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Background and aims: The plant's roots and fungi establish symbiotic endophytic associations that can coexist: arbuscular mycorrhizae and "dark septate" endophytes. Ferns and lycophytes are vascular plants that can form both fungal symbioses. The objective of this work is to detect the presence of fungal root endosymbiosis, know the mycorrhizal status, and analyze the type of colonizationin in native and ornamental ferns from the "Sierras Centrales de San Luis". M&M: In three sites in the "Sierras Centrales de San Luis", 9-10 individuals of each studied species were collected, their roots were processed to study these fungal. Characterization and quantification of their root colonization was evaluated. Results: In the three sites studied, Anemia tomentosa var. anthriscifolia formed mycorrhizal associations, the colonization presented abundant hyphal and arbusculated intracellular coils. In addition, glomoid spores of mycorrhizal fungi were found in their rhizospheres. Dark septate endophytes were absent in all species analyzed, none hyphae neither microsclerotia were recorded in roots of these native medicinal ferns. Conclusions: The mycorrhizal status of Anemia tomentosa var. anthriscifolia, one of the five medicinal fern species from the Sierras Centrales de San Luis studied, is presented. The arbuscular mycorrhizal colonization is described and quantified, and its type is determined as Paris. None of the fern species studied was associated with dark septate endophytes. [ABSTRACT FROM AUTHOR]

The research was carried out at the "Los Palacios" Urban Farm, belonging to the Cubaquivir Agroindustrial Company where a Ferrallitic Yellowish Leach Petroferric soil predominates with the aim of evaluating the effect of the biofertilizer EcoMic® application in the cultivation of the bean cv. Canton in two different production systems. Biofertilizers was applied at a dose of 10 % based on the seed mass before sowing by the coating method. In the intensive production area two plots of 0.25 ha were planted. One with seed treated with the biofertilizer (MA) and the other untreated (noMA) and in the organoponic two beds of 10 m long x 1.20 m Wide. The percentage of mycorrhizal colonization, plant height, number of pods per plant, pod length, number of seeds per pod and agricultural yield were evaluated in both treatments and production systems. It was obtained as a result that in the treatments with EcoMic®, the plant height increased, the number of pods per plant, the length of the pods, the number of seeds per pod and the agricultural seed yield between 15 and 23 %. The greatest increases in the growth and development of bean plants were obtained under organoponic conditions. [ABSTRACT FROM AUTHOR]

Bioestimulants contribute to increase yield reflected in fruits. In this sense, a study was carried out at the Institute of Tecomatlan, Puebla, Mexico, to evaluate the influence of the Quitomax® use and the inoculation with two strains of mycorrhizae in the behavior of some variables of fruit. Seedlings were produced in trays with a commercial substrate, under the same treatments that would later be applied in field conditions, which consisted of a control where seeds were soaked in water three hours, the same time and application form, when mycorrhizae were used, and Quitomax solution. The two mycorrhizal inoculants were applied by coating the seeds. Six treatments were established since both bioestimulants were also used in combination. A randomized block design was used in the field whit four replications. At transplantation time, each inoculum was applied at root system and Quitomax® was sprayed on the foliage at seven and 28 days. The quantity of fruits per plant was evaluated and in the sixth harvest, 30 fruits were taken at random per replication of each treatments, from which the equatorial and polar diameter were measured. Treatments caused variations in the distribution of fruits by size and in the equatorial diameter, but not in the fruit shape. The number of fruits increased with respect to the control, but not their mass to the same extent. [ABSTRACT FROM AUTHOR]

The objective of the research was to determine the effect of biochar enriched with worm humus and arbuscular mycorrhizal fungi (AMF) on growth and galling of yam plants and M. incognita reproduction. The study was developed under semi-controlled conditions in a biological isolator of the Instituto de Investigaciones de Viandas Tropicales (INIVIT), Santo Domingo, Villa Clara Province, Cuba, in 2022. A completely randomized design with seven replicates was used. The treatments consisted of different combinations of soil, biofertilizers, and biochar, with and without inoculation of a pure population of M. incognita established at the institute. The best development of yam plants was obtained in the treatment where, in the absence of M. incognita, the plants were grown in a substrate containing a mixture of biochar + humus and mycorrhizae as inoculant. It was evident that M. inognita parasitism affected the development of the cultivar 'INIVIT Ñ-2008' because of the decreases produced in plant stem length and fresh and dry matter of the foliar part. The potentialities of incorporating AMF, humus, and biochar in the production technology of D. alata were evidenced by the positive effects on plant growth and development and reduction of M. inognita galling index and reproduction on this cultivar, which was cataloged as a good host and susceptible to this nematode; results which will be corroborated in subsequent field studies. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ciencia y Tecnología Agropecuaria is the property of Agrosavia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

La necesidad de buscar alternativas para mejorar la nutrición de los cultivos ante la baja fertilidad de los suelos agrícolas y la escasez de fertilizantes, cobra cada día mayor importancia. Una de estas alternativas es la aplicación de abonos orgánicos y la inoculación con hongos micorrízicos arbusculares (HMA). El objetivo del presente trabajo fue investigar el efecto de las aplicaciones de vermicompost y la inoculación de un biofertilizante micorrízico sobre el suministro de nutrientes de un suelo Gley Nodular Ferruginoso para plantas de millo perla (Panicum italicum L.). Se ejecutaron dos experimentos en condiciones de mesocosmos en el Instituto Nacional de Ciencias Agrícolas (INCA), se estudiaron cuatro proporciones de suelo-vermicompost, con y sin la inoculación micorrízica, en un diseño completamente aleatorizado con estructura factorial y tres repeticiones. Se evaluaron la altura, la masa seca de la biomasa aérea y la concentración y cantidad de nutrientes en las plantas, la frecuencia e intensidad de la colonización y el número de esporas en el suelo. La aplicación de vermicompost incrementó la disponibilidad de nutrientes del suelo y se reflejó en el incremento de la concentración y la cantidad de nutrientes en las plantas, lo que originó mayor crecimiento y desarrollo de estas; en presencia del millo perla la aplicación de vermicompost hizo disminuir la frecuencia e intensidad de la micorrización, lo que inhibió el efecto de la inoculación con hongos micorrízicos arbusculares y no se afectó la producción de esporas en el suelo. [ABSTRACT FROM AUTHOR]

