Effect of tillage and crop on arbuscular mycorrhiza

Large-scale inoculation with arbuscular mycorrhizal fungi (AMF) is generally impractical in most regions and we have little understanding of the factors that determine inoculation success. Nevertheless, the ability to take full advantage of indigenous AMF for sustainable production needs to be developed within cropping systems. We used part of a long-term field experiment to understand the influence of tillage and the preceding crop on AMF colonization over the growing season. Arbuscular mycorrhiza colonization rate was more affected by treatment (tillage or the combination of crop and preceding crop) than by the total number of AMF spores in the soil. Conventional tillage (CT) had a statistically significant negative effect (P £ 0.05) on spore numbers isolated from the soil, but only in the first year of study. However, the AMF colonization rate was significantly reduced by CT, and the roots of wheat, Triticum aestivum, L, cv. Coa after sunflower, Helianthus annuus L., were less well colonized than were those of triticale, X Triticosecale Wittmack, cv. Alter after wheat, but the affect of tillage was more pronounced than was the effect of crop combination. Under no-till there was a significant increase in AMF colonization rate throughout the sampling period in both wheat and triticale,indicating that the extraradical mycelium previously produced acted as a source of inoculum. In general, triticale showed greater AMF colonization than wheat, despite the preceding crop being less mycotrophic. Under these experimental conditions, typical of Mediterranean agricultural systems, AMF colonization responded more strongly to tillage practices than to the combination of crop and preceding crop

NO-TILL PROVIDES THE OPPORTUNITY TO MANAGE UNDERGROUND INTERACTIONS BETWEEN ARBUSCULAR MYCORRHIZAL FUNGI, WEEDS AND CROP PLANTS UNDER MEDITERRANEAN CONDITIONS

Early colonization of crop roots by arbuscular mycorrhiza (AM) is considered beneficial but its importance likely depends on the possible stresses faced by the host plant. Manganese toxicity is one such stress that AM can alleviate. Colonization initiated by extraradical mycelium (ERM) is faster than other sources of inoculum. No-till creates the possibility of encouraging inoculation via this source. At seeding time the ERM available for colonizing plants under no-till would have developed in association with previous crops or those weeds that germinated after the first autumn rain. However, the long, hot and dry summer under Mediterranean conditions might reduce the effectiveness of the ERM to colonize the new crop. The hypothesis that an intact ERM developed by weeds can affect the earlier AM colonization of wheat and alleviate Mn toxicity was tested in a pot experiment. Two mycotrophic (Ornithopus compressus L., Lolium rigidum Gaudin), and one non-mycotrophic (Silene galica L) weed species were grown for 7 weeks before being controlled with Glyphosate (the ERM remaining intact) or by mechanical disturbance (which also disrupted the ERM). Wheat was then planted and allowed to grow for 21 days. AM colonization, plant dry weight and shoot nutrient content were evaluated for both weeds and wheat. When an intact mycelium was present at the seeding of wheat (treatments with Ornithopus compressus and Lolium rigidum controlled by Glyphosate) there was a threefold increase in the AM colonization rate and growth of the crop compared with results for all the other treatments. The enhanced growth of wheat was associated with an alleviation of Mn toxicity, consistent with the hypothesis. However, there was a significant difference of the wheat growth after Ornithopus and Lolium (1.9 times), suggesting functional diversity within mycotrophic weeds and crops

Potencialidades do teatro de fantoches na educação rodoviária: uma abordagem no âmbito da educação para a cidadania

