Measurement and evaluation of the hydraulic properties of horticultural substrates

Sustainable, environmentally friendly and resource-saving water and nutrient management in horticulture requires knowledge of the suitability of horticultural substrates for each specific application. One specific element is their hydraulic performance. To meet this requirement, methods are needed (1) to measure the hydraulic properties and (2) to evaluate the hydraulic quality of the horticultural substrates. The aim of this study was (1) to test the extended evaporation method and the HYPROP systems for quantifying the substrate’s hydraulic properties (the water retention curve, the unsaturated hydraulic conductivity function, the shrinkage dynamics, the bulk density), and (2) to develop a rating framework for assessing the hydraulic suitability of the substrates. The hydraulic evaluation was split into cultivation under free drainage in the ground and cultivation in containers. The hydraulic criteria related to high-quality horticultural substrates were defined as the amount of easily plant-available water, the air capacity and the height of capillary rise. Limiting factors could be water repellency effects and shrinkage. The rating framework consists of five classes between non-satisfactory and very good. It was tested on 23 commercial horticultural substrates. Both the measurement methods for quantifying soil hydraulic properties and the evaluation procedure proved applicable.     

Brucellosis in camels

Camels are highly susceptible to brucellosis caused by Brucella melitensis and Brucella abortus. Difficulties can arise in diagnosis of camel brucellosis, especially as this disease provokes only few clinical signs in contrast to its clinical course in cattle. Because none of the commonly used serological test can be perceived as a perfect test for Brucella diagnosis in camel and most serological tests used for camels have been directly transposed from cattle without adequate validation, an incorrect diagnosis may occur when diagnosis is based on serology alone. Of imminent concern is the fact that brucellosis can be easily transmitted from animals or their products to humans mainly via milk. In many developing countries in the arid areas of Asia and Africa, camels are still the most important productive livestock for nomadic populations. Therefore, we reviewed the literatures on camel brucellosis to highlight the epidemiologic, economic and public health impact of camel brucellosis as a basis for designing effective control strategies.     

TEM/FE-SEM studies on tension wood fibres of Acer spp., Fagus sylvatica L. and Quercus robur L.

Tension wood (TW) fibres from maple, beech and oak were analysed with special emphasis on the cell wall fine structure and deposition of aromatic compounds within the gelatinous layer (GL). For this purpose, transmission electron microscopy (TEM) was applied after section staining with potassium permanganate. There was evidence for the occurrence of aromatic compounds in the GLs of fibres of all three species. Some GLs showed a concentric sub-layering. Hence, conclusions about the biosynthetic activities during cell wall formation in TW could be derived. Additional information about structural characteristics of TW fibres were obtained by means of field emission electron microscopy. High-resolution micrographs of cell walls were used for measurements of diameter and microfibril angle (MFA) of cellulose aggregates (CAG). CAG of 7 nm were observed although their diameter varied greatly in the GLs. MFA in the secondary wall of TW was slightly smaller than in opposite wood. The microscopic methods provided complementary ultrastructural and topochemical information on tension wood fibres. The subcellular localisation of aromatic compounds and the observations of the ultrastructural morphology will contribute to the understanding of origin and functionality of TW and its characteristic GL.     

Resveratrol induces apoptosis through ROS-dependent mitochondria pathway in HT-29 human colorectal carcinoma cells

trans-Resveratrol is a polyphenol found in blueberries, grapes, and wine with cancer chemopreventive properties. The low bioavailability of this compound enhances its concentration in the luminal content and becomes a potential chemopreventive agent against colon cancer. In the present study, the antiproliferative and pro-apoptotic effects on the human colorectal carcinoma HT-29 cells as well as the mechanisms underlying these effects were examined. Proliferation, cytotoxicity, and apoptosis were measured by fluorescence-based techniques. Studies of dose-dependent effects of trans-resveratrol showed antiproliferative activity with an EC 50 value of 78.9 +/- 5.4 microM. Caspase-3 was activated in a dose-dependent manner after incubation for 24 h giving an EC 50 value of 276.1 +/- 1.7 microM. Apoptosis was also confirmed with microscopic observation of changes in membrane permeability and detection of DNA fragmentation. The activity of trans-resveratrol on the mitochondria apoptosis pathway was evidenced by the production of superoxide anions in the mitochondria of cells undergoing apoptosis. In conclusion, trans-resveratrol inhibits cell proliferation without cytotoxicity and induces apoptosis in HT-29. Results of the present study provide evidence demonstrating the antitumor effect of trans-resveratrol via a ROS-dependent apoptosis pathway in colorectal carcinoma.     

