Atmospheric deposition to remote receptors III. Statistical analysis of precipitation data from the ILWAS-network

A statistical analysis of the precipitation data base from the Integrated Lake-Watershed Acidification Study (ILWAS) is presented. Included in this analysis are: equivalence of distributional form of the concentrations, ion pair concentration analysis, regression by site and season, precipitation type, and multiple regressions. The analysis emphasizes the ions: H, NH₄, SO₄, and NO₃. Variability in H is explained largely through SO₄ and NO₃; spatial variability for the species pairs SO₄-H, NO₃-H, SO₄-NH₄; and NO₃-NH₄ does not suggest significant differences between sites on a seasonal basis.     

Modulation of hepatic drug metabolizing enzymes and oxidative status by rooibos (Aspalathus linearis) and Honeybush (Cyclopia intermedia), green and black (Camellia sinensis) teas in rats

Rooibos and honeybush teas significantly (P < 0.05) enhanced the activity of cytosolic glutathione S-transferase alpha. A significant (P < 0.05) to marginal (P < 0.1) increase in the activity of the microsomal UDP-glucuronosyl transferase was obtained with unprocessed rooibos and honeybush teas, respectively. Oxidized glutathione (GSSG) levels were significantly (P < 0.05) reduced in the liver of all tea treated rats while reduced glutathione (GSH) was markedly increased in the liver of the herbal tea treated rats. These changes resulted in a significant (P < 0.05) increase in the GSH/GSSG ratio by the unprocessed, processed rooibos and unprocessed honeybush teas. Green and black teas markedly to significantly decreased the oxygen radical absorbance capacity in liver homogenates, respectively. Modulation of phase II drug metabolizing enzymes and oxidative status in the liver may be important events in the protection against adverse effects related to mutagenesis and oxidative damage.     

Species concepts and systematics of domesticated cereals

Summary Cultivated cereals are domesticated grasses. Wild progenitors of domestic cereals are aggressive natural colonizers and often become weedy in man disturbed habitats. Hybridization between cultivated cereals and their close wild relatives gives rise to mimetic cereal weeds that often accompany the domestic species well beyond its natural range. Similar weeds may also evolve from abandoned cultivars as a result of mutations that restore their ability for natural seed dispersal. Cultivated complexes of domestic species are typically variable. Man selects and isolates phenotypes to suit his fancies, with the result that different phenotypes of a cereal are often grown for different uses in the same village, and adjacent villages often grow different phenotypes for similar uses. Conventional species concepts do not hold for domestic species. It is proposed that wild, weed and cultivated complexes of individual domestic species be recognized respectively as subspecies. Major discontinuities in variation within the weed or cultivated subspecies are then identified as races without formal taxonomic recognition.

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Artbegriff und Systematik bei domestizierten Getreiden

Zusammenfassung Kultivierte Getreide sind domestizierte Gräser. Die wilden Vorfahren der domestizierten Getreide sind aggressive natürliche Besiedler und werden oft zu Unkräutern in vom Menschen beeinflußten Standorten. Bastardierung zwischen kultivierten Getreiden und ihren wilden Verwandten läßt mimetische Getreideunkräuter entstehen, die oft die domestizierten Arten außerhalb ihres natürlichen Verbreitungsgebietes begleiten. Ähnliche Unkräuter können sich auch aus aufgegebenen Sorten entwickeln als ein Ergebnis von Mutationen, die ihre Fähigkeit zur natürlichen Samenausstreuung wiederherstellen. Kultivierte Komplexe domestizierter Arten sind in typischer Weise variabel. Der Mensch selektiert und isoliert Phänotypen nach seinen Vorstellungen mit dem Ergebnis, daß verschiedene Phänotypen eines Getreides oft zu verschiedenen Zwecken im selben Dorf angebaut werden, und benachbarte Dörfer oft verschiedene Phänotypen für ähnliche Zwecke kultivieren. Der herkömmliche Artbegriff bewährt sich nicht bei domestizierten Arten. Es wird vorgeschlagen, daß Wild-, Unkraut- und Kulturformen einer domestizierten Art als entsprechende Unterarten angesehen werden. Größere Gruppen innerhalb der Unkraut- oder Kultur-Unterart sollten als Rassen ohne formale taxonomische Bezeichnung gehandhabt werden.

