Resumo As características bióticas e abióticas dos solos variam substancialmente em função dos sistemas de cultivo empregados em ambientes semiáridos. Sistemas de cultivo que favoreçam a manutenção dos teores de carbono orgânico no solo (e.g., provisão de habitat) podem influenciar positivamente a diversidade da comunidade da fauna edáfica e a qualidade do solo. Objetivou-se neste estudo avaliar o efeito de diferentes sistemas de cultivo (e.g., plantio direto vs. integração lavoura-pecuária-floresta) sobre as propriedades químicas do solo, a composição da fauna edáfica e a qualidade de um Planossolo Nátrico em condições semiáridas do Nordeste do Brasil. Usando métodos combinados de coleta de amostras de solo para caracterização química com a extração de indivíduos da fauna edáfica e sua identificação taxonômica foi observado que ambos sistemas de plantio avaliados neste estudo promoveram incrementos nos teores de carbono orgânico no solo e fósforo disponível em relação ao controle. Foram observadas 11 ordens e mais 3 grupos de larvas (Larvas de Coleoptera, Diptera e Lepidoptera) da fauna edáfica, contudo, apenas Araneae, Coleoptera, Diptera e Hymenoptera foram influenciadas de forma significativa (p < 0,01) pelos sistemas de cultivo. Além disso, os índices de qualidade do solo em todos os sistemas de cultivo foram superiores em comparação ao controle, o que reforça a hipótese de que sistemas de plantio que consideram a manutenção de habitat e energia para fauna do solo contribuem para o estabelecimento de uma teia trófica diversificada e provisão de serviços ecossistêmicos favorecendo a ciclagem de nutrientes. Por fim, o estudo demonstra a importância de considerar sistemas de cultivo que promovam a manutenção dos teores de carbono orgânico no solo e a provisão de condições ideais no ecossistema solo para sustentar uma comunidade da fauna edáfica e funcional em condições semiáridas.

Abstract Soil biotic and abiotic characteristics are influenced by crop system in semiarid environments. Crop systems which promote soil organic carbon content at high levels could positively promote soil fauna diversity and soil quality. Our aim with this study was to evaluate the effects of crop systems (No-tillage vs. Integrated crop-livestock-forestry system) on soil chemical properties, soil fauna composition, and soil quality in a Planossolo at semiarid environment from Brazilian Northeast. Combining protocols for soil chemical characterization and soil fauna extraction and identification, we observed that both crop systems studies increased soil organic carbon and available P when compared to control treatment. We found 11 orders plus 3 larvae groups (Larvae of Coleoptera, Diptera, and Lepidoptera) from soil fauna organisms, however, only Araneae, Coleoptera, Diptera, and Hymenoptera were significantly affected (p < 0.01) by crop systems. We also observed that soil quality index in all crop systems studies was higher than in the control treatment, and it corroborates with the follow hypothesis that crop system which consider habitat and energy maintenance for soil fauna contributes to a diverse soil food web establishment that favours soil nutrient cycling. Our results highlight the importance to consider crop systems which promotes soil organic carbon and ideal condition into soil ecosystem to sustain a diverse and function soil fauna community in semiarid conditions.

Objetivou-se neste estudo avaliar a performance de genótipos no rendimento e nas componentes de rendimento em feijão fava produzidas em duas épocas com objectivo de selecionar as que se revelarem altamente produtivas e adaptadas as condições do local de estudo. Para tal foi realizado um experimento de campo em blocos casualizados em esquema fatorial (nove variedades vs. dois anos de cultivos) e quatro blocos. Foram avaliados comprimento e largura da vagem, vagens.planta-1, sementes.vagem-1, massa de 100 sementes e produtividade de grãos. As variedades Cara Larga, Eucalipto, Rosinha e Roxinha apresentaram os maiores valores de vagens.planta-1. A variedade Orelha de Vó se destacou quanto a massa de 100 sementes e produtividade de grãos. Correlações negativas foram encontradas entre massa de 100 sementes, vagens.planta-1 e sementes.vagem-1. As variáveis sementes.vagem-1, massa de 100 sementes e vagens.planta-1 são úteis para estimar a produtividade variedades crioulas de fava avaliadas.

The aims of this study were: (i) to evaluate the yield of lima bean landraces; (ii) to determine the dissimilarities among landraces of lima bean; and (iii) to assess linear correlations among the yield components of lima bean landraces grown on sandy soils of the Brazilian semi-arid. A field experiment was carried out using a randomized block design with eighteen treatments (nine lima bean landraces vs. two years of cultivation) with four blocks. We evaluated pod length and width, pods.plant-1, seeds.pod-1, one-hundred seed weight and yield. Cara Larga, Eucalipto, Rosinha and Roxinha landraces presented the highest values of pods.plant-1. Orelha de Vó presented the highest one-hundred seed weight and yield. Negative correlations were found between one-hundred seed weight, pod.plant-1 and seeds.pod-1. The yield components seeds.pod-1, one-hundred seed weight and pods.plant-1 are useful components to estimate yield of lima bean landraces.

Abstract Many plant species from Brazilian semi-arid present arbuscular mycorrhizal fungi (AMF) in their rhizosphere. These microorganisms play a key role in the establishment, growth, survival of plants and protection against drought, pathogenic fungi and nematodes. This study presents a quantitative analysis of the AMF species associated with Mimosa tenuiflora, an important native plant of the Caatinga flora. AMF diversity, spore abundance and root colonization were estimated in seven sampling locations in the Ceará and Paraíba States, during September of 2012. There were significant differences in soil properties, spore abundance, percentage of root colonization, and AMF diversity among sites. Altogether, 18 AMF species were identified, and spores of the genera Acaulospora, Claroideoglomus, Dentiscutata, Entrophospora, Funneliformis, Gigaspora, Glomus, Racocetra, Rhizoglomus and Scutellospora were observed. AMF species diversity and their spore abundance found in M. tenuiflora rhizosphere shown that this native plant species is an important host plant to AMF communities from Brazilian semi-arid region. We concluded that: (a) during the dry period and in semi-arid conditions, there is a high spore production in M. tenuiflora root zone; and (b) soil properties, as soil pH and available phosphorous, affect AMF species diversity, thus constituting key factors for the similarity/dissimilarity of AMF communities in the M. tenuiflora root zone among sites.

Biological invasions pose a serious threat to native semi-arid areas of Brazil, especially in areas of the state of Ceará that are typically invaded byCryptostegia madagascariensis, an exotic plant species from Madagascar. However, how this biological invasion influences the composition of the arbuscular mycorrhizal fungal (AMF) community and how this affects further invasion by C. madagascariensis is not well known. Here we tested how inoculation with species of AMF affects the development of this invasive plant. We analyzed and compared the AMF community composition of four different stages of biological invasion by C. madagascariensis, and examined the effects of inoculation with these four AMF communities, plus a dominant AMF species (Rhizoglomus intraradices) on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas of plants of C. madagascariensis. We found that all studied treatments (except the inoculum from the native plant root zone) promoted the growth of C. madagascariensis and lead to a higher P concentration. Our results demonstrate that the invader might be altering the composition of the AMF community in field conditions, because inoculation with this community enhanced invader growth, root colonization, and P uptake.