Temporal variability of selected soil microbiological and biochemical indicators under different soil quality conditions in south-western Nigeria   总被引：1，自引：0，他引：1  

Barbara Wick  Ronald F. Kühne  Konrad Vielhauer  Paul L. Vlek 《Biology and Fertility of Soils》2002,35(3):155-167

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Effects of soil properties and land management on the structure of grassland snail assemblages in SW Germany     

Konrad Martin  Michael Sommer 《Pedobiologia》2004,48(3):193-203

Quantitative analyses of the snail assemblages of four a priori defined categories of grassland sites, characterized by soil moisture, land use and management, were conducted in SW Germany. Topsoil pH and calcium content were determined for each of 39 sites. The objectives were to study the effects of these habitat characteristics on snail density, species richness and quantitative structure of the land snail assemblages. With one exception, no significant relationships between soil pH (as a proxy for Ca supply) and the total numbers of individuals and species at the four site categories were observed. Snail density and species richness on groundwater soils, represented by rarely mown sedge stands and regularly mown meadows, were clearly higher than on intermediate moisture soils (as defined by the climatic water balance) of regularly mown meadows, indicating that soil moisture was the most important factor accounting for these differences. Furthermore, we observed specific conditions associated with the presence of trees in the category of meadow orchards on intermediate moisture soils. There, numbers of individuals and species were significantly higher than in the meadows on intermediate moisture soils. A posteriori cluster analysis of quantitative similarity of all snail assemblages showed that soil moisture accounts for the major differences between the site categories with respect to snail density, species richness and quantitative composition of the grassland snail assemblages. As these results are in contrast to the findings of many woodland studies, we suggest that the occurrence or abundance of certain species in the site categories are explained by land management, especially by frequent disturbances at the soil surface caused by mowing.  相似文献   

Gossypol and gossypolone enantiomers in tissues of rainbow trout fed low and high levels of dietary cottonseed meal     

Lee KJ  Dabrowski K 《Journal of agricultural and food chemistry》2002,50(10):3056-3061

Gossypol is an antifertilizing agent in males and females. However, gossypol and its metabolite, gossypolone, have also gained interest because of their anticarcinogenic activities. This paper examines for the first time both enantiomers of tissue gossypol and gossypolone in mature rainbow trout fed two diets containing low (15%) and high (60%) levels of cottonseed meal (CM) for 9 months. The gossypol concentration was highest in liver followed by kidney, intestine, testis, blood plasma, stomach, and muscle. Gossypol was detected in muscles of fish fed low- and high-CM diets (0.31 +/- 0.03 and 1.95 +/- 0.59 microg of total gossypol/g, wet basis, respectively). The (+)-gossypol enantiomer was predominantly retained in all tissues. The ratio of (-)- to total gossypol ranged from 30 to 44% in fish fed the high-CM diet and from 23 to 30% in fish fed the low-CM diet except for muscle tissue (44%). Higher gossypolone concentrations were found in intestine than in liver. Gossypolone, however, was not detected in blood plasma, muscle, and testis of fish fed the low-CM diet. The ratio of gossypolone to gossypol was highest in muscle (1.75), followed by intestine (1.59), stomach (1.50), kidney (0.43), liver (0.34), testis (0.28), and blood plasma (0.27). This study indicated that the retention of the (-)-gossypol enantiomer is dependent on dietary concentrations and that the oxidative conversion of gossypol to gossypolone occurs more actively in the digestive tract and muscle than in other tissues in rainbow trout.  相似文献   

Symbiotic dinitrogen fixation - its dependence on plant nutrition and its ecophysiological impact     

Konrad Mengel 《植物养料与土壤学杂志》1994,157(3):233-241

The cultivation of symbiotic legumes and the consequent small uptake of nitrate by the host plant depresses soil pH and impairs subsequent legume growth. The rate of soil pH decline depends on the soil H⁺ buffer power, climatic conditions, soil permeability, and on the kind of legume cropping. It is shown for some leguminous crop species from the temperate climate that in many cases the N₂ fixation performance of Rhizobium/Bradyrhizobium symbiosis is more dependent on the growth conditions of the host plant than on the nitrogenase potential of the bacteroid. This is true for the supply of the host plant with phosphate, potassium and water as well as for light intensity. Nitrogen deficiency of the host plant because of insufficient nitrogenase activity was observed at low soil pH where nodulation and the development of the nitrogenase activity were delayed. Nodulation and nitrogenase activity are suppressed by high levels of available nitrogen in the soil. There are indications that the nitrogenase activity is very flexible and adjusts to the demand of the host plant. The mechanism of this regulation is not yet understood.  相似文献   

Professor Dr. phil. Dr. h.c. Hans Linser zur Vollendung seines 75. Lebensjahres     

Konrad Mengel 《植物养料与土壤学杂志》1982,145(3):227-228

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Effect of Geotrichum candidum protein substitution in pelleted fish feed on the growth of rainbow trout (Salmo gairdneri Rich.) and on utilization of the diet     

Konrad Dabrowski  Stephen Hassard  John Quinn  Tony J. Pitcher  A.M. Flinn 《Aquaculture (Amsterdam, Netherlands)》1980,21(3):213-232