Los hongos micorrizógenos arbusculares (HMA) establecen simbiosis con la mayoría de las plantas. Los mismos producen y liberan al suelo una glicoproteína denominada glomalina favoreciendo la formación de agregados estables en agua y mejoran la estructura de los suelos. El objetivo del presente trabajo fue caracterizar varios suelos Ferralíticos Rojos de la Llanura Roja de La Habana, con diferente uso, mediante algunas propiedades químicas (materia orgánica, pH, P, Ca, C, N) y biológicas, así como establecer correlaciones entre ambos tipos de variables. Las variables biológicas fueron el número de esporas de HMA y los contenidos de proteínas del suelo relacionadas a glomalina (total y fácilmente extraíble). Para esto se utilizaron diferentes métodos extractivos, seguido de la estimación de la concentración de proteínas o del conteo de esporas totales. Los resultados revelaron diferencias en las variables determinadas relacionadas a los cultivos presentes y al manejo del suelo. En general, los bosques mostraron valores superiores en las fracciones de glomalina, seguidos por los cultivos de caña (Saccharum officinarum) y pasto, mientras que los valores inferiores correspondieron a los suelos cultivados con papa (Solanum tuberosum), constituyendo estas variables mejores indicadores de la calidad del suelo que el número de esporas de HMA, dada su correlación con algunas variables químicas del suelo como la materia orgánica, C, N, pH y Ca. Se sugieren investigaciones futuras para dilucidar los resultados obtenidos, principalmente en cuanto al uso de la glomalina como indicador biológico de la degradación/ rehabilitación de los suelos según el ecosistema en estudio. [ABSTRACT FROM AUTHOR]

Podocarpacea are the only native conifers of Peru, a country that contains one of the most important South American populations of one of its member species: Retrophyllum rospigliossi Pilger, which lives in the rainforests, where it is only preserved In small relics; due to this and the difficulties for reproduction and conservation in-situ is considered a vulnerable species. Among the microorganisms of the soil, the mycorrhizal fungi stand out for their symbiotic activity by allowing efficient nutrition, being beneficial for many species of trees, providing them with the necessary conditions for their survival. The objective of this work was to characterize the mycorrhizal colonization of Retrophyllum rospigliossi Pilger in the categories of saplings, latizal and fustal, and for this purpose, samples were collected in five georeferenced plots. The roots were colored with trypane blue for the observation of hyphae, vesicles, and shrubs. Soil samples were sifted for spore count. Mycorrhizal structures were found in all three categories, with significant differences for spores and vesicles. The behavior of these per gram of soil was variable (hyphae: 39.2% to 53%, spores 30.8% to 57.6 °/o, vesicles: 35% to 51.4 °/o, shrubs: 0 to 2%). Colonization of roots ranged from 85% to 96.2%. Three mycorrhizal genera were identified: Glomus, Entrophospora and Acaulospora. It is concluded that, for a vegetative propagation of woody species, it is necessary to consider the use of arbuscular mycorrhizae to guarantee an adequate nutrition. [ABSTRACT FROM AUTHOR]

Se realizó un experimento con el objetivo de evaluar el efecto de la biofertilización con la rizobacteria Azospirillum brasilense y el hongo micorrízico arbuscular Rhizoglomus irregulare en el pasto Brachiaria híbrido cv. Mulato II cultivado en un suelo Pardo Mullido Carbonatado. Se incluyeron cuatro tratamientos conformados por la inoculación sola y combinada, de ambos microorganismos, más un testigo sin inocular, en un diseño cuadrado latino. El inóculo con R. irregulare poseía una concentración de 30 esporas g-1 y se aplicó mediante el método del recubrimiento de las semillas al momento de la siembra, mientras que A. brasilense, con una concentración de 109 UFC mL-1, se aplicó sumergiendo las semillas en una solución de inóculo y agua en relación 1:10, y a razón de 20 L ha¹ después del primer corte. Se realizaron cuatro cortes, a intervalos de 60 y 90 días en el período lluvioso y poco lluvioso, respectivamente. R. irregulare aumentó la frecuencia e intensidad de la colonización micorrízica, así como el número de esporas en la rizosfera, aunque los mayores resultados se alcanzaron cuando se aplicó con A. brasilense. Los biofertilizantes por separado incrementaron el crecimiento de la parte aérea y radical de las plantas, las concentraciones de nitrógeno en la biomasa aérea y el rendimiento de masa seca del pasto, pero los mayores valores de estas variables, así como la mayor contribución de la biofertilización a la nutrición nitrogenada del pasto, se obtuvieron con su aplicación conjunta. El efecto de la biofertilización se mantuvo durante un año. [ABSTRACT FROM AUTHOR]

Grazing by large herbivores represents an important disturbance in natural grasslands, affecting its structure and function. Arbuscular mycorrhizas (AM) are cosmopolitan interactions in these ecosystems, particularly in grasses, main constituent of this ecosystem. Mycorrhizas show contradictory responses to grazing (AM colonization has been positively, negatively and not affected by grazing). We hypothesized that each grazing component (selective defoliation, trampling and urine deposition) would differentially affect mycorrhizal colonization, and this could explain the high variability in AM responses. Our objective was to assess the effect of trampling, selective defoliation and nitrogen (N) addition on AM colonization of one of the most important grasses in Río de la Plata grasslands: Paspalum dilatatum. Grazing components were simulated in a manipulative experiment where we evaluated their individual and combined effects on total AM colonization and the occurrence of different fungal structures (arbuscules, coils and vesicles). No grazing component affected total AM colonization and arbuscules, while other fungi structures were affected by different treatments. Coil colonization (one of the nutrient interchange structures between the symbionts) was positively affected by selective defoliation and it was negatively affected by N addition; these structures were also affected by the combined effect between selectivity x trampling and by trampling x N addition. Vesicle colonization was negatively affected by trampling, maybe because of mechanical damage to roots and to extraradical mycelium caused by this disturb. The study of the individual grazing components showed that each one caused different effects on mycorrhizal interaction and their relative influence could affect the overall grazing effect on this interaction. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The conversion of high-input agriculture to an agro-ecological approach bring harmony to the environment reducing degraded Agroecosystems. The objective of this study was to evaluate the effect of different nutritional management on yield and internal and external quality of tomato fruits as an alternative to the reduction of mineral fertilizers. The research was carried out at the National Institute of Agricultural Sciences (INCA) in Cuba, from September 15 to November 30, 2016. A randomized block design with four replications was used to study four treatments: Absolute control (without mineral fertilizer and bioproducts), Partial ecological nutrition (50 % of mineral fertilizer + bioproducts: mycorrhiza and biostimulant), Organic nutrition (organic fertilizer + bioproducts: mycorrhiza and biostimulant), and Conventional nutrition (NPK mineral fertilizer only). Evaluations regarding agricultural yield and its components, bromatological quality of fruits (brix, acidity, vitamin C content, and nitrates) and postharvest indeces (fruit firmness and diameter of endocarp and mesocarp) were performed. Agricultural yield (25.31 t/ha) and the internal quality of fruits (5.23 °Brix; 11.75 SST; 73.29 nitrates; 18.54 vitamin C, and 4.45 dry matter) applying the treatment where 50% of mineral fertilization was dispensed andcomplemented by bioproducts did not show significant differences with NPK treatment. Regarding the organic variant, the result in agricultural yield was lower (19.42 t/ha), in comparison with control and the ecological variant. Therefore, it is suggested further evaluation of the effect of the reduction of mineral fertilization on tomato crop and its combination with bioproducts. [ABSTRACT FROM AUTHOR]