Root Exudation of Organic Acids of Herbaceous Pioneer Plants and Their Growth in Sterile and Non-Sterile Nutrient-Poor, Sandy Soils from Post-Mining Sites

Nutrient-poor, sandy soils form the prevailing substrate at post-mining sites of the Lusatian region(Brandenburg, Germany) and present a challenge for vegetation development. We studied the organic acid quantity and composition of three commonly occurring pioneer plant species, the legumes Lotus corniculatus L. and Trifolium arvense L. and the grass Calamagrostis epigeios(L.) Roth, to determine if plant growth and exudation differed with(non-sterilized soil) and without(sterilized soil) an indigenous soil microbial community. We investigated whether organic acids were found in the rhizosphere and surrounding soil and whether this influenced nutrient mobilization. This study consists of linked field investigations and a greenhouse experiment. Plants were grown in the greenhouse in either sterilized or non-sterilized sandy soil from a reclamation site in the Lusatian mining landscape(Welzow Su¨d, East Germany). After seven months, the plant biomass, root morphology, organic acids, and water-soluble nutrients and root colonization with arbuscular mycorrhizal fungi(AMF) and dark septate endophytes(DSE) were analyzed. Roots of all three plants in the field and greenhouse experiments were highly colonized with AMF. Calamagrostis epigeios and T. arvense had a significantly higher colonization frequency with DSE than L. corniculatus. The quantity and composition of organic acids strongly differed among plant species, with the highest number of organic acids found for L. corniculatus and lowest for C. epigeios. The quantity of organic acids was greatly reduced in all plants under sterilized soil conditions. However, the composition of organic acids and plant growth in sterilized soil were reduced for both legumes, but not for C. epigeios, which had a higher biomass under sterilized conditions. Changes in nutrient concentrations in the field rhizosphere soil relative to those in the control were measurable after seven months. While the spectrum of organic acids and the growth of legumes seemed to be dependent on a highly diverse soil microbial community and a symbiotic partner, the grass C. epigeios appeared capable of mobilizing enough nutrients without an indigenous microbial community, and might be more competitive on sites where soil microbial diversity and activity are low.     

Evaluating Emissions of Nitrous Oxide from Cropland Soils Under Different Rotations in Mato Grosso, Brazil: A Scenario Simulation Study

Expansion of cropland involves immense land use changes, and the resulting intensified management practices have a strong influence on the functioning of the underlying soil. For instance, increased application of nitrogen (N) fertilizer is known to enhance fluxes of nitrous oxide (N₂O) from the soil to the atmosphere. The emission factor (EF) proposed by the Intergovernmental Panel on Climate Change (IPCC) assumes a linear relationship between added N and N₂O-N fluxes, but it does not account for environmental factors, such as soil properties or climate. Due to the high spatial and temporal variability of N₂O-N fluxes, mechanistic models are preferable in terms of extrapolation to larger scales. In this study, we evaluated simulated N₂O-N fluxes from soils under agricultural use in the Brazilian state, Mato Grosso, using the CANDY (Carbon and Nitrogen Dynamics) model. A control tool was developed in order to enable the simulation of 1 650 scenarios covering different sites (soil + climate) and management regimes (crop rotation + amount of applied fertilizer + sowing and harvesting dates). Results suggested that the sites had a very strong influence on calculated emissions, which is not accounted for by static EF. Furthermore, most fertilizer-induced N₂O-N fluxes derived from the scenario simulations were best described by a non-linear function. For sounder budgeting on the federal and national scale, there is still a strong need for long-term observations of continuous crop rotations and spatial distribution of soil types and their specific characteristics. The presented results provide a valuable starting point for developing further scenario simulations and adapting experimental campaigns for N₂O emission study.     

Bodenmerkmale montan-industrieller Standorte in Essen

Soil properties of coal, iron and steel industrial sites in Essen The physical and chemical soil properties of some Urbic Anthrosols derived from technogenic substrata in the study area Essen (Northrhine-Westfalia, Germany) were analyzed with special consideration of toxic elements. The sites are characterized by high contents of coarse fragments (> 2 mm) of different species and size whereby this fragments are partly porous. Bulk densities and particle densities are low due to the high contents of carbon. The sites show high pH-values with the exception of sulphur containing mining substrata, which are characterized by low pH-values in consequence of pyrite oxidation. Partly the technogenic substrata have a high content of carbon, especially of coal, before depositing. There are high contents of anorganic and organic toxic elements in some horizons due to the deposit species, e.g. high Cr-values in horizons with steel industrial slags and high PAH-values in horizons with coal tar containing material.     

Inhibition of potato tuber sprouting: Low levels of cytosolic pyrophosphate lead to non-sprouting tubers harvested from transgenic potato plants

Summary ExpressingE. coli inorganic pyrophosphatase in transgenic plants demonstrated that long distance sucrose transport is dependent on cytosolic pyrophosphate. It was speculated that removal of cytosolic pyrophosphate would impair sucrose utilization during storage of potato tubers and thereby prevent tuber sprouting. To explore this hypothesisSolanum tuberosum var. Désirée plants were transformed with a chimeric PPa gene. FollowingAgrobacterium mediated transformation, metabolite and carbohydrate contents of growing and stored tubers were measured. There was a large accumulation of soluble sugars and a decrease of starch at all developmental stages investigated. The PPase activity in PPaII tubers was parallel with a decrease of PPa, an increase of fructose-2,6-bisphosphate and an increase of UDP-glucose. As expected the amount of hexose-6-phosphates and glycolytic intermediates decreased. As a consequence PPaII tubers did not sprout even after a prolonged storage period of two years. Since the energy status of PPaII tubers is unaltered inhibition of sprouting is most likely due to reduced sucrose export and its subsequent utilization.