Agronomic Management of Indigenous Mycorrhizas

Many of the advantages conferred to plants by arbuscular mycorrhiza (AM) are associated to the ability of AM plants to explore a greater volume of soil through the extraradical mycelium. Sieverding (1991) estimates that for each centimetre of colonized root there is an increase of 15 cm3 on the volume of soil explored, this value can increase to 200 cm3 depending on the circumstances. Due to the enhancement of the volume of soil explored and the ability of the extraradical mycelium to absorb and translocate nutrients to the plant, one of the most obvious and important advantages resulting from mycorrhization is the uptake of nutrients. Among of which the ones that have immobilized forms in soil, such as P, assume particular significance. Besides this, many other benefits are recognized for AM plants (Gupta et al, 2000): water stress alleviation (Augé, 2004; Cho et al, 2006), protection from root pathogens (Graham, 2001), tolerance to toxic heavy metals and phytoremediation (Audet and Charest, 2006; Göhre and Paszkowski, 2006), tolerance to adverse conditions such as very high or low temperature, high salinity (Sannazzaro et al, 2006), high or low pH (Yano and Takaki, 2005) or better performance during transplantation shock (Subhan et al, 1998). The extraradical hyphae also stabilize soil aggregates by both enmeshing soil particles (Miller e Jastrow, 1992) and producing a glycoprotein, golmalin, which may act as a glue-like substance to adhere soil particles together (Wright and Upadhyaya, 1998). Despite the ubiquous distribution of mycorrhizal fungi (Smith and Read, 2000) and only a relative specificity between host plants and fungal isolates (McGonigle and Fitter, 1990), the obligate nature of the symbiosis implies the establishment of a plant propagation system, either under greenhouse conditions or in vitro laboratory propagation. These techniques result in high inoculum production costs, which still remains a serious problem since they are not competitive with production costs of phosphorus fertilizer. Even if farmers understand the significance of sustainable agricultural systems, the reduction of phosphorus inputs by using AM fungal inocula alone cannot be justified except, perhaps, in the case of high value crops (Saioto and Marumoto, 2002). Nurseries, high income horticulture farmers and no-agricultural application such as rehabilitation of degraded or devegetated landscapes are examples of areas where the use of commercial inoculum is current. Another serious problem is quality of commercial available products concerning guarantee of phatogene free content, storage conditions, most effective application methods and what types to use. Besides the information provided by suppliers about its inoculum can be deceiving, as from the usually referred total counts, only a fraction may be effective for a particular plant or in specific soil conditions. Gianinazzi and Vosátka (2004) assume that progress should be made towards registration procedures that stimulate the development of the mycorrhizal industry. Some on-farm inoculum production and application methods have been studied, allowing farmers to produce locally adapted isolates and generate a taxonomically diverse inoculum (Mohandas et al, 2004; Douds et al, 2005). However the inocula produced this way are not readily processed for mechanical application to the fields, being an obstacle to the utilization in large scale agriculture, especially row crops, moreover it would represent an additional mechanical operation with the corresponding economic and soil compaction costs. It is well recognized that inoculation of AM fungi has a potential significance in not only sustainable crop production, but also environmental conservation. However, the status quo of inoculation is far from practical technology that can be widely used in the field. Together a further basic understanding of the biology and diversity of AM fungi is needed (Abbott at al, 1995; Saito and Marumoto, 2002). Advances in ecology during the past decade have led to a much more detailed understanding of the potential negative consequences of species introductions and the potential for negative ecological consequences of invasions by mycorrhizal fungi is poorly understood. Schwartz et al, (2006) recommend that a careful assessment documenting the need for inoculation, and the likelihood of success, should be conducted prior to inoculation because inoculations are not universally beneficial. Agricultural practices such as crop rotation, tillage, weed control and fertilizer apllication all produce changes in the chemical, physical and biological soil variables and affect the ecological niches available for occupancy by the soil biota, influencing in different ways the symbiosis performance and consequently the inoculum development, shaping changes and upset balance of native populations. The molecular biology tools developed in the latest years have been very important for our perception of these changes, ensuing awareness of management choice implications in AM development. In this context, for extensive farming systems and regarding environmental and economic costs, the identification of agronomic management practices that allow controlled manipulation of the fungal community and capitalization of AM mutualistic effect making use of local inoculum, seem to be a wise option for mycorrhiza promotion and development of sustainable crop production

