos substratos e nem pelas doses de P. Todavia a colonizacao micorrizica radicular, a esporulacao, RBS, CBM e qCO2 foram influenciadas pelas adubacoes fosfatada e orgânica adicionadas ao solo.

Evaluation of Growth and Morphological Pattern of Mycorrhization in Cowpea [Vigna unguiculata (L.)] Fertilized With Phosphorus

Microorganisms perform important functions in the soil and, among these organisms, the role of arbuscular mycorrhizal fungi (AMF) in plant growth should be highlighted. AMF colonize the roots of most plant species and their beneficial functions in plant development include increased absorption of nutrients from the soil, especially those of low mobility such as phosphorus (P). Evaluating agricultural practices conducted by farmers, such as phosphate fertilization, and observing how they will influence AMF activity in benefiting plant growth should be prioritized. Thus, an experiment was conducted in greenhouse to evaluate the effect of phosphate fertilization on the growth of cowpea plants colonized by AMF and to know which morphological pattern of colonization prevails in their roots. Five P doses and a control treatment, without fertilization, were added to the soil. Cowpea plants respond to phosphate fertilization up to the dose of 240.50 mg P kg-1 soil, for shoot dry mass and in the dose of 150 mg P kg-1 soil, for plant height. The morphological pattern observed in the roots was the intermediate type, characterized by the presence of intra and intercellular hyphae and vesicles, and there was no influence of phosphate fertilization on morphology. High P contents added to the soil led to a reduction in mycorrhizal colonization in cowpea roots.

Changes in the abundance and diversity of soil arthropods in the cultivation of fruit crops

The aim of this study was to evaluate the influence of fruit-crop management (mango, guava and coconut) on the composition and distribution of soil arthropods (mesofauna and macrofauna) during seasonal periods in the Curu Valley region of the State of Ceara, Brazil. The study was carried out during the following periods: rainy/dry (July/August 2013), dry (October/ November 2013), dry/rainy (January/February 2014) and rainy (April/May 2014). Pitfall traps were used to capture the arthropods. After sorting, the Shannon-Wiener diversity index and the Pielou evenness index were calculated. Diversity values were compared in pairs using Student’s t-test (α = 0.05) in the SAS v 9.0 software (2002). The similarity of the areas and groups was evaluated by multivariate analysis employing the techniques of principal component (PCA) and factor (FA) analysis in the Statistica® software (2014). The abundance and diversity of soil arthropods in the cultivation of fruit trees vary according to the type of management and to the seasonal period in the region. The Acari, Collembola and Formicidae groups were the most abundant in each area and during the four periods of the study. The area cultivated with coconut shows better soil conditions for maintaining the arthropod community in the soil.

Atributos do Solo Relacionados com a Produção da Castanheira-do-Brasil (Bertholletia excelsa)

Neste estudo foram analisados os atributos do solo relacionados com variacoes na producao de frutos da castanheira bem como o estado nutricional da especie. As arvores foram selecionadas em parcela permanente (Caracarai, RR) e divididas em quatro classes de producao: alta, media, baixa e muito baixa. Em novembro de 2009, amostras de solo e folhas foram coletadas para se avaliar a fertilidade do solo, o numero de esporos de fungos micorrizicos arbusculares e o estado nutricional das arvores. Arvores com maior producao de frutos ocorreram associadas a maior teor de Al trocavel na camada de 0-20 cm do solo, bem como a menor valor de pH e saturacao por bases. A variavel discriminante resultante deste estudo nao foi considerada como responsavel por interferir no potencial produtivo da castanheira-do-brasil, mas serviu como indicativo de que arvores mais produtivas contribuem na remocao de bases trocaveis, favorecendo a acidificacao do solo.

Colonização micorrízica arbuscular e tolerância ao mal-do-Panamá em mudas de banana-maçã

The aim of this study was to evaluate the effect of the colonization of arbuscular mycorrhiza on the tolerance to Panama disease of the banana plant cv. maca under different sources of nutrients. A completely randomized design was employed, having a 2 x 4 factorial [2 densities of native FMA spores (D1 - 3,500 spores kg-1 soil and D2 - 7000 spores kg-1 soil) and four different concentrations of nutrient sources - three of a nutrient solution (SN 40%, SN 70% and SN 100%) and a 100% solution of bio-fertiliser (B4)], with three replications. After planting, the seedlings were inoculated with Fusarium oxysporum f.sp. cubense, and later the shoot dry matter, leaf phosphorus content, mycorrhizal colonization, soil pH and disease severity index were evaluated. The different nutrient sources affected the shoot dry matter, the phosphorus content, the mycorrhizal colonization and the disease severity index, but did not affect the pH of the soil-solution. The bio-fertiliser did not meet the nutritional demands of the plants, which remained underdeveloped, however it promoted intense mycorrhizal colonization and lower manifestations of fusarium. The latter increased under mineral fertilization.