Micorrizas

Per Micorriza (dal greco mykos: fungo, e rhiza: radice) si intende un particolare tipo di associazione simbiotica tra un fungo ed una pianta superiore, localizzata nell'ambito dell'apparato radicale del simbionte vegetale, e che si estende, per mezzo delle ife o di strutture più complesse come le rizomorfe, nella rizosfera e nel terreno circostante. http://it.wikipedia.org/wiki/Micorriza Una camminata tra due alberi. Il primo si trova presso Arte nel Chianti, Montespertoli (FI), il secondo nel Parco d'Arte di Poggio Valicaia, Scandicci (FI). Agli alberi è appeso un semacode, attraverso il quale si accede ad un sito che connette virtualmente i due alberi. http://wood-wide-web.blogspot.it

El suelo sirve de soporte para las plantas, provee los minerales necesarios para su desarrollo, y es el hábitat de los microorganismos que facilitan su nutrición, contribuyendo además en la transformación del material parental que lo origina hasta la formación de un horizonte donde interactúan raíces y organismos; estas interrelaciones inciden en la interacción suelo-plantamicroorganismos- ambiente y repercuten, de forma directa, en el crecimiento y desarrollo de las especies vegetales; en este sentido el presente documento parte de la pregunta de si el olivo (Olea europea L.) adaptado a las condiciones edáficas y climáticas de la región del alto Ricaurte en Boyacá- Colombia se convierte en una alternativa productiva, económica y para la recuperación de suelos degradados del lugar. Al respecto diferentes estudios en la zona han encontrado que las condiciones físicas químicas y biológicas de la zona rizosferica de dichas plantas han mejorado, y se logra un crecimiento y desarrollo llegando a ser productivas; el propósito de esta revisión fue obtener información que permita comprender los procesos en la rizósfera de los árboles para entender la dinámica en la absorción de nutrientes en el trópico dado que de ella depende la cantidad y calidad de las aceitunas cosechadas; no obstante, la falta de prácticas culturales como la poda indispensables para la producción en el olivo. Los datos más importantes encontrados revelan que las poblaciones de microorganismos son diversas y en cantidades similares o superiores respecto a otros estudios en zonas tradicionalmente productoras, sin embargo la floración y fructificación no se concentra en una sola época del año.

Arbuscular mycorrhizas are one of the most widespread mutualistic symbioses which occur between roots of most herbaceous and tropical trees and a small group of root colonizing fungi, Order Glomales. This symbiosis is characterized by the movement of mineral nutrients acquired by the fungi towards the plant in exchange for providing the fungi with carbon compounds. In Mexico, the taxonomic diversity of arbuscular mycorrhizal fungi (AMF) has been poorly studied, since most of studies have been focused to determine plant responses to mycorrhiza without considering the origin or identity of the endophyte. In this country 44 species of AMF have been recorded, representing 29% of the worldwide known species. Most of these records come from agricultural systems and only seven species come from natural ecosystems. These 44 species have been only found in 11 of the 32 states of Mexico. Even though the taxonomic knowledge and handling of these fungi is quite limited, field work with plants inoculated in greenhouse has been carried out in the last years. Nevertheless, information is required regarding field persistence of the endophyte and its effect on soil microbiota diversity. Knowledge of the composition and diversity of AMF is important for proper handling of soil-plantfungus interaction in order to achieve sustainable systems.

El abeto (Abies religiosa) es una especie forestal económica y ecológicamente importante para nuestro país. Desde tiempo atrás se le han dado múltiples usos y actualmente se reconoce su alto valor estético y ecológico. A la fecha, todavía no se cuenta con un programa para el manejo adecuado y completo de esta especie, principalmente por la falta de conocimiento sobre sus requerimientos ecológicos y las principales interacciones ecológicas que establecen estos árboles durante su ciclo de vida, como es el caso de la micorriza. Por lo tanto, en el INBIOTECA (Instituto de Biotecnología y Ecología Aplicada) es importante continuar generando el conocimiento que eventualmente permitirá plantear un mejor manejo de las poblaciones de oyamel, esperando que dicho esquema llegue a ser sostenible tanto en términos económicos como ecológicos.