Microbial interactions: effect of biocontrol and P solubilizing fungi in pre-symbiotic stages of arbuscular mycorrhizal fungi. Phosphorus (P) is an essential macronutrient with a low bioavailability in soils, thus limiting the plant growth. The use of P solubilizing fungi (HS) is a promising alternative to increase the efficiency of P-fertilizers. However, it is not fully understood if HS have antagonist effects on beneficial soil microbiota, such as arbuscular mycorrhizal fungi (HMA). This work studies the effect of HS with biocontrol abilities against phytopathogenic fungi on the pre-infective stages development of HMA, the first step in mycorrhizal root colonization. Spores of the HMA Gigaspora rosea were exposed in vitro to different exudate concentrations (0; 0,01; 0,1; 1; 3%) of different HS fungal strains (Talaromyces helicus strain L7B, T. helicus strain N24, T. diversus and Penicillium purpurogenum) in a system containing semi-liquid medium. Spores germination, elongation, ramification and morphology of the pre-infective mycelium of HMA were evaluated. We observed that only T. diversus increased germination while T. helicus L7B promoted the elongation, ramification and produced changes in the mycelial morphology without affecting spores' germination. These results showed that germination and pre-infective development of G. rosea can be modified in length and ramification as a function of the identity of the HS strain used, suggesting that microbial interactions can positively impact on plant P nutrition through the modification of the previous stage to mycorrhizal symbiosis. [ABSTRACT FROM AUTHOR]

In Cuba, it have been carried out investigations related with the inoculation of species of arbuscular mycorrhizal fungis (AMF) in diverse crops and soil types, being that, for a same soil type, the species that bigger stimulation of the growth of the host plant is always the same, what has allowed infering that a high specificity efficient species of AMF exists for soil type. This work was carried out to evaluate if some properties of the soil have relationship to the response of Canavalia ensiformis to the AMF inoculation, cultivated in three types of soils. They were used the results of experiments conduced in Nitisol, Cambisol and Plintosol soils. The canavalia was inoculated with the species Glomus cubense, Rhizophagus intraradices and Funneliformis mosseae. In all the cases was used at complete randomized blocks design. The results of the behavior of the canavalia inoculated with the most efficient species and the chemical properties of the soil were processed by means of a correlation analysis through the coefficient of Pearson. Also, it was carried out an analysis of main components for all the valued indicators. It is demonstrated that the soil type, their nutrients content and the pH have a high relationship with the answer type found in canavalia, being therefore, the efficient specie that was different in each case, in correspondence with the chemical properties of the soil in each analyzed experimental situation. [ABSTRACT FROM AUTHOR]

Indiscriminate use of chemical fertilizers in the cultivation of garlic (Allium sativum L.) makes his productions unsustainable especially from the ecological point of view, hence the importance of implementing viable alternatives in their nutrition. An experimental plot was set up in areas of the farm "Los Pérez" Credit and Service Strengthened Cooperative (CCSS) "Niceto Pérez García" Las Tunas municipality, between 2011 and 2014. A design of random blocks with four treatments and six replicates was used. The treatments consisted of single and combined use of EcoMic® and Fitomas E® and a control without application. The effect of these treatments in some morphological parameters and performance (pseudostem diameter, mass of bulbs, bulbs diameter, number of cloves by bulb, mass and width of the cloves and determined performance in t ha-1). The data were subjected to analysis of variance dual classification and comparison of means. The application of all the alternatives showed positive results in the studied parameters compared to a control without fertilization at showing the feasibility of its use in the conditions of climate and soil in the center of Las Tunas province and contributes to the sustainability of these agroecosystems. [ABSTRACT FROM AUTHOR]

Considering the existence of arbuscular mycorrhizal inoculants applied at low quantities to cassava crop (Manihot esculenta Crantz) and the high mycorrhizal dependence as well as the significance of this crop in Angola, it is essential to evaluate the effectiveness of such products in this country, as a way to obtain an efficient mycorrhizal symbiosis and its benefits on cassava plantations. An experiment was conducted on a Rhodic Distric Ferralsol, in order to appraise the effect of Funneliformis mosseae strain INCAM-2 compared with a control treatment, in a randomized block design with four repetitions and 32 plants per plot. The trial was carried out in a Kibala producers' farm, South Kwanza province, using Calohendo variety. The inoculant was applied at planting time by coating both propagule tips at the dose of 11,6 kg ha-1. The application of F. mosseae provided significant increases (P<0,001) in every variable tested, achieving more vigorous and taller plants, their height raising about 21%, whereas edible root yields rose from 14,4 mg ha-1 in the control to 33,6 mg ha-1 in the inoculated treatment and mycorrhizal spores improved eight times at harvest time, indicating the effectiveness of F. mosseae under these edaphic conditions. These results prove the potentiality of applying such mycorrhizal products to cassava crop in Angola. [ABSTRACT FROM AUTHOR]

A study was conducted in order to evaluate the cutting intervals (30, 60 and 90 days) and the nutrition management in mulberry: without mineral fertilizers or intercropped and AMFinoculated Canavalia ensiformis (F0); mineral fertilization at a rate of 150 and 75 kg ha-1 of N and K2O per season (MF), respectively; and intercropped and AMF-inoculated C. ensiformis (CeAMF). The design was randomized blocks with factorial arrangement, and the soil is classified as lixiviated Ferralitic Red. In the rainy season, the highest yields were obtained with CeAMF and cutting every 90 days (between 10,99 and 6,85 kg DM ha-1), and in the dry season this indicator was higher in MF (between 3,56 and 2,52 kg DM ha-1). The edible biomass production per cutting at 90 days showed differences among treatments in favor of MF in the first cutting and of CeAMF in the second cutting. CeAMF with the 90-day interval reached a proportion of leaves higher than the population mean in the rainy season, unlike the dry season. The CP yield in the rainy season was higher in MF with the 60- and 90-day intervals, and in CeAMF in the 90-day interval. It is concluded that the cutting interval every 90 days was the best, and that it was feasible to intercrop AMF-inoculated C. ensiformis in the rainy season. The season determined the amount of forage and crude protein production, which was three times higher in the rainy season. [ABSTRACT FROM AUTHOR]