Dissertação de mest., Educação Artística, Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, 2007Ao longo da presente pesquisa – Potencialidades do teatro de fantoches na educação rodoviária: uma abordagem no âmbito da educação para a cidadania - debruçamo-nos, num primeiro momento, sobre a clarificação de conceitos respeitantes ao enquadramento do tema, nomeadamente quanto à Educação Rodoviária que se aplica às crianças em Portugal, aos seus princípios, objectivos e alguma legislação no nosso país acerca da mesma. Em seguida, abordamos a problemática do teatro como objecto facilitador de mudanças a nível social e cultural, nomeadamente em relação à importância atribuída ao fantoche na transmissão de certas competências básicas essenciais para o desenvolvimento global das crianças. Estas competências referem-se, mais concretamente à aquisição de comportamentos mais seguros, mais conscientes e defensivos ao circularem como utentes da via pública. Surge então, como forma de dar resposta a este problema cada vez maior na nossa sociedade, a necessidade de implementar um projecto junto da comunidade escolar que tem como objectivo contribuir para a diminuição da sinistralidade nas nossas estradas, cada vez maior entre as camadas mais jovens. Progressivamente são descritas as várias experiências levadas a cabo com fantoches, de modo a demonstrar o contributo que estes podem representar na transmissão de regras de segurança às crianças, principalmente quanto à adopção de comportamentos seguros no trânsito. Procurando desenvolver uma pesquisa de carácter essencialmente qualitativo, tornou-se claro desde o início que este tipo de estudo viria a tornar-se uma investigação i - acção, baseado na prática das educadoras de uma escola de trânsito, onde foi proposta esta experiência. De modo a tornar esta uma pesquisa mais consistente, enveredei por caminhos investigativos muitas vezes usados noutro tipo de estudo, utilizando nomeadamente grelhas de observação, testes escritos e registos do diário de bordo, criadas ou adaptadas aos objectivos inerentes ao estudo. Estes instrumentos foram aplicados a dois grupos diferentes de crianças; o primeiro grupo já havia frequentado aulas nesta escola, tendo assistido a aulas leccionadas com meios áudio - visuais (que chamarei Situação A. V.) e ao qual foi feita uma apresentação com fantoches( Situação F.). O outro grupo, que apesar de não ter frequentado esta escola em ocasiões anteriores elaborou fantoches e criou uma história com os mesmos conceitos inerentes à temática da Educação Rodoviária, inseridos num programa de fantoches realizado nas férias da Páscoa (Situação P). Sintetizando, podemos referir que esta pesquisa teve aspectos muito positivos, tais como a capacidade de tomada de consciência de que os outros também existem e por vezes nós temos que nos colocar no seu lugar, de modo a entendermos as suas perspectivas antes de os recriminar, atingindo assim um grau de maturidade considerável, ao longo da vida. Permite, e permitiria se de futuro houvesse oportunidade de continuarmos a observar os comportamentos destas crianças no seu dia – a - dia, levar-nos a crer que este tipo de abordagem leva a uma maior consciencialização por parte das crianças acerca da sua ii exposição aos perigos, permitindo de futuro a alteração de condutas incorrectas no trânsito; no entanto será demasiado optimista aspirar a que um único estudo o pudesse fazer, sendo pois de todo o interesse dar continuidade a este tipo de trabalho, em cooperação com outras entidades, tais como a Escola Segura, a Prevenção Rodoviária Portuguesa e as próprias escolas, professores e mesmo com encarregados de educação ou comunidade em geral

Impact of tillage system on arbuscular mycorrhiza fungal communities in the soil under Mediterranean conditions.

A more diverse arbuscular mycorrhiza (AM) fungal community should be more versatile and resilient to variation in environmental conditions over space and time. To evaluate the effect of no-till and conventional tillage systems, AM fungal diversity was assessed as part of a long term field experiment by sequencing of DNA, extracted from soil, that encoded the large ribosomal sub-unit and was obtained by nested-PCR. In comparison with no-till, conventional tillage decreased AM fungal diversity by 40%. Differences between treatments in the frequency of the operational taxonomic units (OTUs) present in soil, confirm that AM fungi are differently vulnerable to soil disturbance

Qualitative assessment of access control in a database management system

This paper presents a qualitative assessment of access control in database management system to guide those who wish to implement a discretionary or/and non-discretionary access control model and need some support to choose the access control in database management system (DBMS) best suited to their security requirements. To accomplish this we apply the core concepts related to access control models, and the metrics in NISTIR 7874. The result of this work shows how the database management system chosen, MS SQL Server 2012 supports the core concepts and the most popular access control models: RBAC, DAC and MAC, all these based on NIST 7874 metrics

Potential value of arbuscular mycorrhiza in the agricultural systems of Alentejo region - Portugal