Fertilization with beneficial microorganisms decreases tomato defenses against insect pests

International audienceThe adverse effects of chemical fertilizers on agricultural fields and the environment are compelling society to move toward more sustainable farming techniques. “Effective microorganisms” is a beneficial microbial mixture that has been developed to improve soil quality and crop yield while simultaneously dramatically reducing organic chemical application. Additional indirect benefits of beneficial microorganisms application may include increased plant resistance to herbivore attack, though this has never been tested till now. Tomato plants were grown in controlled greenhouse conditions in a full-factorial design with beneficial microorganisms inoculation and commercial chemical fertilizer application as main factors. We measured plant yield and growth parameters, as well as resistance against the generalist pest Spodoptera littoralis moth larval attack. Additionally, we measured plant defensive chemistry to underpin resistance mechanisms. Overall, we found that, comparable to chemical fertilizer, beneficial microorganisms increased plant growth fruit production by 35 and 61 %, respectively. Contrary to expectations, plants inoculated with beneficial microorganisms sustained 25 % higher insect survival and larvae were in average 41 % heavier than on unfertilized plants. We explain these results by showing that beneficial microorganism-inoculated plants were impaired in the induction of the toxic glycoalkaloid molecule tomatine and the defense-related phytohormone jasmonic acid after herbivore attack. For the first time, we therefore show that biofertilizer application might endure unintended, pest-mediated negative effects, and we thus suggest that biofertilizer companies should incorporate protection attributes in their studies prior to commercialization

Anales de Edafología y Agrobiología Tomo 34 Número 3-4

Estudio de la materia orgánica del ranker atlántico. I. Caracterización general, por P. Rodríguez Seoane, T. Carballas y F. Guitián Ojea.-- Movimiento y distribución de sales solubles en suelos calizos, por F. G. Fernández, M. Caro y A. Cerda.-- The availability of added and native phosphorus to barley grown in sorne Egyptian soils .containing different levels of calciurn carbonate, by M. H. Nafady.-- The measurernent of soil pH in calciurn chloride solutions, by M. H. Nafady.- Nuevas aportaciones al conocimiento del género Mnema (nernatoda) y su distribución en los suelos españoles, por María Arias.-- Estudios bioquímicos y fisiológicos en aceituna. III. Variaciones en el crecimiento de hojas y frutos, por J. P. Donaire, A. J. Sánchez-Raya, J. López Corge y L. Recalde.-- Importancia de la rnicorrización espontánea en ensayos de nutrición vegetal en suelos deficientes en fósforo, por R. Azcón y J. M. Barea.-- Andosoles canarios. J. Características generales de estos suelos, por E. Fernández Caldas y M. L. Tejedor Salguero.-- Andosoles canarios. II. Intergrados andosol-tierra parda oligotrófica. Características morfológicas y quírnkas, por M. L. Tejedor Salguero y E. Fernández Caldas.-- Andosoles canarios. lll. Jntergrados andosol-tierra parda otigotrófica. Catacterísticas físicas, por E. Fernández Caldas y M. L. Tejedor Salguero.-- Andosoles canario;. IV. In ter grados andosol-tierra parda ohgotrófica. Características mineralógicas. Interpretación y clasificación, por C. Rodríguez Pascual, P. Quantin, M. L. Tejedor Salguero y E. Fernández Caldas.-- Estudios recapitualtivos.-- La vid una revisión de las condiciones del cultivo, por C. González O. y M. Lachica.—Notas científicas.-- Nota sobre la determinación del carbono orgánico en suelos, por J. F. Gallardo.—Notas.-- Ampliación de la Comisión Permanente de la Junta de Gobierno del Patronato Alonso de Herrera.-- Nombramiento de Secretario del Centro de Edafología y Biología Aplicada de Tenerife.-- Nombramientos en el Instituto de Alimentación v Productividad Animal.-- Cambio de representantes del Patronato Alonso de Herrera en la Comisión Asesora de la Investigación Científica y Técnica.-- Convenio con ASPA.-- Dimisión del Director del Centro de Edafología y Biología Aplicada del Segura de Murcia.-- Nombramientos de representantes en los C. R. l. D. A. S.-- Designación de Jurados para Premios del C. S. l. C.-- Informes del Secretario Adjunto del C. S. I. C. sobre reuniones en Europa.-- Convenio entre la Estación Experimental del Zaidín y la Universidad de Nápoles.-- Donación de terrenos a la Diputación de Badajoz.-- Seminario Oleícola Internacional.-- Congreso de la Unión Fitopatológica Mediterránea.-- Situaciones de personal.-- Reunión de la Comisión de Protección Vegetal.-- Día Forestal Mundial.-- Congresos y reuniones internacionales y viajes.-- Premio Agrícola Aedos.-- BibliografíaPeer reviewed2019-08.- CopyBook.- Libnova.- Biblioteca ICA

