Soil characteristics determine the rhizobia in association with different species of Mimosa in central Brazil.

Background and aims: To evaluate the influence of soil type on the symbiosis between Mimosa spp. and rhizobia. Methods: A greenhouse experiment was carried out with trap plants using seeds of six species of Mimosa and soils from three different locations in central Brazil: Posse, Brasília and Cavalcante. Plant dry biomass and number of nodules were measured after four months. Symbiotic bacteria were isolated from nodules and their molecular identification was performed. Three housekeeping genes (16S rRNA, recA and gyrB) plus the nodC and nifH symbiotic genes were used to determine the identity of the symbionts and to reconstruct the phylogenetic relationships among the isolated nitrogen-fixing bacteria. Results: Rhizobia from the Betaproteobacterial genus Paraburkholderia (former Burkholderia) and the Alphaproteobacterial genus Rhizobium were isolated from different species of Mimosa. As in previous studies, the phylogenies of their symbiosis-essential genes, nodC and nifH, were broadly congruent with their core housekeeping genes (16S rRNA, recA and gyrB), which suggests limited or no horizontal gene transfer. Edaphic factors such as pH and fertility influenced the occurrence of these unrelated rhizobial types in the nodules on these Mimosa spp. Conclusions: Mimosa species have the ability to associate with different types of rhizobia (?- and ?-proteobacteria), suggesting low specificity between host and bacterium in experimental conditions. Soil factors such as pH, nitrogen and fertility seem to favour the predominance of certain types of rhizobia, thus influencing the establishment of symbiotic relationships. © 2017 Springer International Publishing AG, part of Springer NatureMade available in DSpace on 2018-01-31T23:58:01Z (GMT). No. of bitstreams: 1 Zillisoilcharacteristicsdetermine5.pdf: 4439951 bytes, checksum: 10b93e8a39800192a1c492f0192bc020 (MD5) Previous issue date: 2018-01-30bitstream/item/171974/1/Zilli-soil-characteristics-determine-5.pd

Tradeoffs in the quest for climate smart agricultural intensification in Mato Grosso, Brazil.

Low productivity cattle ranching, with its linkages to rural poverty, deforestation and greenhouse gas (GHG) emissions, remains one of the largest sustainability challenges in Brazil and has impacts worldwide. There is a nearly universal call to intensify extensive beef cattle production systems to spare land for crop production and nature and to meet Brazil?s Intended Nationally Determined Contribution to reducing global climate change. However, different interventions aimed at the intensification of livestock systems in Brazil may involve substantial social and environmental tradeoffs. Here we examine these tradeoffs using a whole-farm model calibrated for the Brazilian agricultural frontier state ofMato Grosso, one of the largest soybean and beef cattle production regions in the world. Specifically, we compare the costs and benefits of a typical extensive, continuously grazed cattle system relative to a specialized soybean production system and two improved cattle management strategies (rotational grazing and integrated soybean-cattle) under different climate scenarios.We found clear tradeoffs in GHG and nitrogen emissions, climate resilience, and water and energy use across these systems. Relative to continuously grazed or rotationally grazed cattle systems, the integreated soybean-cattle system showed higher food production and lower GHG emissions per unit of human digestible protein, as well as increased resilience under climate change (both in terms of productivity and financial returns). All systems suffered productivity and profitability losses under severe climate change, highlighting the need for climate smart agricultural development strategies in the region. By underscoring the economic feasibility of improving the performance of cattle systems, and by quantifying the tradeoffs of each option, our results are useful for directing agricultural and climate policy

Avaliação de híbridos de sorgo para silagem por meio da degradabilidade in situ.

