Diversity of ectomycorrhizal fungus assemblages on nursery grown European beech seedlings

? Context

An important feature of forest nursery management is the production of first-rate planting stock, which is closely connected with an adequate development of ectomycorrhizas on seedling roots.

? Aims

The aim of this study was to provide a detailed assessment of the ectomycorrhizal (ECM) fungal diversity of European beech grown in bare-root forest nursery conditions.

? Methods

Morphological and molecular analyzes were used to identify ECM fungi, quantify fungal richness, and record differences in the relative abundance of individual taxa.

? Results

Twenty-seven different mycorrhizal fungal taxa were found in four tested nurseries. Of these 27, only 6 were present in more than one nursery. Taxa richness in individual nurseries ranged from 6 to 13, indicating that ECM colonization potential is nursery-dependent. The most frequent taxa were: Tuber sp. 1, Cadophora sp., Cenococcum geophilum agg., Hebeloma sacchariolens, and Laccaria tortilis. According to the analysis of similarity, ECM fungal communities were significantly different between nurseries (R?=?0.7741; p?<?0.0001).

? Conclusion

Beech seedlings grown in bare-root nurseries are colonized by a highly diverse suite of ECM fungi; thus, artificial inoculation of seedlings is generally not necessary in nursery practice.     

Ectomycorrhizal inoculation with Pisolithus tinctorius increases the performance of Quercus suber L. (cork oak) nursery and field seedlings

Mediterranean ecosystems are characterized by large arid areas where the patchy distribution of trees offers little protection against harsh climate conditions for seedling establishment. Climate change is predicted to result in an increase in these arid regions, with pronounced effects on vegetation. Production of seedlings with developed ectomycorrhizas is a promising strategy for minimizing the initial transplant shock, thereby increasing plant survival and growth during the first, most critical years of a plantation. One important species in the Mediterranean basin is Quercus suber (cork oak), which occurs, together with other evergreen oak species, in an agro-silvo-pastoral system that represents an example of sustainable land use in Europe. In this study, a Pisolithus tinctorius isolate was used for ectomycorrhizal colonization of cork oak nursery seedlings, and the effects on aboveground plant growth and leaf structural and physiological parameters were investigated. Ectomycorrhizal development resulted in a significant increase in leaf area, dry weight, nitrogen content, and photosynthetic pigments, and mycorrhizal plants showed a higher photosynthetic capacity and water use efficiency. Nursery-inoculated plants established in the field showed increased survival and growth during the first year after transplant. These results indicate a potential for further enhancing the use of mycorrhizal inoculation as a cultivation practice in forest nurseries. Considering the difficulty of soil restoration under limiting environmental conditions, nursery inoculation with ectomycorrhizal fungi can be an important advantage for improving the quality of seedling stock and its performance after out-planting in the field, benefiting the regeneration of arid regions and the reintroduction of inocula of ectomycorrhizal fungi into these areas.     

Assessing foraging strategies of herbivores in Mediterranean oak woodlands: a review of key issues and selected methodologies

Montados are agro-silvo-pastoral ecosystems, typical of the Southwest Iberian Peninsula, of high socio-economic and conservation importance, where grazing is a dominant activity. Montados are characterized by an open tree canopy of Quercus sp. and a diverse undercover of shrubs and grasslands that constitute the plant food resources for grazing animals. Plant food resources of Montados are highly variable, both spatially and seasonally, in quantity and quality. Reliable and easy to use methods to monitor grazing are necessary to allow proper understanding of foraging strategies of grazing animals and to set sustainable grazing management. We describe the main characteristics of the plant food resources available for grazing animals, striking its variability, and revise the potential of using N-alkanes and saliva proteome methods to assess foraging strategies in Montados. In a scenario of dynamic multiple choices, we discuss the use of n-alkane methodology for the simultaneous estimation of diet composition and voluntary intake and saliva proteome as a mean of increasing the knowledge on diet adjustments.     

Stickstoffdüngungsversuche in einer Fichtenwuchsstockung (Picea abies Karst.) auf devastierter Kalkmergel-Rendzina: III. Einflüsse von Ern?hrungszustand und Inokulation auf die Inhaltsstoffe von Bast und Holz

In einem kombinierten Düngungs- und Infektionsversuch wurden die Beziehungen zwischen dem Ern?hrungszustand, dem Wachstum und der Rotf?uledisposition von N-Mangel-Fichten auf Kalkmergel-Rendzina geprüft. Die vorliegende Arbeit berichtet über die Wirkung der N-Düngung und künstlicher Infektionen mit Heterobasidion-Mycel auf den Gehalt an Extraktstoffen im Bast und Holz. Wurzelbast vom August (nicht aber vom April) von mehrmals gedüngten Fichten enthielt mehr Chloroform-und Ethanol/Wasser-Extrakt sowie Zucker- und Phenolkomponenten als die ungedüngten Varianten. Auch das Wurzelholz gedüngter Fichten war im August reicher an Extraktstoffen. Die N-Gaben steigerten au?erdem in beiden Geweben den Gehalt an l?slichen N-Verbindungen. Im Stamm erh?hte die Düngung die Gehalte an. Methanol-Extrakt sowie an einigen N-haltigen und phenolischen Verbindungen nur im ?u?eren Splint.     