Plants live in environments where they are exposed to multiple stress factors that cause alterations in their normal physiology. However, the evidence suggests that mutualistic relationships with microbes can help plants to overcome the detrimental effects of some abiotic stress factors. The goal of this research was to investigate the individual and interactive effects of solar ultraviolet (UV) radiation (280- 400 nm) and arbuscular mycorrhizal (AM) symbiosis on vegetative growth in seedlings of three shade intolerant species. Seedlings of Populus deltoides, Betula nigra, and Salix nigra were grown in greenhouse under a 2 X 2 factorial design, with two UV radiation conditions (with and without UV radiation) and two AM treatments (with normal AM inoculum or with autoclaved inoculum). After three months, plants were harvested and growth, morphology, and allocation variables were measured, percentage of roots colonized by AM fungi was assessed using the grid line intercept technique. The results showed that seedlings exposed to UV radiation had smaller root masses, stem diameters, and root to shoot ratios; and greater specific leaf areas and leaf area ratios. Mycorrhizal colonization did not result in any increase in growth, and in one case the AM plants were smaller than the non-mycorrhizal control. Ultraviolet radiation reduced the percentage of root colonized by AM fungi of P. deltoides and S. nigra. The results demonstrate that ambient levels of UV radiation can exert an indirect effect on mycorrhizal fungi in the rhizosphere of tree seedlings. [ABSTRACT FROM AUTHOR]

Se evaluó el efecto de la coinoculación de tres cepas de rizobio, y una del hongo micorrízico arbuscular (HMA) en Stylosanthes guianensis vc. CIAT-184. El experimento se realizó en la Estación de Pastos y Forrajes de Cascajal, en la provincia Villa Clara, en un suelo Gley Nodular ferruginoso. Se estudiaron ocho tratamientos: las cepas de rizobios S1, S2 y S3, solas y combinadas con la especie de HMA Funneliformes mosseae, un testigo con F. mosseae sin rizobio, y otro sin rizobio ni F. mosseae. Los tratamientos se distribuyeron en un diseño de bloques al azar, con cuatro repeticiones. Se presentan los resultados de los dos primeros cortes. Las cepas S2 y S3 incrementaron significativamente la nodulación (31-40 nódulos/planta) y la concentración de nitrógeno en la biomasa aérea (3.55-4.00%), con respecto a S1 y los tratamientos testigo. F. mosseae incrementó los porcentajes de frecuencia e intensidad de colonización y densidad de esporas en la rizosfera, así como las concentraciones de P en la biomasa aérea (0.25 %). La coinoculación de ambos microorganismos mejoró la efectividad de la nodulación e incrementó las estructuras micorrízicas y el rendimiento del estilosante. Se obtuvieron los mejores resultados con las cepas S2 y S3 en presencia de F. mosseae. Se comprobó, en las condiciones de este estudio, el efecto sinérgico de las bacterias nitrofijadoras y los hongos micorrízicos arbusculares, así como las ventajas de la coinoculación de ambos microorganismos para mejorar el rendimiento y el valor nutritivo del estilosante, al menos durante su establecimiento. [ABSTRACT FROM AUTHOR]

Copyright of Revista Luna Azul is the property of Universidad de Caldas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to evaluate the influence of inoculation with arbuscular mycorrhizal fungi (AMF), the period of synchrony between the incorporation of green manure and planting Canavalia ensiformis and fertilization doses on maize growth, was conducted this work, which developed in microplots conditions, repeated for two years, in the period between the months of August to October of 2003 and 2004, in areas of the National Institute of Agricultural Sciences (INCA) of Cuba, in a Rhodic Nitisol soil. We studied three doses of mineral nitrogen fertilizer (0, 40 and 80 kg ha-1 of N), two periods of synchrony between incorporating canavalia and planting the main crop (7 and 21 days) and two levels of mycorrhizal inoculation corn factor (with and without inoculation) in a completely randomized design under trifactorial arrangement (3x2x2) and three reference controls. There was interaction between the factors under study, finding that the combined use of mycorrhizal inoculation of corn and canavalia is also diminishing doses of mineral fertilizer needed for the crop to reach a dry mass and nutrient content similar to those obtained with the high dose of nitrogen fertilizer studied. Mycorrhizal colonization was found in all the treatments, but the most significant values were found in treatments with AMF inoculation and application of two nitrogen sources. The sync time of seven days resulted the optimum in the conditions of this study. [ABSTRACT FROM AUTHOR]

Research was conducted in the Greenhouse section of the Central Experimental Research Support (SCSIE), University of Valencia, Spain. We used the tomato (Solanum lycopersicum L. cultivar 'Amalia') as a model crop whose seeds were disinfected prior to planting. Substrate a mixture of organic substrate and vermiculite (1:1) was used. Crop grown under controlled conditions of temperature and relative humidity. Glomus cubense was studied and it was inoculated into seed stage at 250 esporas/mL of water in a final volume of 800 mL. The inoculation was performed once during experiment cycle. At 15 days of cultivation positions germinated were transplanted to pots containing organic substrate conical, vermiculite, and silica sand (1:2:1). Two treatments were studied following a completely randomized design: uninoculated control and inoculated to a total of 30 pots for each treatment. Evaluations were performed every 15 days until the flowering stage of cultivation and development indicators were evaluated vegetative and mycorrhizal functioning. Results showed capillary AMF inoculation in tomato plants under was effective as indicators studied by controlled conditions. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the fungal species forming arbuscular mycorrhizal (AM) inhabiting in traditional agroforestry systems with cacao (Theobroma cacao L.). Five agroecosystems located in farms from the humid tropics in Ecuadorian central region were sampled, particularly the farms 'La Represa', 'La Propiedad', 'La Union', 'Fatima' and 'Mi Recuerdo' located in Quevedo and Valencia cantons of Los Rios province. Soil and root samples were collected during the dry season between June and December of 2009. The fungi genera found were: Gigaspora, Acaulospora, Glomus and Scutellospora. In all sites sampled, Glomus was the most representative genus in terms of amount of spores found per gram of soil, while Gigaspora was the genus of which fewer spores were found. The percentage of existing level of mycorrhizal colonization in T. cacao was also assessed, with the highest percentage found in samples collected from farms 'Mi Recuerdo' and 'La Union', whilst the lowest percentage was found in the roots of T. cocoa collected from 'La Propiedad' farm. [ABSTRACT FROM AUTHOR]