Anales de Edafología y Agrobiología Tomo 33 Número 9-10

Estudio del equilibrio nutritivo en cultivos de chirimoyo (Annona cherimolia), por César González O., Miguel Fuentes y Soledad Díaz.-- Resistencia a la desecación del tejido foliar y cierre de estomas en alfalfa (M edicago sativa L.) y trébol blanco (Trijolium repens L.) con relación al déficit agua, por M. Sánchez-Díaz y M. Sánchez-Marín.-- Determinación del calor isostérico y consideraciones sobre el mecanismo de la adsorción de fosfato por óxidos de hierro, por L. Madrid, F. Cabrera, P. de Arambarri y E. Díaz.-- Studies on sodium-calcium exchange equilibria. II. In Egyptian soils, by M. H. Nafady.-- Indices nutritivos en manzano (var. R. Delicious), por C. González, O. M. Rodríguez M., J. Solé D. y A. Wylie W.-- Caracteres de los suelos de las zonas citrícolas del valle de Murcia (España), por J. A. Sánchez F., F. Artes y J. López-Tarruella.-- Estudio micromorfológico de suelos desarrollados sobre andesitas en Andalucía oriental, por J. Aguilar y M. Delgado.-- Estudio edafológico de los relieves próximos a la vega de Motril, por J. Aguilar, Ruiz, A. Monge Ureña y C. Sierra Ruiz de la F.-- Consideraciones experimentales sobre el análisis de boro en plantas, por A. León, F.J. López-Andréu, F. Romojaro y C. Alcaraz.-- Efectos de la aplicación conjunta de fertilizantes químicos y microbianos (Azotobaeter Fosjobaeterias) en cultivos enarenados de tomate, por R. Azcón, M. Gómez y J. M. Barea.-- Formas de calcio en suelos del piso tropical de Barbacoas, Colombia, por G. Hugo Eraso, L. Federman Ortiz y O. Hernán Burbano.-- Compuestos íenólicos en Eriea vagans L., por J. Arinés, J. L. G. Mantilla y E. Vieitiz.-- Determinación de glúcidos en plantas por fotocolorimetría. Estudio comparativo de métodos clásicos y automáticos, por C. Cadahía y M. T. Piñeiro.-- Notas. Nombramiento de Consejeros Adjuntos del Patronato Alonso de Herrera.-- Nombramiento y cese de Vocales de la Junta de Gobierno del Patronato Alonso de Herrera.--Fallo de los Premios Alonso de Herrera y Antonio José de Cavanilles.-- Propuesta del Instituto de Alimentación y Productividad Animal sobre nombramiento de Vicedirector del mismo.-- Congresos y Reuniones internacionales.-- Creación de la Comisión Conjunta de Investigación Agraria de los Ministerios de Educación y Ciencia y de Agricultura.-- Restauración y adecuación del Jardín Botánico de Madrid.-- III Reunión Nacional de Centros de Investigación Ganadera Tribunales.-- Clausura del XI Curso Internacional de Edafología y Biología Vegetal.-- 7th International Colloquium on Plant Analysis and Fertilizer Problems.-- X Congreso Internacional de Ciencia del Suelo.-- Clausura del IV Congreso de Ciencia y Tecnología de Alimentos.-- 50th Anniversary Meeting of the British Society for Experimental Biología.-- XXIX Symposium on Symbiosis, Society for Experimental Biología.-- IV Reunión de la Sociedad Español de Microscopía Electrónica.-- Subvención de la Fundación Barrie de la Maza a la Misión Biológica de Galicia.-- Conferencia.-- Los universitarios y la defensa de la naturaleza.-- Seminario, sobre Tipos diferentes de costras calizas y su distribución regional.-- BibliografíaPeer reviewed2019-08.- CopyBook.- Libnova.- Biblioteca ICA

