Solubilization of iron and calcium phosphates by soil fungi isolated from coffee plantations

Almost 900 fungal isolates were obtained from eight coffee plantations in Colombia and Mexico. Of these, 76 isolates showed activity to solubilize Ca₃(PO₄)₂ (PCa) and FePO₄·H₂O (PFe), which had been added to agar in a plate test. Generally, PCa was better solubilized than PFe. Colombian isolates were generally somewhat less effective than Mexican isolates. The two most effective isolates from each country with apparent highest PFe, solubilization potential were selected and cultivated in liquid medium containing PFe, which is more prevalent in tropical soils. The pH value, solubilized P in the medium and P uptake in fungal biomass were determined. After 24 days, Cylindrocarpon didymum and C. obtusisporum (both from Colombia) had solubilized 9.9 and 6.4 mg PO₄ ^3--P L^?1 and took up 8.6 and 11.6 mg P in biomass. Penicillium janthinellum and Paecilomyces marquandii (both from Mexico) solubilized 7.0 and 1.9 mg PO₄ ^3--P L^?1 and took up 11.3 and 17.3 mg P in biomass. The potential practical use of the four fungal isolates for different strategies in making more P available for coffee growth is discussed.     

Land use effects on carbon quality and soil biological properties in Eutric Cambisol

Abstract

The choice of prospective type of farming requires knowledge about the specific relationships that exist between farm management practices and base environmental conditions. Nowadays the protection of soil organic carbon is one of the main tasks, because organic carbon in addition to soil fertility can act in elimination of soil contamination and carbon sequestration. Field experiments were focused on the effect of intensive farming without organic inputs versus grassland on organic carbon content. Organic carbon content (C_ox) and humic substance fractions (C-humic acids and fulvic acid fractions), hot water extractable carbon and selected microbial characteristics in Eutric Cambisol were monitored during the period 1999–2010. A priming effect of soil cultivation was detected immediately after tillage. Arable soil with ‘intensive’ crop sequences (exclusively cash crops, cereals, oil plants) and with an optimal level of chemical inputs (mineral fertilizers, pesticides), but without organic farmyard manure had lower content of all carbon forms compared with grassland. ¹³C NMR spectroscopy and thermal analysis (TGA) were applied to characterize humic acid (HA) structure and stability. More carbon, less oxygen and more aromatic compounds were detected in grassland HA. Slight differences were found in HA thermo-oxidative stability and degradability, which was probably caused by changes in elemental composition and structure. Even the land use had no significant effect on basic microbiological characteristics (basal respiration, microbial biomass and qCO₂); the physiology of the microbial community of grassland was altered by a higher ability to utilize L- and D-glutamic acid. The L/D ratio of glutamic acid mineralization indicated no occurrence of stress in soil for both types of farming. It has been demonstrated that although losses of carbon as a result of land-use conversions are generally more rapid, gains of carbon in grassland followed by changes in management practices can also occur.     

First record of Chilodonella hexasticha (Ciliophora: Chilodonellidae) in Brazilian cultured fish: A morphological and pathological assessment

Chilodonelids are small ciliated protozoans found worldwide and can be dangerous in culture conditions. This study presents morphometric data on the ciliate Chilodonella that is found in cultured Nile tilapia (Oreochromis niloticus), native bait fish tuvira (Gymnotus aff. inaequilabiatus) and native pacu (Piaractus mesopotamicus) and includes a histopathological assessment of the changes that occur in the pacu. For parasitic diagnosis, skin and gill samples were scraped onto slides, dried at room temperature, stained with Giemsa or impregnated with silver nitrate, and the measurements were obtained from photomicrographs. In the diseased pacu, the first gill arch was collected and fixed in a 10% buffered formalin solution for histopathological analysis. Parasite specimens from the different collection sites were identified morphologically as C. hexasticha Kiernik (1909). Diseased fish exhibited depigmentation, skin ulceration, scale loss, excessive mucus production and gill lesions. Histopathological analysis of pacu gills displayed epithelial proliferation with mononuclear inflammatory infiltrate, hemorrhages, and scattering necrosis. In Brazilian-farmed fish this is the first record of C. hexasticha, which has great pathogenic potential in cultured freshwater species. In addition, two new hosts are presented.     

An evaluation of the ability of Dichelobacter nodosus to survive in soil

Background

Dichelobacter nodosus is the causative agent of footrot in sheep. The survival of the bacterium in soil is of importance for the epidemiology of the disease. The investigation evaluates the survival of D. nodosus in soil with and without added hoof powder stored under different temperatures.

Results

An experimental setup was used with bacteriological culture and real-time polymerase chain reaction (PCR), and the results indicate that the bacteria can survive in soil for longer time than previously expected. The survival time was found to be dependent on temperature and the addition of hoof powder to the soil, with the longest survival time estimated to be 24 days in soil samples with hoof powder stored at 5°C.

Conclusion

Our findings indicate that the survival time of D. nodosus and its ability to infect susceptible sheep on pasture under different climatic conditions should be studied further.     