To evaluate the influence of the number of spores of arbuscular mycorrhizal fungus (AMF) in the soil on the response of canavalia to the inoculation with an efficient strain of AMF, they were carried out several experiments with different conditions of initial content of spores and handling of mycorrhizical inoculant: (group 1) soils in those that never this biofertilizer type had been applied before and the initial number of spores of AMF was low; (group 2) soils with high initial number of spores and in the one that they have been carried out successive applications of biofertilizers with the specie of AMF Glomus cubense (strain INCAM-4) during several years and (group 3) soils where this biofertilizer had never been applied and in the one that was caused by means of a previous cultivation of plants (spontaneous vegetation and Brachiaria sp.), a high initial number of native spores of HMA. In the soils with smaller initial number of spores of HMA (group 1) the canavalia had a positive response to the inoculation, with differences in the evaluate variable among the treatments with inoculation and without this. However, in the soils with previous applications of micorrizical inoculant and high number of spores (group 2) was not observed response from canavalia to the inoculation, although it presented an effective fungus colonization. In the soil with a high content of native spores (group 3), the canavalia had response to the inoculation, what evidences the high competitiveness and efficiency of the strains Glomus cubense (INCAM-4). In all the cases effect of permanency of the inoculation of the canavalia was presented on the mycorrhizical colonization of the later cultivation, in this case maize. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the effect of inoculating the arbuscular mycorrhizal fungi (AMF) strain Glomus hoi-like on the response of Brachiaria hybridcv. Mulato II (CIAT 36087) to organic and nitrogen fertilization. The experiment was carried out in the Pastures and Forages Station of the Genetic Breeding Enterprise "Niña Bonita" ,located in Artemisa province, on a Lixiviated Red Ferraliticsoil. Rates of 15 and 30 t of cattle dung.ha-1, 30 t of cattle dung.ha-1 combined with 150 kg N.ha-1.year-1, 15 and 30 t ofcattle dung.ha-1 combined with 0, 75 and 100 kg N.ha-1.year-1plus the inoculation of AMF strain Glomus hoi-like, and the corresponding controls without cattle dung or N, to establisheleven treatments, were assessed. These were distributed in arandom block design with four replications. Cattle dung improved the soil chemical properties when increasing its pH,organic matter and available P and K contents, and its effects was observed during the first two years after its application; the highest effects were observed with the application of30 t.ha-1. The inoculation of G. hoi-like combined with the application of 75 or 100 kg N.ha-1.year-1 produced the highest mycorrhizal colonization percentages, visual density and spore density, so as dry matter (DM) nutrient contents and DM yieldssimilar to those obtained with 30 t of cattle dung.ha-1 plus150 kg N.ha-1.year-1 without inoculation. The effects of G. hoi-like inoculation on the mycorrhizal structures and on the reduction of both fertilizer dosages was observed during the first two years of the experiment. [ABSTRACT FROM AUTHOR]

In order to determine the behavior of longitudinal variability in the number of spores of arbuscular mycorrhizal fungi (AMF) Glomus hoi-like in beds, using Brachiaria decumbens as a trap plant, a study was performed. To comply with it, the crop was inoculated with Glomus hoi-like (INCAM-4), provided by the AMF strain collection of INCA, on a clay substrate. Samplings were conducted at 60, 90 and 120 days after seed germination in which the beds were subdivided into three equal parts and took a sample of five sub-samples in the depth of 0-20 cm, determined the number of spores. To determine the spatial variability in the number of spores in a sample beds composed of three sub-samples every 1.5 m along the plant, each sample was tested for the number of spores and the contents of some chemical indicators substrate. A correlation between the number of spores and chemical indicators of the substrate were mode. The number of spores in both periods was increasing with time and showed a high variability throughout the bed. The highest production of spores were found in the period from June to October. The correlation between the amount of spores and chemical indicators showed poor results with very low correlation coefficients, which showed that these indicators are not responsible for the variability the spore production. [ABSTRACT FROM AUTHOR]

The study was carried out at the National Institute of Agricultural Sciences (INCA) on a Lixiviated Red Ferralitic soil, with the objective of evaluating the effect of the combined inoculation of Bradyrhizobium elkanii and arbuscular mycorrhizal fungi, along with the application of a crop growth biostimulator, on soybean response of INCAsoy-24 cv. A randomized block design with four repetitions per treatment was employed, which consisted of inoculating these microorganisms, in their single and cocktail forms, by means of a seed recovery technology, as well as applying a crop growth biostimulator through different ways to the previous treatments. Results showed a positive effect of the combined inoculation of both biofertilizers on soybean cultivar growth and yield, with increments of 31,2 %, so confirming the synergical and beneficial effects of Bradyrhizobium elkanii-arbuscular micorrhiza fungal coinoculation in this crop. Increments were slightly higher when applying crop growth stimulator to this treatment, it showing no significant differences, either by seed recovery or leaf application, with values of about 37,6 and 34,4 % respectively. Treatments where the biostimulant was applied showed better yields than the controls; thus, production increments from 2,44 to 14,91 % were achieved, according to the treatment evaluated, it proving its effectiveness on crop growth stimulation. [ABSTRACT FROM AUTHOR]

Some green manure species can increase the potential content of soil mycorrhizal fungi, since they improve P absorption and the subsequent crop yields, compared to fallow systems. This experiment was conducted with this purpose in 5-kg-capacity pots containing Nitisol from September to November 2007 and 2008. A randomized complete experimental design was used with six replicates. Treatments consisted of sowing two seeds of Canavalia ensiformis per pot besides adding 10 g of certified inoculum (25 AMF spores.g-1 inoculum), selecting strains from Glomus mosseae, Glomus claroideum and Glomus hoi-like species out of INCA's strain bank. Non-inoculated plants and non-sterilized soil were used as check control. Dry weight, leaf analysis and AMF spore count were determined and the best results were obtained by Glomus hoi-like. Results showed a notable NPK absorption difference between strain-inoculated plants and the noninoculated control. A soil AMF spore multiplication effect was observed, after cutting strain-inoculated jackbean plants. The positive answer to AMF inoculation depends on two factors: the inoculated species and substrate nutrient richness [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) are symbionts associated to most terrestrial plants and have an important role in soil aggregation. However, there is a debate regarding how much soil aggregates depend primarily on particle grilled by fungal hyphae or organic substrate exudation such as glomalin. This review also considers whether glomalin really plays a key role on soil aggregation or if it is simply a fungal physiological function byproduct. [ABSTRACT FROM AUTHOR]

With the aim of evaluating green manures applied to mycorrhized coffee seedling production on Gleyic Cambisols, four species were grown and characterized: Sorghum vulgare, Crotalaria juncea, Canavalia ensiformis and Dolico lablab. They were later cut and added to the soil for obtaining different substrates at 70 days, in order to study coffee response to an efficient AMF strain inoculation, using a randomized complete design with (6x2) factorial arrangement, besides including single soil and soil/earthworm humus (3/1) treatments. The experiment was replicated for three years. The greatest dry weight production was achieved by sorghum, followed by crotalaria (20 %) and canavalia (50 %), whereas dolico showed a worse performance. The highest N content (near 200 kg.N.ha-1) was recorded in crotalaria, which was relatively similar to sorghum and canavalia (150 kg). The highest P and K contents were recorded in sorghum. Green manures increased native mycorrhizal propagules in the substrate and, thereby, native seedling mycorrhization; however, it was not so effective. Therefore, a significant coffee response to mycorrhizal inoculation by Glomus intraradices was observed with any green manure. The use of sorghum, crotalaria and canavalia assured nutrient requirements for an optimum mycorrhizal growth and functioning of inoculated seedlings, so that there is no need to apply other organic manures. [ABSTRACT FROM AUTHOR]