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Microbial community responses to disease management soil treatments used in flower bulb cultivation

Biology and Fertility of Soils - A number of management practices, such as soil fumigation and flooding, have been employed in efforts to control diseases and weeds in the cultivation of ornamental...     

Einfluss von konventioneller und biologisch-dynamischer Bewirtschaftungsweise auf die mikrobielle Biomasse und deren Stickstoff-Dynamik in Parabraunerden der Friedberger Wetterau

Effect of conventional and biological farming on microbial biomass and its nitrogen turnover in agriculturally used luvisols of the Friedberg plains The influence of conventional and biological farming on microbial biomass-carbon (Bio-C) and nitrogen (Bio-N) of agriculturally used fields was compared. The fields were located on luvisols of the Friedberg plains and tilled according to each system for many years. Bio-C and Bio-N were measured using the chloroform-fumigation-extraction technique. During early spring and autumn (1990) [Bio-CI% C_org] and Bio-N [%N₁] were slightly lower in sites of conventional farming than on fields tilled by biological farming. During the vegetation period Bio-C and Bio-N increased continuously in both systems. This increase, however was higher on conventional than on biological fields and may be ascribed to a higher C-input (rhizodeposition) and availability of mineral nutrients. In the soils of the biological farming system N-deficiency apparently decreased Bio-N (but not Bio-C) in spring time. Consequently the Bio-C/N-ratio increased. It seems as if plant growth affects the quality of microbes (Bio-C/N). The average turnover-time of Bio-N was about 1 year in all soils. However, the average turnover-time of Bio-C was 1.6 years, being 2 times faster in the conventional than in the biological farming system. It seems as if long-term management practices may affect the amount of labile organic matter by changing the biomass pool and its turnover rate.     

A rapid quantitative bioassay for the determination of biologically available bromacil in soils

A simple rapid bioassay is described for the determination of biologically available bromacil residues in soils. A clear aqueous extract was made from a soil fortified with a known amount of the herbicide, and similar extracts were made from samples of soil taken from plots that had been sprayed with a bromacil formulation at a rate of 4 kg ha⁻¹. Samples of these extracts were added to a suspension of the unicellular green alga Selenastrum capricornutum. The net photosynthetic oxygen production by the alga was then measured using an oxygen electrode. The results were expressed as a percentage of the oxygen production by a control suspension. The concentration of biologically available bromacil was determined by reference to a previously established dose-response curve of the percentage reduction in oxygen production against bromacil concentration. The accuracy of this bioassay was determined by comparing the results with those obtained using capillary gas-liquid chromatography. The results obtained by the two different methods showed good agreement.     

The Impact of Aquaculture Pond Engineering Design on the Returns to Shrimp Farms

The effects of pond design on the internal rate of return of a 40 ha shrimp farm is evaluated. The influence of four pond construction parameters (pond size, pond shape, levee crown size and canal bank slope) on the total amount of earth moved and construction costs is determined using an engineering design model. The bioeconomic model, MARSIM, calculates returns to farms with the design modifications. Of the four parameters, the pond shape is the most influential over the range considered (from 17% to 8%). Pond size is the second most important parameter (from 17% to 21%). Levee width and canal bank slope influence are of lesser importance (<1% change).     

Morphologisch-taxonomische Gliederung der Kultursippen vonBrassica oleracea L.

Summary There is given an account about the morphological differentiation of the cultivated types ofBrassica oleracea, their taxonomy, uses and history.

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100 Jahre Kulturpflanzen-Taxonomie

Ohne Zusammenfassung     

Die zu Würz- und Speisezwecken kultivierten Arten der GattungAllium L

Ohne Zusammenfassung