Study of the transverse liquid flow paths in pine and spruce using scanning electron microscopy

Samples of pine (Pinus sylvestris) and spruce (Picea abies) were impregnated with a low-viscous epoxy resin using a vacuum process. The epoxy was cured in situ and the specimens sectioned. Deposits of the cured epoxy was then observed in the wood cavities using a scanning electron microscope. The investigation concentrated on tracing the transverse movements of a viscous liquid in the wood, and special attention was therefore given to the cross-field area between ray cells and longitudinal tracheids. A damage hypothesis is proposed based on the results obtained in the present investigation in combination with those from earlier studies on linseed oil-impregnated pine: In addition to the morphology of the bordered pits, viscous liquid flow in wood is dependent on damage that occurs during the impregnation procedure. For pine sapwood, liquid flow is enabled through disrupted window pit membranes, which divide the longitudinal tracheids and the ray parenchyma cells. A mechanism accounting for the reduced permeability of pine heartwood is believed to be deposits of higher-molecular-weight substances (extractives) in the ray parenchyma cells and on the cell walls. In spruce the thicker ray cells in combination with the smaller pits, which are connected to the longitudinal tracheids, reduce permeability considerably.     

Variations in sex ratio during an outbreak ofIps typographus (Col., Scolytidae) in Southern Bavaria

Extensive areas of spruce forest were affected by an outbreak of the Scolytid beetleIps typographus all over Southern Bavaria between 1990 and '95. During this gradation young beetles were collected from bark samples and examined with regard to the male to female sex ratio. It turned out that there is a significant interaction between gradation phase and sex ratio. An increase of population density was accompanied by an increasing portion of female beetles, up to 72%. A decrease of the females to an equal index of 5050 indicated the breakdown of mass propagation. This experiences could be used as an indicator of gradation phase and thus to create a new method of monitoring gradations of spruce bark beetle. The regulation mechanisms responsible for this deviation from a genetically plausible index of 11 can take influence as at the time of fertilisation as at embryonal or postembryonal development of the beetles. Parthenogenetic reproduction was not found inI. typographus.

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Veränderungen des Geschlechterverhältnisses beiIps typographus während einer Massenvermehrung in Südbayern

Zusammenfassung Im Rahmen einer Massenvermehrung des Buchdruckers in Südbayern (Raum München) zwischen 1990 und '95 wurden Jungkäfer aus Rindenproben im Hinblick auf die Geschlechterverteilung untersucht. Es zeigte sich eine Korrelation zwischen Gradationsphase und Sexualindex. Der Anstieg der Populationsdichte äußerte sich in einem erhöhten Weibchenanteil von bis zu 72%. Ein Rückgang des Weibchenüberhanges bis zum ausgeglichenen Geschlechterverhältnis von 5050 kennzeichnete den Zusammenbruch der Massenvermehrung. Es läßt sich also aus dem Sexualindex eine Prognose über die Dichteentwicklung einer Buchdruckerpopulation ableiten.Die Steuermechanismen, die für die Abweichung vom genetisch plausiblen Index 11 verantwortlich sind, können am Befruchtungsvorgang sowie an der embryonalen oder postembryonalen Entwicklung der Käfer ansetzen. Es konnten keine Hinweise auf eine parthenogenetische Vermehrung vonI. typographus gefunden werden.

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With one figure and one table

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These examinations were financially supported by the Bavarian Ministry of Food, Agriculture and Forestry.

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Dedicated to Prof. Dr.W. Schwenke for 75th birthday 22. 3. 1996.     

Swedish non-industrial private forest owners: a survey of self-employment and equipment investments

It has been estimated that Sweden’s non-industrial private forest (NIPF) owners undertake a total of 12 M hours of self-employed forest work per year. This paper reports an evaluation of self-employment in Swedish NIPF’s in terms of the people and equipment involved. NIPF owners’ self-employment was determined by a nationwide survey. Complete equipment sales statistics were compiled from interviews with manufacturers and importers. About 66% of NIPF owners are undertaking self-employed forestry work. Pre-commercial thinning was the activity undertaken most frequently by them, followed by planting, cutting and extraction. In comparison to other NIPF owners, self-employed NIPF owners tend to be younger, and are more likely to be male, single owners, resident on holdings, farmers and members of forest owner associations. Sales of new equipment suitable for self-employed individuals amounted to €67 M, or 83,000 items. Based on sales numbers and the profile of self-employed NIPF owners, no major changes in the amount and nature of self-employment are expected in the near future.     

Suspected natural lysosomal storage disease from ingestion of pink morning glory (Ipomoea carnea) in goats in northern Argentina

This study describes an occurrence of pink morning glory (Ipomoea carnea) intoxication in goats in northern Argentina. The clinical signs displayed by the affected animals were ataxia, lethargy, emaciation, hypertonia of the neck muscles, spastic paresis in the hind legs, abnormal postural reactions and death. The clinico-pathologic examination revealed that the affected animals were anemic and their serum level of aspartate aminotransferase was significantly increased. Cytoplasmic vacuolation in the Purkinje cells and pancreatic acinar cells was observed by histological examination. The neuronal lectin binding pattern showed a strong positive reaction to WGA (Triticum vulgaris), sWGA (succinylated T. vulgaris) and LCA (Lens culinaris). Although I. carnea is common in tropical regions, this is the first report of spontaneous poisoning in goats in Argentina.