This research work was aimed at evaluating soybean (Glycine max) Verónica var. response to coinoculation with arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) by using Glomus hoi like and Bradyrhizobium japonicum respectively in Santa Cruz de la Sierra, Bolivia. The experiment was carried out in winter seeding, 2005. Seed-coinoculating treatment by AMF-PGPR was compared with two PGPR-inoculated controls and seeded directly on the farm, in plots which were harvested 150 days later. Coinoculated soybean achieved the best yield and cost-benefit ratio. [ABSTRACT FROM AUTHOR]

Anthurium is a much appreciated ornamenta plant for its elegant leaves and beautiful flowers. It is a slowly growing crop that completes its physiological cycle by going through three stages or phases: adaptation, acclimatization and nursery. Tissue culture is its most appropriate reproduction form and its development is based on available slightly acid -3 substrates with a bulk density of about 0.60 kg.cm-3 and an estimated organic matter content of 25 %. It also requires well aerated substrates. Besides, it is necessary to take into account other influential aspects to obtain a good seedling, such as mineral fertilization, use of growth promoters and, in the last decades, addition of soil microorganisms as biofertilizers. Ex perimental works were developed at the nursery stage in the National Institute of Agricultural Sciences (INCA), over the period of June/2004- January/2006, with the objectives of localizing and characterizing adequate carriers to satisfy plan needs; preparing, characterizing and defining the possible influence of different substrate formulas on plants within this stage; determining the influence of different substrate pH values as well as evaluating the effects of AMF biofertilization on seedling growth in tested substrates. Results showed Anthurium answer to different substrates used, standing out those mixing acid peat+filter cake+zeolite, so proving the significance of substratum pH on crop development and growth, 6,5 being the most appropriate one. In general, a positive effect was recorded after applying mycorrhiza biofertilizers to Anthurium growth, these treatments showing a higher growth than those without it. [ABSTRACT FROM AUTHOR]

The optimal crop development demands a higher application of mineral fertilizers and pesticides. The use of such chemicals involves not only high cost and energy requirements, but their indiscriminate contribution could cause salinity troubles and ground water pollution. Plant development can also be improved by using biological elements that co-ordinately act in the soil-root interface; among them and as an essential factor are arbuscular mycorrhizal fungi, which are capable of colonizing 95 % land plants. A recent study on the microbial community associated to arbuscular mycorrhizal fungi (AMF) has provided a fungal knowledge; bacteria, filamentous fungi and yeast associated to AMF structures have been observed. This paper is aimed to analyze the evident tripartite interaction between AMF, plants and other microorganisms, and to release the main scientific contributions associated to this phenomenon. [ABSTRACT FROM AUTHOR]

Indisputable ecological agriculture advances are closely linked to the proven risk, provoked to human health by foods containing toxic residuals derived from pesticides and mineral fertilizers, which has encouraged an international movement, intended to improve its biological quality by means of using available natural resources in agroecosystems. Cuba is not kept out of this situation and proposes some ecological alternatives to manage agricultural crops developed under a protected cultivation system, which are great chemical consumers. This work was carried out under protected cultivation housing conditions aimed at studying the effect of mycorrhizae and brassinosteroid analogues as ecological alternatives for tomato production under such productive system. There were seven completely randomized treatments referred to the single and combined application of bioproducts as well as its combination with mineral fertilization, so that they allowed reducing the mineral fertilization applied to crop under these conditions. According to results, when there are statistical differences compared to production control, ecological product combination stimulates plant growth and crop production. The combined application of mycorrhizaebrassinosteroid analogues (three times) + 50 % mineral fertilization enabled to obtain a larger amount of bunches (11.2) and fruits (21.0) per plant, with a fruiting percentage of 92.4 %, leading to an agricultural yield of 51.46 t.ha-1, the 50 % mineral fertilization reduction being significant to be applied under a protected cultivation system. [ABSTRACT FROM AUTHOR]

The technology used for potato (Solanum tuberosum) micropropagation still has some problems, so that it does not fully guarantee the conditions for the further development of derived plants under natural environments. Inoculation with arbuscular mycorrhizal fungi (AMF) at in vitro phase could be an alternative to eliminate some of these problems, by its positive influence on vitroplants obtained with a greater ability of survival and adaptation. This work was aimed at evaluating the behaviour of antioxidant enzymes -peroxidase, polyphenoloxidase and superoxide dismutase- and vitroplant growth mycorrhized in vitro with two AMF species: Glomus mosseae and Glomus hoi-like. Thus, potato vitroplants of Desirée cv. were cultivated in sterile containers with a mixture of vermiculite and twice the components of M (minimum) culture media. In this stage, disinfected spores of both AMF were inoculated, which together with the control without inoculation constituted the three treatments studied. Once mycorrhized, vitroplants were transferred to the acclimatization phase and transplanted to pots. Results indicate G. mosseae is the best species in both phases; since greater intraradical fungal growth as well as superior values of aerial fresh mass and leaf number were observed in plants inoculated with this species. Differences detected among treatments were biochemically corroborated with the changes found in enzymatic activities and mainly in isoenzymatic expression. This suggests the use of AMF for obtaining micropropagated potato plants mycorrhized at in vitro stage, which should have a greater ability for survival and adaptation. [ABSTRACT FROM AUTHOR]

The effect of different organic alternatives on Gerbera jamesonii seedling growth and development during nursery phase was studied in this paper. Plants were settled down in September 2002 and 2003 with three different nutritional alternatives: AMF-EcoMic 2 g.plant-1, organic fertilization 30 g.alveolus-1 and chemical fertilization-complete formulation 9-13-17. They were cultivated in expanded polyesthyrene and pyramidal trunk trays, protected by a tunnel of 10 m long and 7 m wide and recovered with an antiaphid mesh and a zaran with 30 % light. Regressions were used to seedling growth and development analysis; results demonstrated the feasibility of employing organic matter in gerbera nurseries, either to plant germination or seedling growth and development in general. Growth rate was established for leaf surface, total dry weight, aerial dry weight and root dry weight, fixing data to a second-degree poynomic exponential equation (y=e(b0+b1X+b2X2)) or a second-degree polynomial function (y=bo+b1X+b2X²). AGR and NAR were calculated from total dry weight equation using the functional method. Plants inoculated with micorriza showed that gerbera is a micotrophic plant. In general, the study allowed to conclude that when the substrate is organically well supplied, it is possible to diminish up to 50 days the nursery stay, which is an important aspect for producers. [ABSTRACT FROM AUTHOR]