Unique arbuscular mycorrhizal fungal communities uncovered in date palm plantations and surrounding desert habitats of Southern Arabia

The main objective of this study was to shed light on the previously unknown arbuscular mycorrhizal fungal (AMF) communities in Southern Arabia. We explored AMF communities in two date palm (Phoenix dactylifera) plantations and the natural vegetation of their surrounding arid habitats. The plantations were managed traditionally in an oasis and according to conventional guidelines at an experimental station. Based on spore morphotyping, the AMF communities under the date palms appeared to be quite diverse at both plantations and more similar to each other than to the communities under the ruderal plant, Polygala erioptera, growing at the experimental station on the dry strip between the palm trees, and to the communities uncovered under the native vegetation (Zygophyllum hamiense, Salvadora persica, Prosopis cineraria, inter-plant area) of adjacent undisturbed arid habitat. AMF spore abundance and species richness were higher under date palms than under the ruderal and native plants. Sampling in a remote sand dune area under Heliotropium kotschyi yielded only two AMF morphospecies and only after trap culturing. Overall, 25 AMF morphospecies were detected encompassing all study habitats. Eighteen belonged to the genus Glomus including four undescribed species. Glomus sinuosum, a species typically found in undisturbed habitats, was the most frequently occurring morphospecies under the date palms. Using molecular tools, it was also found as a phylogenetic taxon associated with date palm roots. These roots were associated with nine phylogenetic taxa, among them eight from Glomus group A, but the majority could not be assigned to known morphospecies or to environmental sequences in public databases. Some phylogenetic taxa seemed to be site specific. Despite the use of group-specific primers and efficient trapping systems with a bait plant consortium, surprisingly, two of the globally most frequently found species, Glomus intraradices and Glomus mosseae, were not detected neither as phylogenetic taxa in the date palm roots nor as spores under the date palms, the intermediate ruderal plant, or the surrounding natural vegetation. The results highlight the uniqueness of AMF communities inhabiting these diverse habitats exposed to the harsh climatic conditions of Southern Arabia

Characterization of arbuscular mycorrhizal fungus communities of Aquilaria crassna and Tectona grandis roots and soils in Thailand plantations

Aquilaria crassna Pierre ex Lec. and Tectona grandis Linn.f. are sources of resin-suffused agarwood and teak timber, respectively. This study investigated arbuscular mycorrhizal (AM) fungus community structure in roots and rhizosphere soils of A. crassna and T. grandis from plantations in Thailand to understand whether AM fungal communities present in roots and rhizosphere soils vary with host plant species and study sites. Terminal restriction fragment length polymorphism complemented with clone libraries revealed that AM fungal community composition in A. crassna and T. grandis were similar. A total of 38 distinct terminal restriction fragments (TRFs) were found, 31 of which were shared between A. crassna and T. grandis. AM fungal communities in T. grandis samples from different sites were similar, as were those in A. crassna. The estimated average minimum numbers of AM fungal taxa per sample in roots and soils of T. grandis were at least 1.89 vs. 2.55, respectively, and those of A. crassna were 2.85 vs. 2.33 respectively. The TRFs were attributed to Claroideoglomeraceae, Diversisporaceae, Gigasporaceae and Glomeraceae. The Glomeraceae were found to be common in all study sites. Specific AM taxa in roots and soils of T. grandis and A. crassna were not affected by host plant species and sample source (root vs. soil) but affected by collecting site. Future inoculum production and utilization efforts can be directed toward the identified symbiotic associates of these valuable tree species to enhance reforestation efforts