The present work aimed to evaluate the effetc of two types of substratum (S1 and S2), in the presence or absence of arbuscular mycorhizal fungi (AMF), on Schinus terebinthifolius seedlings, using tubes of 280 mL. The experiment was carried out in greenhouse at Departamento de Solos, Instituto de Agronomia, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, to June from September 2005. S1 and S2 were constituted by a mixture (in volume), previously disinfested, of rocks’s fosfato (10%), washed thick sand (30%), clay (30%) and organic matter (30%). For S1, the source of organic matter was industrial residue of synthetic rubber production (LETRIP), whereas for S2, bovine manure. The experimental design was completely randomized in a split-plot with 24 replicates and 6 plants per plot. At 120 days after experiment instalation, S2 showed to be superior than S1 for most of the datas (height, diameter, shoot and root dry mass, N, P and K shoot concentrations, and N root concentration). There wasn’t any significant difference between the inoculated and not inoculated treatments, probably because of the high nutrients concentration in S1 and S2. And so it was the reason of the absence of root colonization in S2. LETRIP played a protector effect in native AMF spores against fungicide action, which permited root colonization in S1 without inoculation. In conclusion, S2 was more indicated to S. terebinthifolius seedling production.
Keywords: Forestry seedlings production; mycorrhizal fungi; disturbed areas.

Resumo: Avaliou-se a influência de dois tipos de substrato (S1 e S2), na ausência e na presença de inoculação de fungos micorrízicos arbusculares (FMA), na produção de mudas de Schinus terebinthifolius em tubetes de 280 mL. O experimento foi realizado em casa de vegetação do Departamento de Solos do Instituto de Agronomia, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, no período de junho a setembro de 2005. S1 e S2 se constituíram numa mistura (em volume), previamente desinfestada, de fosfato de rocha (10%), areia grossa lavada (30%), material argiloso (30%) e matéria orgânica (30%). Para S1, a fonte de matéria orgânica foi resíduo industrial de produção de borracha sintética (LETRIP), enquanto que para S2, esterco bovino curtido. O delineamento experimental foi o inteiramente casualizado, em esquema de parcelas subdivididas, com 24 repetições, com 6 plantas por parcela. Aos 120 dias após a montagem do experimento, observou-se que S2 proporcionou às mudas ganhos significativos em praticamente todas as variáveis analisadas (altura, diâmetro, massa seca de parte aérea e de raiz, teor de N, P e K na parte aérea, e de N na raiz), em comparação com S1. Não houve diferença significativa entre os substratos quanto à ausência e presença de FMA, possivelmente em função dos elevados teores de nutrientes em S1 e S2. A esse mesmo fato se atribuiu a ausência de colonização de raízes por FMA em S2. O LETRIP desempenhou efeito protetor-encapsulador de esporos de FMA nativos contra a ação do fungicida, o que permitiu a colonização de raízes em S1 na ausência de inoculação. Portanto, S2 mostrou ser mais indicado para a produção de mudas de S. terebinthifolius.
Palavras-chave: Produção de mudas florestais; micorriza; áreas degradadas.