An experiment was carried out under field conditions on a Lixiviated Red Ferralític soil, with the objective of evaluating the effect of three strains of arbuscular mycorrhizal fungi on the growth and development of guinea grass (Panicum maximum cv, Likoni). Four treatments were studied (control and the inoculation of AMF strains Glomus hoi-like, Glomus mosseae and Glomus intraradices) arranged in a Latin square design. The mycorrhizal formulation was applied at sowing by the seed recovering method with an equivalent dose to 10 % of its weight. The guinea grass was cut every each six and eight weeks in the rainy and dry seasons, respectively, evaluating in each cut the percentages of root colonization and visual density, as well as height, biomass nutrient contents and dry matter yield. With the inoculation of the strain Glomus hoi-like, the highest colonization and visual density levels and NPK contents were obtained in the air biomass. This strain also produced the biggest height and tiller diameter and dry matter yields of the guinea grass. Among the evaluated strains, Glomus hoi-like showed the highest indexes of efficiency and participation in grass nutrition. According to the exposed results, the strain Glomus hoi-like was effective to improve the nutritional status and dry matter yields of the guinea grass cultivated in this type of soil. [ABSTRACT FROM AUTHOR]

The physiological response of tomato crop (Lycopersicon esculentum) cv INCA 9 (1) was studied after applying two inoculant forms made up of Glomus sp1 (INCAM 4): one in a solid medium and the other in a liquid medium. The solid inoculant was directly put in the substrate of the pots at a single dose and time, whereas the liquid inoculant was sprayed by means of drop irrigation system at different doses and times. The experiment was carried out in a cooling-equipped polycarbonate greenhouse for temperature and relative humidity control. Results showed that the highest colonization and fungal occupation percentages were reached 40 days after seed germination in the liquid inoculant treatments. Soil moisture values were similar in all treatments, indicating that an adequate irrigation regime was supplied to plants, in order to guarantee the same water requirements during all the experimental period. In general, the values of water relations, gas exchange, dry biomass growth and morphological growth variables were higher when plants were treated with the liquid inoculant through irrigation, independently of the dose and time used. [ABSTRACT FROM AUTHOR]

This experiment was designed to define the mycorrhizal functioning of LicoMic®, a liquid biofertilizer with the arbuscular mycorrhizal fungus (AMF) Glomus sp1 (INCAM-4) under saline flooding soil conditions. A completely randomized design was done, where seed of rice (Oryza sativa) var J-104 was treated with a dose of 20 spores.seed-1 of liquid suspension of LicoMic® and a control treatment without it. Growth dynamics during 90 days and mycorrhizal functioning were determined as well as the calculation of external mycelium: arbuscular endophyte ratio (EM:AE), as an indicator of mycorrhizal behavior. Up to 18 days, the highest values of morphological measures were recorded in the control treatment; however, that situation changed, starting by the highest increments in the inoculated treatment. On the other hand, mycorrhizal variables had a typical microbial behavior. When analyzing visual density and arbuscular endophyte functioning, a very well latent phase was defined, where the fungus slowly colonized the inner root from 0 up to 20 days, starting an exponential growth up to 40 days; after this time, a stabilized phase to the final crop was observed. On the contrary to external mycelium, an initial concentration increase was also observed, following a stationary-diminishing phase to the final crop. According to EM:AE, two mycorrhizal association phases could be appreciated, an initial-transition up to 25 days and another one starting by this moment, both concurrent with plant growth dynamics. The highest yield increments were found in the mycorrhizal treatment, which demonstrates the good adaptability of this kind of mycorrhizal species to such salinity conditions. [ABSTRACT FROM AUTHOR]

The influence of three strains of arbuscular mycorrhizal fungi (Glomus claroideum, Glomus mosseae and Glomus sp) on potato vitroplant acclimatization, clon 6-457, was studied. The percentages of mycorrhizal colonization and fungal density, as well as the growth variables: plant height, leaf number, nodal cutting number, and plant survival, were determined. Besides, leaf peroxidase and polyphenoloxidase activities and their isoenzyme expression were analyzed. In general, a positive effect of Glomus sp and G. claroideum strains on potato vitroplants was observed, Glomus sp-inoculated treatment being remarkable for the superior values recorded in fungal and growth variables evaluated. Indeed, enzymatic activities were repressed by Glomus sp, suggesting a minor stress of potato plants inoculated with this strain, as well as a better acclimatization in this stage. Isoenzymatic patterns did not show mycorrhization effect, due to differences among treatments were not detected and a new symbiosis-specific isoform was not expressed either. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal colonization and nodulation in cowpea (Vigna unguiculata L. Walp) plants growing in soils under alley-cropping, low-input continuous cropping, secondary forest, and bare soil on a slope were evaluated at 5, 15, 30 and 45 days after seed germination (DASG) under greenhouse conditions. Mycorrhizal colonization and nodulation in cowpeas differed greatly at their early growth stages in spite that any of the systems studied received phosphorus fertilizers. At similar low levels of soil available phosphorus in different soils, high levels of mycorrhizal colonization (low-input continuous cropping system) may be advantageous for plant growth and nodulation. Nodulation was absent in cowpeas growing in the secondary forest soil probably due to repressing effects of high levels of nitrogen in soil or to the lack of rhizobia for cowpeas. In the bare soil plot, cowpeas had a very low level of mycorrhizal colonization. Nodule formation was essentially zero, probably as effects of soil loss due to rainfall. Results obtained suggest the need for re-introduction of soil microorganisms for revegetation and land reclamation programs in severely disturbed soils like road banks, gas and oil pipelines, mining exposed areas, and others. [ABSTRACT FROM AUTHOR]