O experimento foi realizado com o objetivo de avaliar a degradabilidade in situ e a cinética de degradação da Matéria Seca (MS) e Proteína Bruta (PB) das silagens de três genótipos de sorgo. Foram utilizados duas linhagens isogênicas de sorgo granífero (CMSXS 114 e CMSXS 165) e um híbrido de sorgo (BR 700 duplo propósito). O plantio dos genótipos foi realizado no verão de 2009, em canteiros de 5 m de comprimento, 3 m de largura e espaçamento de 75 cm entrelinhas. Após o corte, o material foi ensilado. Após a abertura dos silos, as amostras foram pré-secas, moídas e acondicionadas em frascos de vidro para análises de MS e PB e a digestibilidade in situ destas frações. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições e quatro tratamentos, e as médias comparadas pelo teste de Tukey ao nível de 5% de significância. Quanto à taxa de degradação da MS, a silagem da linhagem CMSXS165 sem tanino foi superior a todos os tratamentos. O genótipo da linhagem isogênica sem tanino (CMSXS 165) apresentou maior degradabilidade efetiva da PB do que a linhagem com tanino (CMSXS 114). Os resultados encontrados neste experimento permitem concluir que a presença do tanino pode reduzir a degradabilidade ruminal da MS e PB

Soil characteristics determine the rhizobia in association with different species of Mimosa in central Brazil.

Publicado First online em 13 dez. 201

Soil characteristics determine the rhizobia in association with different species of Mimosa in central Brazil.

Publicado First online em 13 dez. 201

Características agronômicas de genótipos de sorgo mutantes BMR e normais utilizados para corte e pastejo.

O experimento foi conduzido nas dependências da Embrapa Milho e Sorgo, em Sete Lagoas, MG, objetivandose avaliar as características agronômicas de genótipos de sorgo mutantes BMR e normais, sendo 11 mutantes BMR e nove normais. A semeadura foi realizada seguindo o delineamento de blocos casualizados, em três repetições, cada genótipo foi tido como um tratamento. As características agronômicas foram analisadas aos 42 dias de rebrota após o primeiro corte, quando foi avaliada a altura das plantas e a produção de matéria verde e de matéria seca. Verificou-se diferença significativa entre os genótipos para essas características. Para a altura, os valores médios oscilaram de 1,28 m para o genótipo CMSXS156AxTX2785bmr a 1,72 m para o IS10428xTX2784. Já em relação à produção de matéria verde, os valores médios variaram de 12,00 t ha-1 para o CMSXS157AxTX2785bmr a 18,93 t ha-1 para o IS10428xTX2784; e quanto a produção de matéria seca os valores médios oscilaram de 1,23 t ha-1 para o CMSXS156AxTX2784 a 2,29 t ha-1 para o IS10428xTX2784. Não houve neste experimento plantas acamadas e nem quebradas. Os resultados obtidos indicam maiores produções para os genótipos IS10428xTX2784, IS10252XTX2784 e o BR007AxTX2784

Lime application effects on soil aggregate properties: Use of the mean weight diameter and synchrotron-based X-ray mu CT techniques

The hierarchical organization of aggregates in soil is responsible for the presence of inter and intra-aggregate pores. This research aimed to investigate effects of soil surface liming, considering lime rates of 0, 10 and 15 t ha(-1), on the intra-aggregate porous system of soil aggregates with equivalent diameters of 2-4 and 1-2 mm, from 0 to 10 (A) and 10 to 20 cm (B) soil layers. These aggregates were selected by the wet sieving method carried out for determination of the mean weight diameter. Synchrotron-based computed microtomography (mu CT) of aggregates was analyzed in terms of porosity, connectivity, tortuosity, and fractal dimension. Additionally, X-ray fluorescence was used to evaluate the elemental composition of the soil aggregates. All liming effects were concentrated at layer A, where calcium percentage was elevated in aggregates from 1-2 mm class as compared to those from 2-4 mm class. Accordingly, the physical parameters studied were generally more affected in the case of smaller aggregates (1-2 mm). Liming decreased total porosity, increased tortuosity of pores, and decreased fractal dimension for 1-2 mm aggregates, which was in line with the fact that larger pores were replaced by smaller ones in 1-2 mm aggregates, as found via both quantitative and qualitative analyses. On the other hand, liming did not affect pore connectivity under any of the circumstances