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The abundance and diversity of indigenous Trichoderma fungi were tested for correlations with the natural colonization of symbiotic arbuscular mycorrhizal fungi (AMF) in Cd-, Zn- and Ni-polluted soils. Infection frequency (F%) and arbusculum richness (a%) of the mycorrhiza fungi were estimated on red clover grown in a pot experiment set up with calcareous loamy chernozem soil contaminated with Cd, Ni and Zn salts (in 0, 30, 90 and 270 mg kg -1 dry soil concentration) in the field, eight years prior to the pot experiment. Correlation analyses were used to assess the effect of different heavy metal loads on the interrelations of these two types of beneficial fungi. When the test was performed for single variables, significant correlations could be found with very close (r > 0.96 at p < 0.05) results. The rate and direction (positive or negative) of correlations, however, varied with the type of heavy metals. With the combinations of some Trichoderma and mycorrhiza parameters a significant model was obtained for the infection frequency (R² = 0.9405 at p = 0.0062) and for arbusculum richness (R² = 0.997 at p = 0.0007), which suggests a significant complex influence between the symbiotic (AMF) and the free-living ( Trichoderma ) beneficial fungi. This interaction was altered by heavy metals. In the Ni treatments, the correlation data were always negative between the two groups of beneficial fungi.  

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Dominant halophytes, such as Plantago maritima, Aster tripolium, Artemisia santonicum, Puccinellia limosa, Festuca pseudovina and Lepidium crassifolium were monitored for their colonization by arbuscular mycorrhizal fungi (AMF) for two vegetation periods, sampled by monthly frequency. Two saline sites (A: Apaj-puszta and Z: Zabszék) were selected for the survey due to their similar physical and chemical soil characteristics (including the salt level and salt specific anions) and the distinct site use (pasturing or not) or water regime (as drought or temporally flooded at the vicinity of the Zabszék lake).  Colonization of arbuscular mycorrhizal fungi greatly depended on the plant species and their physiological status, such as the mycotroph or non-mycotroph character. In this respect the highest mycorrhizal intensity (M%) and arbusculum richness (A%) was found on the Plantago maritima , while Puccinellia limosa was the less dependent species on mycorrhiza fungi.  A characteristic seasonal dynamism was found at both saline sites, for all sampled halophytes. A maximum mycorrhizal colonization was recorded in late spring and early summer, when there was an increased plant-physiological initiative for the helpful symbiosis (i.e. intensive vegetative and/or generative phases of the hosts).  The rate of fungal intensity in the root system (M%), and especially the arbusculum richness (A%) on the other hand was found to be dependent on the site use and the water fluctuation in the soils. A more versatile dynamism of the mycorrhizal colonization was found therefore at the vicinity of the Zabszek lake with the permanent water fluctuations. Under more drought stressed conditions an increased mycorrhizal colonization and functioning (arbusculum richness) was found, generally preceeding the high environmental stress, which was deleterious for both symbiont partners. Such mycorrhizal dynamism in the rhizosphere, however, seems to be a common strategy between the hosts and the microsymbionts in the “struggle for life” process in the Hungarian steppe.

