Molecular diversity of arbuscular mycorrhizal fungi in onion roots from organic and conventional farming systems in the Netherlands

Diversity and colonization levels of naturally occurring arbuscular mycorrhizal fungi (AMF) in onion roots were studied to compare organic and conventional farming systems in the Netherlands. In 2004, 20 onion fields were sampled in a balanced survey between farming systems and between two regions, namely, Zeeland and Flevoland. In 2005, nine conventional and ten organic fields were additionally surveyed in Flevoland. AMF phylotypes were identified by rDNA sequencing. All plants were colonized, with 60% for arbuscular colonization and 84% for hyphal colonization as grand means. In Zeeland, onion roots from organic fields had higher fractional colonization levels than those from conventional fields. Onion yields in conventional farming were positively correlated with colonization level. Overall, 14 AMF phylotypes were identified. The number of phylotypes per field ranged from one to six. Two phylotypes associated with the Glomus mosseae-coronatum and the G. caledonium-geosporum species complexes were the most abundant, whereas other phylotypes were infrequently found. Organic and conventional farming systems had similar number of phylotypes per field and Shannon diversity indices. A few organic and conventional fields had larger number of phylotypes, including phylotypes associated with the genera Glomus-B, Archaeospora, and Paraglomus. This suggests that farming systems as such did not influence AMF diversity, but rather specific environmental conditions or agricultural practice

Minerale voeding van de champignon

Slechte of matige groei, kwaliteit en opbrengst van champignons kunnen veroorzaakt worden door een tekort aan één of meerdere essentiële voedingsstoffen. De vraag is in hoeverre de voorziening met voedingsstoffen voldoende is om de behoefte van de champignon te dekken. Aanwijzingen voor eventuele tekorten zijn op verschillende manieren af te leiden uit een inventariserend onderzoek. Aan de samenstelling van champignons: - als het gehalte van een mineraal tijdens de ontwikkeling van de eerste vlucht afneemt, - als het gehalte van een mineraal tijdens de ontwikkeling sneller achteruitgaat dan van een ander mineraal,- als het gehalte van een mineraal in champignons van de tweede vlucht lager is dan die van champignons van de eerste vlucht. Mogelijke tekorten kunnen ook blijken uit de samenstelling van compost en dekaarde: - bijvoorbeeld als het totaal of het beschikbaarheidsgehalte van een mineraal aan het einde van de teelt lager is dan aan het begin. Ook uit de champignonopbrengst zijn mogelijke tekorten af te leiden: - als er een correlatie gevonden wordt tussen de opbrengst en het gehalte van een mineraal in compost of dekaarde. Het uitgevoerde onderzoek richtte zich op de macronutriënten stikstof, fosfor, kalium, zwavel, magnesium, calcium, en natrium en op de micronutriënten zink, ijzer, koper, en mangaan

Diversity of symbiotic root endophytes of the Helotiales in ericaceous plants and the grass, Deschampsia flexuosa

In a study of fungi growing in various root-associated habitats in and around Picea mariana, black spruce, in northern Ontario, Canada, an examination was made of the degree to which differences in growth sites within an area of a few square kilometers might influence the structure of root-associated filamentous microfungal populations. Picea mariana roots were collected at four strongly differing boreal forest sites: an undisturbed forest site with deep litter and humus layers; a recently regenerated forest; a clearcut, former portable sawmill site with a few small, naturally regenerated trees; and an open peat bog penetrated by roots from trees growing along the margin. Comparisons were done on isolate assemblages primarily from serially washed mycorrhizae, supplemented with comparison samples from washed root bark and adherent rhizosphere soil. The Bray & Curtis similarity index and nodal components analysis were utilised to identify trends within the data. Root endophyte fungi, mainly Phialocephala fortinii and Meliniomyces variabilis, were among the most common isolates from serially washed mycorrhizae and showed strong trends among the site types, with the former most common from sites low in humus and also low in known humus-associated microfungi, and the latter most common from the peat bog site. The overall composition of the isolate assemblages from washed mycorrhizae mainly reflected site factors, with assemblages from the undisturbed and regenerated forest sites similar to one another and those from the clearcut and peat bog sites strongly distinct. A major difference was also seen between two seasonal samples at the exposed clearcut site, but few seasonal differences were seen at the other sites. The regenerated and undisturbed forest sites were high in Umbelopsis isabellina, Mortierella verticillata and Penicillium spinulosum, fungi typical of humic horizons in boreal podzols; the clearcut yielded the greatest numbers of Fusarium proliferatum, Umbelopsis nana and Penicillium montanense isolates, an assemblage tending to indicate exposed mineral soil; while the peat bog was typified by the presence of characteristic northern peat inhabitants Mortierella pulchella and P. spinulosum, as well as temperate peat inhabitant Penicillium lividum. A synthesis of these results with other data suggests that as a microhabitat, the mycorrhizosphere, as originally defined by Foster & Marks, is of little significance in determining the structure of filamentous fungal populations in soil influenced by the presence of ectomycorrhizal forest tree roots. Edaphic and overall microbial community conditions are much more significant, but the influence of a ¿symbiorhizosphere effect¿ exerted by certain ectomycorrhizal symbionts within the whole soil volume they occupy is also known in some cases and worthy of further investigation