The Alentejo region, located in the south of Portugal and occupying a third of the continental part of the country, is the region with the greatest potential for small grain production. It produces more than 80% of the total national wheat harvest, the main small grain cereal crop, despite small average yields per unit land area. The restrictions to yield are largely imposed by its Mediterranean climate, with dry and hot summers and cold and wet winters. Soil limitations can also constrain yield. Development of biomass up to the flowering stage is critical for achieving good grain yields in wheat. Consequently, agronomic management practices, including appropriately designed crop rotations, focused on achieving good early crop development, together with low input systems based on no-till, and a rational use of nutrients, can contribute, to increased productivity in the region. A possible mean of improving the use of nutrient resources is through the improved management of naturally occurring symbioses like arbuscular mycorrhiza. Arbuscular mycorrhiza (AM), a symbiosis between the roots of a wide range of plants and obligatory symbiotic fungi, is commonly mutualistic, the long-term compatible interactions being based on a bidirectional nutrient transfer between symbionts. Fungal symbionts benefit from the photosynthates produced by the plants, while the latter gain because of the increased volume of soil that can be explored by the extraradical fungal mycelium. This enhanced soil exploration is one of the most obvious advantages of mycorrhizal formation and results in the ability to take up more nutrients, particularly those that have limited mobility in soil, such as phosphorus. In addition other benefits associated with AM plants are: alleviation of water stress, protection from root pathogens, tolerance to toxic metals and the stabilization of soil aggregates promoted by extraradical hyphae, globally conferring to AM a great potential to contribute to sustainable crop production systems. Considering the impracticality of inoculating soil on a large scale, the objectives were focused on the potential value of AM under Mediterranean conditions and how they could be managed within the agricultural system of Alentejo region, assuming that if there is adequate AM colonisation, benefits would directly or indirectly, sooner or later, accrue to the crop. In a field experiment preformed to study the effect of soil disturbance (notill and conventional tillage systems) on AM colonisation of wheat over the vegetation cycle the results indicated that mycorrhizal formation in wheat and AM fugal spore numbers were greater in no-till than under a conventional system, despite the high level of soil available phosphorus. Results also showed that under field conditions, AM colonisation of winter wheat increased gradually until late spring and then declined, following root development. Once AM colonisation of wheat under Mediterranean conditions was confirmed at the field and that there was better colonisation under no-till systems, where the extraradical mycelium was kept intact, the next objective was to determine the ability of this mycelium to remain infective for the next crop. The maintenance of a high colonisation potential under the Mediterranean summer conditions is essential because it likely determines the time frame (from one cropping year to the other) and the possibilities (faster or slower colonisation) for AM to influence early crop development. Extraradical mycelium of native AM fungi (AMF) survived the dry and hot summer season and started new colonisations at the onset of the growing season, especially when it was not adversely affected by soil disturbance. The proper management of weed populations that emerge after the first autumn rains might provide a valuable too), functioning as a bridge, to ensure a quick and efficient AM colonisation of wheat young seedlings and help to assure a good early development known to be critical for successful wheat crop in Alentejo region. In a series of pot experiments using weed species chosen according to their relevance in regional agronomy, it was confirmed that allowing weeds to growth until extraradical mycelium is well established (one month) and then using herbicide to control them, preserves the extraradical mycelium network and greatly benefits initial colonisation of the crop and permits early nutrient acquisition. Considering there are pronounced plant x fungus interactions, a more diverse AM fungal community offers more possibilities for functional AM symbioses to establish. ### /RESUMO - A região do Alentejo situa-se no Sul de Portugal e corresponde a cerca de um terço do território continental. Por uma série de razões como sejam a situação geográfica o relevo e a dimensão da propriedade, é a região do país que apresenta maior potencial para a produção cerealífera, contribuindo com cerca de 80% da produção nacional de trigo, até ao momento o principal cereal produzido em Portugal. No entanto, devido em grande medida a limitações edafoclimáticas, as produtividades obtidas são relativamente baixas quando comparadas com outros países europeus. O clima Mediterrânico, caracterizado por Verões quentes e secos e Invernos frios e chuvosos, obriga à utilização de variedades de ciclo relativamente curtos, para além disso a distribuição de precipitação é extremamente irregular provocando grandes oscilações de produção de ano para ano. Nestas condições, e para os cereais de Inverno no geral, a biorriassa, acumulada até à floração é determinante para a garantia de um bom enchimento do grão, por isso o crescimento inicial da cultura pode ser decisivo para alcançar uma boa produtividade. Os solos são na sua maioria relativamente pobres. Derivados de xistos ou granitos, apresentando baixos teores de matéria orgânica, pH ligeiramente ácido e média capacidade de troca catiónica. A adesão de Portugal à Comunidade Europeia em 1986, e a obrigatoriedade em seguir as directivas da Política Agrícola Comum (PAC) cada vez mais baseadas na redução de subvenções aos agricultores, exigiu o repensar do sistema agrícola da região. A procura de sistemas de produção mais sustentáveis do ponto de vista ambiental e financeiro tornou-se obrigatória para a sobrevivência do sector agrícola. Assim, a aplicação de fundos estruturais no desenvolvimento e aquisição de novos meios de produção, o recurso a sistemas mais extensivos, o aumento da mecanização e o uso mais racional de factores de produção, têm vindo a operar uma mudança significativa no sistema agrícola do Alentejo. Exemplo disso mesmo é o recurso cada vez mais generalizado à técnica de sementeira directa, actualmente praticada em várias culturas (trigo, milho, girassol) em mais de 50 000 ha. Sistemas de baixo input baseados na sementeira directa, associados a um correcto delineamento da rotação de culturas e ao uso racional dos nutrientes são, em termos práticos, potenciais geradores de aumentos da produtividade. Neste contexto o recurso a simbioses que ocorrem de forma natural, como as micorrizas arbusculares, pode constituir uma importante via para a exploração mais adequada dos nutrientes do solo. As micorrizas arbusculares (AM) são simbioses entre a raiz de uma grande diversidade de plantas e fungos do solo que são simbiontes obrigatórios, os fungos micorrízicos arbusculares (AMF). Esta associação simbiótica é normalmente mutualista, baseando-se na troca bidireccional de nutrientes. O fungo recebe da planta os produtos resultantes da actividade fotossintética e a planta, por sua vez, beneficia de uma série de vantagens decorrentes da exploração de um maior volume de solo proporcionado pelo micélio extraradical que se desenvolve, sendo a absorção de nutrientes, nomeadamente os menos móveis como é o caso do fósforo, a mais óbvia. Contudo, para além desta, outras vantagens são atribuídas às AM: alívio do stress hídrico, protecção contra agentes patogénicos, tolerância a metais pesados e estabilização dos agregados do solo, mostrando assim um enorme potencial no contributo para a produção agrícola sustentada. Pretendeu-se com o presente trabalho compreender o potencial associado às AM, em situação de clima Mediterrânico, no contexto do sistema agrícola Alentejano, no sentido de através de práticas agrícolas adequadas valorizar os benefícios proporcionados pela micorrização, numa óptica de sustentabi 1 idade do sistema agrícola. Assumiu-se que uma vez estabelecida a micorrização, os benefícios daí decorrentes, directa ou indirectamente, mais cedo ou mais tarde, recairiam sobre a cultura. Assim, no sentido de desenvolver conhecimentos que elucidassem sobre a ecologia funcional das micorrizas arbusculares no sistema agrícola em apreço, adoptou-se uma abordagem multidisciplinar de modo a que a integração e análise da informação a diferentes escalas pudesse ser feita

