Machado D.L.,São Paulo State University |
Pereira M.G.,Federal Rural University of Rio de Janeiro |
Correia M.E.F.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária |
Diniz A.R.,Institute Agronomia |
And 2 more authors.
Bioscience Journal | Year: 2015
In forest ecosystems, the contribution and decomposition of litterfall are the primary means of transferring nutrients to the soil, being of great importance for the sustainability of these systems. However, studies about the influence of succesional stages in the dynamics of nutrient cycling in secondary forests are scarce, especially those located in relief irregular, where are concentrated much of the Atlantic Forest fragments in southeastern Brazil. This work aimed to study the cycling of nutrients in different successional stages of submontane semideciduous seasonal forest, through of monthly and annual litterfall production, by nutrient availability and the rate of decomposition of leaf material. We studied three areas with different successional stages, located in Pinheiral, RJ: forest in initial stage (FIS), forest in intermediate stage (FINS) and forest in advanced stage (FAS). The litter production was evaluated monthly for one year (April/2009 to March/2010) through conical collector 0,21m2. The litter collected was dried and stratified into leaves, branches, and other reproductive materials (fractions unidentifiable) and weighed. Subsequently, the material was homogenized and N, P, K, Ca and Mg concentrations were determined . The decomposition of leaf material was evaluated for 120 days using litter bags. It was found annual litter of 7.47 Mg ha–1 in FIS, 8.96 Mg ha–1 in FINS and 14.7 Mg ha+ in FAS, with the leaf fraction representing, respectively, 86.4%, 80.7% and 66.1% of the total contributed. Concentration and content of nutrients, in general, were less in FIS, intermediate in FINS and higher in FAS. The litter was shown to be an important route of transfer of N and Ca to the soil, especially N in FAS and Ca in FINS and FEI. The half-life in FAS was 151 days, followed FINS (217 days) and FIS (315 days), observing the FAS greater loss of material throughout the study period. Ours results showed that the successional age affected the total amount of nutrients produced via litter, according to the structural complexity in terms of increase of plant species richness and basal area. Thereby, one can expect that, provided there are favorable conditions such as sources of propagules and dispersers, secondary forest succession in areas of relief irregular and with low fertility soils, condition the formation of a nutritionally sustainable forest. © 2015, Universidade Federal de Uberlandia.
De Lucena A.J.,Institute Agronomia |
De Faria Peres L.,Institute Geociencias |
Rotunno Filho O.C.,Escola |
De Almeida Franca J.R.,Institute Geociencias
Joint Urban Remote Sensing Event 2013, JURSE 2013 | Year: 2013
This paper presents a proposal for estimating land surface temperature (LST) for the metropolitan area of Rio de Janeiro (MARJ), Brazil, based on Landsat 5 and 7 data from 1984 to 2010. The main objective is to emphasize the need for greater accuracy in urban heat island studies, overlooking a series of essential steps to retrieve LST as close as possible to the true, including cloud masking techniques, atmospheric correction and surface emissivity. © 2013 IEEE.
Dias A.,Embrapa Agrobiologia |
Pacheco R.S.,Institute Agronomia |
Dos Santos S.G.,Institute Agronomia |
Xavier G.R.,Embrapa Agrobiologia |
And 2 more authors.
Revista Caatinga | Year: 2014
The biocontrol of soilborne plant pathogens represents a promising approach from the environmental and practical points of view. Fluorescent pseudomonad rhizobacteria are well known by their antagonistic capacity towards several plant pathogens due to a diversity of antimicrobial metabolites they produce. This study was conceived to select and characterize rhizobacteria having antagonistic potential towards the pathogenic fungi Rhizoctonia solani and Sclerotium rolfsii. A total of 94 bacterial strains isolated from the rhizospheres of four vegetable species under organic cultivation were evaluated. Twenty-two strains which predominate in lettuce and rudbeckia rhizospheres showed identical biochemical profiles to Pseudomonas fluorescens, while in kale and parsley rhizospheres identical profiles to Pseudomonas putida (subgroups A and B) strains prevailed. Two types of antagonism were verified in vitro and defined as competition and inhibition of mycelial growth. Sixty percent of the evaluated strains showed antagonistic potential and, among those, 24 strains expressed antagonism to both target fungi, with P. fluorescens being the most representative bacterial species. This work clearly identified a number of strains with potential for use as plant growth-promoting and biocontrol of the two soilborne fungal pathogens in vegetable crops production systems.
de Lima A.A.,Institute Agronomia |
Fernandes Jr. P.I.,Embrapa Semiarido |
Passos S.R.,Institute Agronomia |
de Paulo F.S.,Institute Agronomia |
And 5 more authors.
Revista Brasileira de Ciencia do Solo | Year: 2012
Mucuna species are widely used as green manure, and little information is available about rhizobia that can nodulate them. The objective of this study was to evaluate the diversity and ability of bacteria isolated from symbiotic nodules of velvet bean (Mucuna pruriens (L.) DC.) and Mucuna deeringiana (Bort.) Merr. From the nodules of either mucuna species, grown in pots with soils from an agroecological system, 80 bacteria were isolated. The selected bacteria were classified and used to assess the symbiotic capacity. The diversity assessment of the isolates was based on cultural characteristics on YMA medium and the technique of restriction analysis of PCR products of 16S rDNA. The inoculation of Mucuna pruriens with five and Mucuna deeringiana with two isolates increased the aboveground biomass. Most isolates grew rapidly and acidified the culture medium. Restriction analysis showed low similarity of the reference strains with the bacterial isolates, suggesting the existence of isolates belonging to new groups that are able to nodulate the two mucuna species.
Morales M.,Institute Agronomia |
Moratinos H.,Institute Agronomia |
Gonzalez T.,Institute Agronomia |
Madriz P.,Institute Agronomia
Revista de la Facultad de Agronomia | Year: 2012
Laboratory and field test were conducted in order to evaluate the effect of two fungicides on physiology and health quality of Cimarron and FONAIAP 1 rice seeds varieties, under storage conditions. Samples of each cultivar were treated with fludioxonil at 2 L.Tm-1 of seed (25 g a.i.L-1), carboxin+thiram at 250 mL.100 kg-1 of seed (200 g a.i.L-1) and untreated control with distilled sterile water was used. The samples were storage at 11°C and 75% relative humidity (RH) during 240 days. The variables were measured in a completely randomized design, with four replications in split plot design: where varieties were at two levels (Cimarrón and FONAIAP 1), the fungicides at three levels (fludioxonil, carboxin+thiram and the untreated control with distilled water) and twelve levels of storage (5, 7, 15, 30, 45, 60, 90, 120, 150, 180, 210 and 240 days). There were estimated germination percentage and vigor throughout several methodologies. In addition it was determined the seed fungal incidence with agar plate (potato- dextrosa-agar) method. The epicotyl dry biomass of seedling treated with fludioxonil was higher than those treated with carboxin+thiram and untreated control. The seeds treated with fludioxonil and carboxin+thiram presented lower incidende of Fusarium moniliforme than untreated seeds. During storage conditions, the seed germination was greater than 80%. Among seeds treated with fludioxonil and carboxin+thiram, the incidence of Fusarium moniliforme decreased. The treatment of rice seeds with fungicides did not affect their physiology and increased health quality.