Three experiments were conducted with rainbow trout to determine if Geotrichum candidum GC single cell protein could replace 100, 75 or 50% of fish meal in a pelleted diet. When the fish meal was completely replaced by GC the fish growth was retarded after 3 weeks of the experiment. With the larger fish (individual weight 47–54 g) in the short trial there were significant differences between fish fed the control diet (fish meal) and those fed the 75% substitution of GC diet. The most remarkable differences in fish growth appeared in a 42-day trial with small fish (5 g individual weight) when fish groups fed diets with 0.50 and 75% replacement gave significantly different results (P < 0.05), being 93,9, 46.6 and 34.2% gain, with feed coefficients of 1.49, 2.77 and 3.67, respectively. With large fish fed diets with 0,50 and 75% GC replacement, apparent digestibility of protein was 64.7, 68.2 and 37.5%, but fat digestibility was 79.5, 91.1 and 81.0%, respectively. No significant differences in amounts of free plasma amino acid (PAA) were found between rainbow trout fed diets with 0 or 50% substitution, but there was a marked decrease in PAA in the group fed the diet with 75% GC substitution. Analysis of chosen heavy metals was made on diets, fish and faeces, and Cu in particular was found not to be accumulated in the fish body.  相似文献   

Supplementation of maca (Lepidium meyenii) tuber meal in diets improves growth rate and survival of rainbow trout Oncorhynchus mykiss (Walbaum) alevins and juveniles   总被引：2，自引：0，他引：2  

Kyeong-Jun Lee  Konrad Dabrowski  Jacques Rinchard  Carlos Gomez  Leszek Guz  & Carlos Vilchez 《Aquaculture Research》2004,35(3):215-223

Maca tuber meal is used in fish diet formulations in Andean trout culture and knowledge of its effects on fish growth is paramount to healthy human food production. In the first experiment with rainbow trout alevins (0.096±0.002 g), starter diets were offered from first feeding until 15 weeks. We formulated high protein content (～60%) semi‐purified starter diets supplemented with 0%, 5%, 10%, or 15% maca tuber meal (control, M‐5, M‐10, and M‐15 respectively). The second feeding trial was conducted with juveniles (1.56±0.02 g) fed one of three diets (control, M‐15, and commercial) for 8 weeks. In the first experiment, fish fed M‐10 and M‐15 diets exhibited significantly higher growth rates than the other dietary groups. Survival was significantly improved in the groups fed diets supplemented with maca tuber meal (60.0–69.2%) in comparison with the group fed a control diet (21.7%). The second experiment showed a higher growth rate in the M‐15 group compared with the control and a commercial diet fed group. Leucocyte numbers were increased by dietary supplementation of maca tuber meal. The findings of the present study suggest that a maca tuber meal inclusion at least 5% improves growth rate, feed utilization, immunity by increased leucocyte number, and survival of rainbow trout alevins and juveniles.  相似文献   

Rearing of coregonid (Coregonus schinzi palea Cuv. et Val.) larvae using dry and live food: III. Growth of fish and developmental characteristics related to nutrition     

Konrad R. Dabrowski  Sadasivam J. Kaushik 《Aquaculture (Amsterdam, Netherlands)》1985,48(2):123-135

Data from 2 years of experimentation on rearing of coregonid larvae are presented. Control fish were fed live Artemia nauplii and small cladocerans and reached 188 mg and 64 mg in 1983 and 1984, respectively. Growth of fish was considerably improved when they were fed dry diets at a water temperature of 18°C in 1984. Attractants (betaine, inosine and amino acids) added to dry diets had no significant effect on fish growth and survival. In the 1984 experiment, fish fed dry diets reached 90–103 mg within 26 days and survival was 43–52%. The swim bladder was filled at a fish size of 25–35 mg and there was no difference in the morphology of the digestive tract between fish fed zooplankton and those fed dry diets.  相似文献   

An attempt to determine the survival time for starving fish larvae     

Konrad Dabrowski 《Aquaculture (Amsterdam, Netherlands)》1976,8(2):189-193

Studies were carried out on the respiratory rate of starving and fed whitefish larvae in light and darkness. Using the average respiratory rate and chemical composition of the body, the theoretical survival time for starving whitefish larvae was calculated for a given temperature during the period from hatching to 50% mortality. Applying Q₁₀ coefficients, average survival times were also calculated for starving larvae in different water temperatures.  相似文献   

Changes in contents of carotenoids and vitamin E during tomato processing     

Seybold C  Fröhlich K  Bitsch R  Otto K  Böhm V 《Journal of agricultural and food chemistry》2004,52(23):7005-7010

The aim of this study was to investigate the effect of different types of tomato processing on contents of lycopene, beta-carotene, and alpha-tocopherol. Samples of tomato sauce, tomato soup, baked tomato slices, and tomato juice were taken at different times of heating, respectively, after each step of production. HPLC was used to analyze contents of carotenoids and vitamin E. Due to the loss of water during thermal processing, contents of lycopene, beta-carotene, and alpha-tocopherol on a wet weight basis increased. On a dry weight basis, contents of lycopene increased or decreased depending on the origin of the tomatoes used, whereas the beta-carotene contents decreased or were quite stable. In contrast to lycopene, beta-carotene isomerized due to thermal processing. The alpha-tocopherol contents significantly rose during short-term heating. The increase was not caused by release of alpha-tocopherol from the seeds containing predominantly gamma-tocopherol and accounting for 2% of total alpha-tocopherol content only.  相似文献