Summer survival of arbuscular mycorrhiza extraradical mycelium and the potential for its management through tillage options in Mediterranean cropping systems

The potential to manage arbuscular mycorrhizal (AM) colonisation within Mediterranean agricultural systems likely depends on the summer survival of the extraradical mycelium. To investigate this further a three-stage experiment was undertaken. The first stage was the creation of two contrasting levels of extraradical mycelium development, achieved by two contrasting levels of soil disturbance (typifying full tillage or no-till).. In the second stage this differential mycelial inoculum was subjected to Mediterranean summer temperature and soil water regimes, representing the post-harvest fallow. During the third stage, corresponding to the next growing season, its survival was evaluated without further soil disturbance (typifying no-till conditions) using wheat as host crop. The results clearly indicated that the extraradical mycelium survived the prevailing summer conditions. Knowing that extraradical mycelium can survive over the Mediterranean summer encourages the use of tillage systems that minimize mechanical disturbance of the soil, such as no-till. Knowledge gained in this study suggests that by making the appropriate choice of crops to establish a mycorrhizal-supportive rotation there can be opportunities for agro-ecosystem management to benefit from the symbiotic relationship

The importance of no-till in the development of cropping systems to maximise benefits of arbuscular mycorrhiza symbiosis

The symbiosis of arbuscular mycorrhizal fungi (AMF) with plant roots presents several benefits to agricultural systems, including improved soil structure, resistance of crops to drought and soil pathogens, and its importance will increase in the future due to the scarcity of P reserves in the world. No-till is a powerful tool to manage AMF in the cropping systems as it allows the use of ERM developed in the previous year and the ERM developed by weeds in the beginning of the cropping year, as a major source of inoculum for the new crop. Therefore the design of crop rotations to take full advantage of AMF symbiosis, like an enhanced ability to uptake P, must consider the tillage system to be adopted and an appropriate weeds management

Soil and weed management for enhancing arbuscular mycorrhiza colonisation of wheat

Tillage and weed control are critical components of cropping systems that need to be combined such that crops benefit from reduced competition. However, weeds may also contribute to the biological diversity within the agro-environment. This greenhouse study investigated whether common weeds of arable cropping systems were suitable host plants for arbuscular mycorrhizal fungi (AMF), allowing the development of extraradical mycelium (ERM) that can contribute to the early colonization of a following wheat crop, especially in the absence of soil disturbance. Weeds were allowed to grow for up to 2 months before being controlled by soil disturbance or herbicide application (glyphosate or paraquat). Pregerminated wheat seeds were then planted. Chemical control of the weeds prior to sowing enhanced the early arbuscular mycorrhiza (AM) colonization rate of wheat roots, whereas mechanical disturbance was less acceptable as a method of weed control for rapid AM colonization. The type of herbicide (contact or systemic) had no impact on colonization of the wheat crop. Enhanced AM colonization promoted early P acquisition and growth of the crop. Appropriate management of weeds emerging between two consecutive cropping seasons coupled with no-till soil management could ensure a quick and efficient AM colonization of the following wheat plants