Service Interaction Flow Analysis Technique for Service Personalization

Abstract Service interaction flows are difficult to capture, analyze, outline, and represent for research and design purposes. We examine how variation of personalized service flows in technology-mediated service interaction can be modeled and analyzed to provide information on how service personalization could support interaction. We have analyzed service interaction cases in a context of technology-mediated car rental service. With the analysis technique we propose, inspired by Interaction Analysis method, we were able to capture and model the situational service interaction. Our contribution regarding technology-mediated service interaction design is twofold: First, with the increased understanding on the role of personalization in managing variation in technology-mediated service interaction, our study contributes to designing service management information systems and human-computer interfaces that support personalized service interaction flows. Second, we provide a new analysis technique for situated interaction analysis, particularly when the aim is to understand personalization in service interaction flows

Mycorrhizal fungal diversity in willow forests of different age along the river Waal, The Netherlands

In The Netherlands, riparian edge forests are often dominated by Salix species because they are well adapted to anaerobic soil conditions. Willows play therefore an important role in rehabilitation of natural riparian edge forests. They associate with both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi which are essential for successful restoration of natural ecosystems, but it is still unknown what communities of mycorrhizal fungi develop on Salix species in this environment. Salix alba L. (white willow) forests of three different ages (10, 20 and 60 years old) under restoration management along the river Waal were studied by molecular techniques to describe species composition of mycorrhizal fungi in roots and soil surrounding the trees. Presence of AM colonization was not determined in the roots of S. alba and only EM fungi were observed. Frequencies of EM root tips were below 9% at all sites. Twelve types of mycorrhizat fungi were distinguished in the roots. The mycorrhizal below-ground communities were dominated by Tuber species and to our best knowledge, this is the first molecular indication that Tuber spp. are associated with roots of Salix species. The basidiomycetous fungi including Hebeloma and thelephoroid spp. were found mainly in the 20-year-old forest with the lowest soil nutrient concentrations and were apparently able to withstand flooding. A tendency was observed for higher frequencies of mycorrhizal roots with lower nutrient concentrations and higher soil pH among the sites of different age. The results demonstrate that only a limited number of mycorrhizal fungi can resist the harsh conditions caused by flooding and drought

Prediction of wheat grain yield by measuring root electrical capacitance at anthesis

This methodological study evaluated the efficiency of predicting aboveground biomass and grain yield in fieldgrown winter wheat by measuring the saturation root electrical capacitance at anthesis. Three cultivars were grown over a threeyear period as sole crops and intercropped with winter pea at halved wheat density. The root capacitance readings were converted into saturation root electrical capacitance using the relevant soil water content, according to an empirical function. At plant scale, saturation root electrical capacitance at anthesis showed a significant (p < 0.001) linear regression with the total aboveground biomass (R2: 0.653-0.765) and grain yield (R2: 0.585-0.686) at maturity for each cultivar. At stand scale, both the mean saturation root electrical capacitance and shoot dry mass at anthesis and grain yield varied over the years, and were consistently higher for the intercrops compared to the sole crops. The relative increase in saturation root electrical capacitance due to intercropping corresponded with the changes in shoot dry mass and grain yield, especially in dry years. Saturation root electrical capacitance was significantly correlated with shoot dry mass (R2: 0.714-0.899) and grain yield (R2: 0.742-0.877) for each cultivar across all cropping systems and years. In conclusion, by mitigating the soil water content effect, the measurement of saturation root electrical capacitance at anthesis is adequate to forecast grain yield and cultivar response to a changing environment

Molecular analysis of amf diversity in aquatic macrophytes: A comparison of oligotrophic and utra-oligotrophic lakes

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