Infektionsversuche mit Rhizosphaera kalkhoffii und Lophodermium piceae an unterschiedlich gestreßten Jungfichten (Picea abies [L.] Karst.)

Young spruce trees [Picea abies (L.) Karst.] artificially inoculated with Rhizosphaera kalkhoffii B. and Lophodermium piceae (F.) v. H. were exposed to fumigations with O₃ and SO₂ and drought. These treatments showed no influence on the infection-rates of the fungi. R. kalkhoffii proved to be a saprophyte living for a long period as an epiphyte on the needle surfaces.     

The essential oil of Eucalyptus tereticornis, and its constituents α- and β-pinene,potentiate acetylcholine-induced contractions in isolated rat trachea

The effects of the essential oil of Eucalyptus tereticornis (EOET), especially the effects of its constituents α- and β-pinene, were studied on rat trachea in vitro. In tracheal rings, EOET, α- or β-pinene potentiated the contractions induced by acetylcholine (ACh). Contractions induced by K⁺ (60 mM) were also potentiated by α- and β-pinene, but were reduced by EOET. Our findings show that EOET has myorelaxant effects on rat airways, but potentiates ACh-induced contractions. Monoterpenes α- and β-pinene are involved in its potentiating actions, but are not responsible for its myorelaxant effects. A putative inhibition of the acetylcholinesterase enzyme is involved.     

A new dihydroxysterol from the marine phytoplankton Diacronema sp

Diacronema sp. was cultured and its sterols were separated by column chromatography on silica gel. The new sterol 24-ethyl-4alpha-methyl-cholestane-3,20-diol (1) was characterised by NMR and MS spectrometry, as well as (22E)-24-ethyl-4alpha-methyl-5alpha-cholest-22-en-3beta-ol (2) and beta-sitosterol, the major components of the sterol fractions. Neither the biosynthetic origin of the new dihydroxysterol nor its role in the biochemistry of Diacronema is known.     

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

Changes in soil chemical and microbiological parameters in small (185 m²) and medium (410 m²) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.     

Molluscicidal activity of Solanum species of the Northeast of Brazil on Biomphalaria glabrata

Seven species of Solanum were screened for their molluscicidal properties against Biomphalaria glabrata, the intermediated host of Schistosoma mansoni, Solanum agrarium, S. jabrense, S. melissarum, S. megalonyx, S. paludosum, S. paraibanum and S. stipulaceum. Four extracts showed molluscicidal activity with LC(50) from 22 to 56 microg/ml.     

Greenhouse biofumigation with <Emphasis Type="Italic">Melia azedarach</Emphasis> controls <Emphasis Type="Italic">Meloidogyne</Emphasis> spp. and enhances soil biological activity

The need for environmentally friendly agricultural practices has led to the development of plant-based nematicides for root-knot nematode control. The efficacy of these botanicals has been tested primarily under laboratory and rarely under actual field conditions. Moreover, any side effects on non-target soil organisms that support soil biological activity are usually ignored. Herein, we evaluate the efficacy of Melia azedarach preparations against Meloidogyne spp. in a tomato greenhouse, by root gall examination and soil J2 enumeration. We also assessed side effects on soil microbes through PLFA analysis and microbivorous nematodes, and we quantified several plant growth parameters (e.g., fruit number and weight, root weight). Different treatments within the greenhouse included M. azedarach ripe fruit powder (MFP), ripe fruit water extract (MWE) and furfural, one of the principal active ingredients of M. azedarach and previously known to exhibit fumigant nematicidal activity. Results were compared to those obtained with the commercial nematicide oxamyl (Vydate^® 10 SL) and an untreated control. All treatments were repeated every 20 days throughout the cultivation period. MFP and MWE suppressed Meloidogyne spp. often at the same levels obtained by furfural and oxamyl treatments and enhanced soil biological activity, as indicated by the proliferation of soil microbes and microbial feeding nematodes. Furfural and oxamyl adversely affected the soil community, especially the free-living nematodes. Moreover, furfural was phytotoxic to tomato plants in spite of its natural origin.