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A pot experiment was designed to study the colonization of indigenous arbuscular mycorrhizal fungi (AMF) on barley ( Hordeum vulgare L.) host plant. Soils of the pots were collected from a long-term field microelement loading experiment on calcareous chernozem soil twelve years after 13 heavy metals (Al, As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sr and Zn) were applied once in four doses (0, 30, 90 and 270 mg element·kg -1 d.w.). The biomass production and element accumulation of the host plant, the various colonization values of the arbuscular mycorrhiza fungi (AMF) – such as colonization intensity (M %), arbusculum richness (A %) in the root system and the sporulation intensity (g -1 dry soil) in the rhizosphere – were measured. When considering the twelve-year adaptation process of the AM fungal populations at the various metal loads, a relatively balanced inside mycorrhiza colonization was found, suggesting the potentials for the selection of tolerant fungi in metal contaminated soils. The balanced infection intensity (M %) of the AM fungi and their common strategies with the host plant have resulted a nonsignificant shoot and root biomass production of barley in general. Mycorrhiza sporulation in the root system proved to be much variable and indicated the toxicity of metals and metal rates. Cd, Pb and Sr elements significantly reduced spore numbers, while a value of 34 spores·g -1 soil was counted in the case of Ni in comparison to the control’s 22 spores·g -1 soil value. Stress-defending strategies of the fungal–plant symbiosis, such as the increased arbusculum richness (A %) could be established for the Hg and Pb rates. In the case of Cd an increased root biomass production became a tool for stress alleviation and reduced the metal allocation towards the shoots. Mycorrhiza fungi are part of the common plant–microbe interactions and appropriate defending mechanisms in metal contaminated soils.

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The relationship between some soil physical-chemical characteristics, with more focus on the types of salt-specific anions and the colonisation parameters of the arbuscular mycorrhizal fungi (AMF) were examined on the most dominant halophytes, grown at four saline soils in Hungary. At site Z (Zám) mainly the chloride, at site Ny (Nyírõlapos) mainly the sulphate ions dominated in the soil samples, while at site A (Apajpuszta) and site Zsz (Zabszék) the carbonate anions were the most frequent. A large colonisation variability of the AM fungi were found in the four saline sites and the studied halophytes. Among the affecting soil-plant factors a strong host dependency was recorded with almost no mycorrhiza colonisation on Puccinellia limosa and the highest values at the Plantago maritima and Aster tripolium . As a function of the salt-levels a relative location of the halophytes could be found at each sites. The AMF colonisation intensity (M%) and functioning, measured as arbusculum richness (A%) was reduced with the overall increasing salinity, more particularly with the total cation-content of the soils. The deleterious effect of some other abiotic factors, i.e., the very poor or rich nutrient availability and the humus accumulation tended to be also negatively correlated by the mycorrhizal parameters.

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Üvegházi körülmények között savanyú barna erdotalajban nevelt fehér here (Trifolium repens L.) növények rizoszférájának sókezelés hatására bekövetkezo változását ellenoriztük. Megvizsgáltuk a különbözo sókoncentrációknak (0, 0,2, 0,4, 0,6 és 0,8 tömeg %) a baktériumnépesség összetételére és a különbözo talajenzimek aktivitására gyakorolt hatását.  Megállapítottuk, hogy a talaj sótartalma közvetlenül befolyásolta a rizoszférában található fluoreszkáló pszeudomonaszok csíraszámát. A legsurubb populáció a 0,2% NaCl-ot tartalmazó talajban volt mérheto, ahol a fluoreszkáló pszeudomonaszok között a Pseudomonas putida és a P. fluorescens fordultak elo a legnagyobb számban. A pszeudomonaszok ily módon jól tolerálják a talaj magas NaCl-tartalmát, és gyökérkolonizáló tevékenységet képesek kifejteni a magas NaCl-tartalmú talajban is. A sókoncentráció növelésével kezdetben (a 0,2-0,4%-os tartományban) jelentosen növekedett a dehidrogenáz, kataláz, és ureáz enzimek aktivitása. A proteáz enzimek aktivitásmaximuma a 0,1-0,2% NaCl-koncentráció tartományba esett. A 0,4%-nál magasabb koncentrációkban a kontrollhoz hasonló mértékure csökkent mind a négy enzim aktivitása, és a baktériumok száma is. A foszfatáz- és a b-glükozidáz-tevékenység viszont a NaCl-dózis növelése következtében a koncentrációval arányosan, jelentosen csökkent a kontrollhoz viszonyítva.  Feltételezésünk szerint az enzimaktivitások változását is a sókezelés hatására bekövetkezo mikrobióta összetételének megváltozása okozta.

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