Effect of the spatial and seasonal soil heterogeneity over arbuscular mycorrhizal fungal spore abundance in the semi-arid valley of Tehuacán-Cuicatlán, Mexico. Recent studies have shown that some species of Mimosa (Leguminosae-Mimosoideae) create resource islands (RI), rich in soil organic matter and nutrients, as well as in arbuscular mycorrhyzal fungal (AMF) spores, in the semi-arid Valley of Tehuacán-Cuicatlán. The relevance of this fact is that arid and semi-arid regions are characterized by low fertility soils and scarce precipitation, limiting plant species growth and development; this explains why the presence of AM fungi may be advantageous for mycorrhizal desert plants. Fluctuations in AMF spore numbers could be related to environmental, seasonal and soil factors which affect AMF sporulation, in addition to the life history of the host plant. The aim of this study was to asses the impact of spatial (resource islands vs open areas, OA) and seasonal (wet season vs start of dry season vs dry season) soil heterogeneity in the distribution and abundance of AMF spores in four different study sites within the Valley. We registered AMF spores in the 120 soil samples examined. Significant differences in the number of AMF spores were reported in the soil below the canopy of Mimosa species (RI) comparing with OA (RI > OA), and between Mimosa RI themselves when comparing along a soil gradient within the RI (soil near the trunk > soil below the middle of the canopy > soil in the margin of the canopy > OA); however, there were no significant differences between the soil closest to the trunk vs middle, and margin vs OA. Finally, more spores were reported in the soil collected during the wet season than during the dry season (wet > start of dry > dry). Therefore, the distribution of AMF spores is affected by spatial and seasonal soil heterogeneity. This study points out the relevance of Mimosa RI as AMF spore reservoirs and the potential importance of AM fungi for plant species survivorship and establishment in semi-arid regions. AM fungi have recently been recognized as an important factor determining plant species diversity in arid and temperate ecosystems. Rev. Biol. Trop. 53(3-4): 339-352. Epub 2005 Oct 3.

El abeto (Abies religiosa) es una especie forestal económica y ecológicamente importante para nuestro país. Desde tiempo atrás se le han dado múltiples usos y actualmente se reconoce su alto valor estético y ecológico. A la fecha, todavía no se cuenta con un programa para el manejo adecuado y completo de esta especie, principalmente por la falta de conocimiento sobre sus requerimientos ecológicos y las principales interacciones ecológicas que establecen estos árboles durante su ciclo de vida, como es el caso de la micorriza. Por lo tanto, en el INBIOTECA (Instituto de Biotecnología y Ecología Aplicada) es importante continuar generando el conocimiento que eventualmente permitirá plantear un mejor manejo de las poblaciones de oyamel, esperando que dicho esquema llegue a ser sostenible tanto en términos económicos como ecológicos.

The aim of the experiment was to study how Glomus mosseae influences the growth and flowering of cacti such as Mammillaria laui and Chamaecereus sylvestrii. The experimental theses have been: (1) soil inoculated with Glomus mosseae and fertilized; (2) soil without Glomus mosseae, irrigated with water and fertilizer (control). The test showed a significant increase in the agronomic parameters analysed in plants treated with Glomus mosseae. In fact, all cactus plants treated with endomycorriza showed a significant increase in the vegetative and radical part of the plants, in the number of flowers per plant and in the duration of flowering. This endomycorriza can therefore also have beneficial effects on plants that are slow to grow and prolong the life of their flowers, beautiful to see but that normally short-lived. Further studies will be done on the use of mycorrhiza on cacti and succulents and the influence on resistance to biotic and abiotic stress of different typologies.

Aim:  To evaluate the effects of soil physical and chemical factors (pH, conductivity, humidity, available phosphorus and organic matter) and environmental factors (temperature, relative air humidity, altitude and atmospheric pressure) on arbuscular mycorrhizal fungi (AMF)–Brachiaria decumbens grass relationship. Furthermore to establish patterns of microbiological responses that allow to differentiate the study sites in two relief types.Methods and Results:  Mycorrhizal characteristics (spore density, external hyphae and root colonizations by hyphae, vesicles and arbuscules), physical and chemical factors in soil and environmental factors were measured.Conclusions:  The effect of physical, chemical and environmental factors on microbiological variables was related to the type of relief ‘valley and hilly terrain’; the AMF behaviour was affected only over narrower ranges of evaluated variables. Similarly, the colonization of B. decumbens roots by AMF hyphae, vesicles and the mycorrhizal spore density follow different patterns according to the relief type.Significance and Impact of the Study:  The type of relief is one of the factors to be taken into consideration to evaluate the AMF inoculum and root colonization of these pastures, because of the influence of slope – as physical property of soil – on AMF.