Formation of wall openings in root cells of Arabidopsis thaliana following infection by the plant-parasitic nematode Heterodera schachtii

The induction and differentiation of feeding structures (syncytia) of the cyst nematode Heterodera schachtii in roots of Arabidopsis thaliana is accompanied by drastic cellular modifications. We investigated the formation of cell wall openings which occurred during syncytium differentiation. At the beginning of syncytium induction, a callose-like layer was deposited inside of the wall of the initial syncytial cell (ISC). First wall dissolutions developed by gradual widening of plasmodesmata between the ISC and neighbouring cells. As a general thickening of syncytial cell walls blocked existing plasmodesmata, other large openings were formed by enzymatic dissolution of intact walls by putative cellulase activity.     

Changes in the structure of Arabidopsis thaliana roots induced during development of males of the plant parasitic nematode Heterodera schachtii

Plant parasitic nematodes of the genus Heterodera show a high degree of sexual dimorphism, which is reflected by different nutritional demands and differences in the structure of the induced specific syncytial feeding site in the plant. The determination of the sex of the nematode Heterodera schachtii and other related species was repeatedly reported to be dependent on trophic factors, which are provided by the induced syncytia. The structural differences of syncytia induced by H. schachtii in roots of Arabidopsis thaliana were analysed at the anatomical and ultrastructural level. Syncytia of males were induced in the root pericycle. The developing syncytium then expanded into procambial or cambial cells of the vascular cylinder. Differentiated vascular elements were not included. The expansion of the syncytium triggered the proliferation of cambial and peridermal tissues, in a manner similar to secondary growth, and the formation of additional xylem and phloem elements. In comparison to syncytia associated with females, syncytia associated with males were less hypertrophied and were composed of more cells. Distinct cell wall openings were mostly found between the few strongly hypertrophied syncytial elements at the actual feeding site in the pericycle. The ultrastructure was very similar to female-associated syncytia but showed conspicuous differences in the structure and localization of cell wall ingrowths. These ingrowths were rare and weakly developed and occurred not only at the interface with xylem elements but also at the internal and external walls of the syncytia. After feeding had ceased at the end of the third developmental stage the syncytia degenerated.     

Characterization of cation exchange capacity (CEC) for agricultural land-use areas

Spatial assessment of soil properties needs conversion of point data to an area-oriented model. Methods are required that create a reproducible map. The development of a map is shown by the example of cation exchange capacity. Twenty sorption types are formed and derived from the vertical sequence of values for substrate types and are aggregated to six main types. A qualitative assessment of the main CEC sorption types is carried out with comparative ranking. The association of different substrate types on an areal soil pattern requires the identification of sorption association types. These are shown by the areal share of the main sorption types for the substrate types involved in each case. For interpreting the site parameters from the MMK (Mittelmaßstäbige Landwirtschaftliche Standortkartierung), the procedure is presented in detail. An example of the results is shown with CEC maps. Tables complement the visualization for different areas, defined by administrative or natural landscape boundaries. The application of this method for relative evaluation of CEC is demonstrated using KA5-rules. The CEC characterization of agricultural areas can be reproduced on the basis of the mapping units of soil maps with different scales (BÜK 200). The areal-specific labeling of CEC constitutes soil-related decision guideline.     

A long term study of the health status and performance of sows on different feed allowances during late pregnancy. I. Clinical observations, with special reference to agalactia post partum

Thirty nine pairs of full sibs were investigated over 6 parities in a long term study on the effects of late pregnancy feed allowance on the occurrence of agalactia post partum and on the performance of sows and piglets. A careful examination of all sows with a rectal temperature exceeding 39.5 degrees C was performed by a veterinarian within the first 48 h after farrowing. Milk-samples were taken from sows with elevated rectal temperatures and showing clinical symptoms of agalactia. During the last 15 days of gestation the sows in the control group were fed 3.4 kg daily and the sows in the experimental group 1.0 kg daily of a commercial type of diet. In 26.6% of the farrowings in the control group the sows were agalactic whereas the corresponding figure in the experimental group was 14.4%. On clinical examination udder changes were observed in a majority of the diseased sows in both groups. However, the agalactic sows in the control group were generally more affected, with lower water and feed consumption than in the experimental group. No effects of age of the sow (parity number) or length of the gestation period on the incidence of agalactia were demonstrated. The rectal temperature of agalactic sows was significantly higher than in the healthy sows already 1 day before farrowing. The agalactic sows farrowed a larger number of stillborn piglets, which indicates an early establishment of the disease. The number of weaned piglets at 6 weeks did not differ between agalactic and healthy animals. The interval from weaning to first oestrus was not influenced by agalactia in the preceding lactation.     

Chernozem—Soil of the Year 2005

The proclamation of the “Soil of the Year” was made for the first time in Germany in 2005 on occasion of the World Soil Day. Chernozems were selected for this purpose. In this paper an overview of these groups of soils is given. Chernozems are concentrated in the drought region of Central Germany. A standard profile from the core area of Chernozems developed from loess is presented with comprehensive laboratory analysis. Chernozems developed primarily upon carbonatic loess substrates under summer‐dry climatic conditions in an open park‐like landscape with isolated forest stands. The development of Chernozems began as early as the late glacial period, and they were fully developed by the Atlantikum age. The far‐reaching, uniformly thick humus horizons indicate substrate differences in the loess cover, which are partly the result of bioturbation. Within Germany, Chernozems and Chernozem‐like soils make up approx. 3% of the surface area and 5% (approx. 11,000 km²) of the arable land. The results of the Static Fertilization Experiment in Bad Lauchstädt, founded in 1902, clarify the high value of Chernozem for biomass production and the environment. Each loss due to erosion or decrease in surface area reduces the fulfillment of soil ecological functions of the soils and is comparable to a loss of animal and plant species. Therefore, soil scientists and the results of soil research must be more comprehensively implemented for soil preservation, protection, and politics. For acceptance of these goals among the general public and the political‐decision makers, the campaign “Soil of the Year” should give some thought‐provoking impulses.