, Los bosques secos tropicales (BST) se distribuyen en regiones con una fuerte estacionalidad de lluvias donde hay al menos 3 meses de sequía (menos de 100 mm) [1]. Los modelos climáticos predicen condiciones más calientes y más secas para finales del siglo XXI para grandes regiones del neotrópico [2], pero se sabe poco sobre cómo afectarán estas condiciones a las plantas de BST, sobretodo en estadios tempranos. En particular, es muy poco el conocimiento que se tiene sobre cómo puede afectar la sequía a las interacciones entre plantas y otros organismos como los mutualistas del suelo, y cómo los diferentes grupos funcionales de estos organismos (micorrizas arbusculares y bacterias fijadoras de nitrógeno) pueden ayudar a las plantas a enfrentar condiciones climáticas extremas [3]. Para este estudio se llevó a cabo un experimento con plántulas de 3 especies de leguminosas fijadoras de nitrógeno (Pseudosamanea guachapele, Samanea saman y Pithecellobium dulce), 2 especies de leguminosas no fijadoras de nitrógeno (Hymenea courbaril y Senna spectabilis) y 4 especies no leguminosas (Sapindus saponaria, Spondias mombin, Guazuma ulmifolia y Hura crepitans) de bosque seco, con y sin microorganismos de BST. Las plantas que crecieron con microorganismos del suelo fueron inoculadas con suelo y raíces frescas colectados en un bosque seco del Valle del Cauca, mientras que las que crecieron sin microorganismos del suelo crecieron en suelo esterilizado. Las plántulas crecieron bajo tres tratamientos adicionales de precipitación (riego): control (C), cantidad de precipitación reducida (P) y frecuencia de precipitación reducida (P). Se encontró que las leguminosas fijadoras de nitrógeno se asocian con bacterias fijadoras de nitrógeno y micorrizas arbusculares (MA), mientras que las leguminosas no fijadoras y las plantas no leguminosas se asocian únicamente con MA. Las plantas en el tratamiento de control recibieron la cantidad de agua correspondiente a lo que llueve en un bosque seco (160 ml por semana), mientras las plantas en el tratamiento P recibieron la mitad de esa precipitación (80 ml por semana), y las del tratamiento F recibieron la misma cantidad de agua que las del control, pero cada dos semanas (160 ml cada dos semanas). Las plantas asociadas con MA tuvieron una mayor mortalidad que aquellas que se asocian con MA y bacterias fijadoras de nitrógeno bajo los dos tratamientos de sequía. Adicionalmente, los costos y beneficios de las micorrizas y las bacterias fijadoras de nitrógeno variaron según la especie y el tratamiento de sequía. Estos resultados sugieren que los cambios que se predicen para el clima no solo pueden afectar a las plantas, sino también a sus simbiontes del suelo en formas que hasta ahora empezamos a entender. [ABSTRACT FROM AUTHOR]

Los bosques secos tropicales (BST) se distribuyen en regiones con una fuerte estacionalidad de lluvias donde hay al menos 3 meses de sequía (menos de 100 mm) [1]. Los modelos climáticos predicen condiciones más calientes y más secas para finales del siglo XXI para grandes regiones del neotrópico [2], pero se sabe poco sobre cómo afectarán estas condiciones a las plantas de BST, sobretodo en estadios tempranos. En particular, es muy poco el conocimiento que se tiene sobre cómo puede afectar la sequía a las interacciones entre plantas y otros organismos como los mutualistas del suelo, y cómo los diferentes grupos funcionales de estos organismos (micorrizas arbusculares y bacterias fijadoras de nitrógeno) pueden ayudar a las plantas a enfrentar condiciones climáticas extremas [3]. Para este estudio se llevó a cabo un experimento con plántulas de 3 especies de leguminosas fijadoras de nitrógeno (Pseudosamanea guachapele, Samanea saman y Pithecellobium dulce), 2 especies de leguminosas no fijadoras de nitrógeno (Hymenea courbaril y Senna spectabilis) y 4 especies no leguminosas (Sapindus saponaria, Spondias mombin, Guazuma ulmifolia y Hura crepitans) de bosque seco, con y sin microorganismos de BST. Las plantas que crecieron con microorganismos del suelo fueron inoculadas con suelo y raíces frescas colectados en un bosque seco del Valle del Cauca, mientras que las que crecieron sin microorganismos del suelo crecieron en suelo esterilizado. Las plántulas crecieron bajo tres tratamientos adicionales de precipitación (riego): control (C), cantidad de precipitación reducida (P) y frecuencia de precipitación reducida (P). Se encontró que las leguminosas fijadoras de nitrógeno se asocian con bacterias fijadoras de nitrógeno y micorrizas arbusculares (MA), mientras que las leguminosas no fijadoras y las plantas no leguminosas se asocian únicamente con MA. Las plantas en el tratamiento de control recibieron la cantidad de agua correspondiente a lo que llueve en un bosque seco (160 ml por semana), mientras las plantas en el tratamiento P recibieron la mitad de esa precipitación (80 ml por semana), y las del tratamiento F recibieron la misma cantidad de agua que las del control, pero cada dos semanas (160 ml cada dos semanas). Las plantas asociadas con MA tuvieron una mayor mortalidad que aquellas que se asocian con MA y bacterias fijadoras de nitrógeno bajo los dos tratamientos de sequía. Adicionalmente, los costos y beneficios de las micorrizas y las bacterias fijadoras de nitrógeno variaron según la especie y el tratamiento de sequía. Estos resultados sugieren que los cambios que se predicen para el clima no solo pueden afectar a las plantas, sino también a sus simbiontes del suelo en formas que hasta ahora empezamos a entender. [ABSTRACT FROM AUTHOR]

Las diferentes actividades desarrolladas por el hombre, el cambio climático y la distribución restringida de las especies ha aumentado la probabilidad de extinción de las mismas. Puya nítida es una especie de la familia bromeliaceae nativa y endémica de Colombia, distribuida en los páramos y subparamos, entre los 2700 a 3700 m.s.n.m. que se encuentra casi amenazada, a pesar de ello ha sido poco estudiada. Una de las estrategias de conservación es la reintroducción de especies, sin embargo para que esta sea efectiva se deben tener en cuenta una serie de características como la fertilidad del suelo y la microbiota asociada a la especie. Con el fin de contribuir al entendimiento de las interacciones microbiológicas de P. nitida, se buscó determinar si se presenta asociación simbiótica con Hongos Formadores de Micorrizas Arbusculares (HFMA). Para ello se realizó un muestreo de suelo y raíces a 10 cm de profundidad. La micorrización se evaluó mediante variables como porcentaje de colonización de raíces, número de esporas en 100g-1 de suelo seco y caracterización de esporas presentes. Se evidencio la presencia de las estructuras características del HFMA presentándose en todas las muestras de raíces un alto porcentaje de micelio intraradical (43-65%), presentando diferencias significativas (p<0,05) entre estructuras (vesículas, esporas y arbúsculos), el número de esporas encontrado en el suelo rizosférico de la especie estuvo en un rango de 128 a 351 esporas en 100g-1 de suelo seco y se observó la presencia de esporas asociadas al género Acaulospora y Glomus. A partir de los resultados se comprobó la simbiosis entre los HFMA y la especie P. nítida en la zona geográfica evaluada, lo cual es importante en programas de reintroducción de la especie por las ventajas que representa la simbiosis al mejorar la captación de nutrientes por parte de la planta, resistencia a estrés hídrico, agregación del suelo, producción y acumulación de sustancias de crecimiento. [ABSTRACT FROM AUTHOR]