University of Hohenheim

About: University of Hohenheim is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Population & Soil water. The organization has 8585 authors who have published 16406 publications receiving 567377 citations.

Carbon partitioning and below-ground translocation by Lolium perenne

Abstract: Carbon (C) balance, rhizodeposition and root respiration during development of Lolium perenne were studied on a loamy Gleyic Cambisol by 14 CO2 pulse labeling of shoots in a two-compartment chamber under controlled laboratory conditions. The losses from shoot respiration were about 36% of the total assimilated C. The highest respiration intensity was measured in the first night after the labeling, and diminishes exponentially over time. Total 14 CO2 efflux from the soil (root respiration, microbial respiration of exudates and dead roots) in the first eight days after the 14 C pulse labeling increased with plant development from 2.7 to 11% of the total 14 C assimilated by plants. A model approach used for the partitioning of rhizosphere respiration showed that measured root respiration was between 1.4 and 3.5% of assimilated 14 C, while microbial respiration of easily available rhizodeposits and dead root residues was between 0.9 and 6.8% of assimilated C. Both respiration processes increased during plant development. However, only the increase in root respiration was significant. The average contribution of root respiration to total 14 CO2 efflux from the soil was approximately 46%. Total CO2 efflux from the soil was separated into plant-derived and soil-derived CO2 using 14 C labeling. Additional decomposition of soil organic matter (positive priming effects) in rhizosphere was calculated by subtracting the CO2 efflux from bare soil from soil-derived CO2 efflux from soil with plants. Priming effects due to plant rhizodeposition reach 60 kg of C ha 21 d 21 . 14 C incorporated in soil micro-organisms (extraction‐fumigation) amounts to 0.8‐3.2% of assimilated C. The total below-ground transfer of organic C by Lolium perenne was about 2800 kg of C ha 21 . The C input into the soil consists of about 50% of easily available organic substances. q 2001 Elsevier Science Ltd. All

Influence of the gastrointestinal microbiota on development of the immune system in young animals.

Abstract: The gastrointestinal tract (GIT) of adult mammals is colonized by a complex and dynamic community of microorganisms. Most protection against potential pathogens occurs via a mucosal immune system involving mechanisms of innate immunity as well as a secondary lymphoid organ, the gut-associated lymphoid tissue (GALT). However, the bacterial community also supports its host against invasion by potential pathogens, by a mechanism called 'colonization resistance'. Young animals need time to develop both a complex bacterial community and their immature GIT immune system, and until such developments have taken place, they are vulnerable to the presence of potential pathogens in their GIT. Initial protection against invading pathogens is provided by milk and colostrum, which contain antibodies and other bioactive components. At weaning, with the introduction of solid food and deprivation of the mother's milk, the young must also cope with a rapidly changing microbiota. The colonizing microbiota not only provides colonization resistance to potentially pathogenic bacteria. It also has a major role in the development of the intestinal immune system, both in terms of GALT development and mucosal immunity, and the induction of oral tolerance. Studies using gnotobiotic animal models have revealed that the presence of even limited numbers of the indigenous microbiota may influence the GIT immune system. Regulation of the composition of the GIT microbiota, e.g. by the use of pre- and probiotics, offers the possibility to influence the development of mucosal, and also systemic immunity.

Bt cotton and pesticide use in Argentina: economic and environmental effects

Abstract: This article analyzes effects of insect-resistant Bt cotton on pesticide use and agricultural productivity in Argentina. Based on farm survey data, it is shown that the technology reduces application rates of toxic chemicals by 50 per cent, while significantly increasing yields. Using a damage control framework, the effectiveness of Bt versus chemical pesticides is estimated, and technological impacts are predicted for different farm types. Gross benefits could be highest for smallholder farmers, who are not currently using the technology. The durability of the advantages is analyzed by using biological models to simulate resistance development in pest populations. Rapid resistance buildup and associated pest outbreaks appear to be unlikely if minimum non-Bt refuge areas are maintained. Thus, promoting a more widespread diffusion of Bt cotton could amplify the efficiency, equity, and environmental gains. Conclusive statements about the technology's sustainability, however, require longer-term monitoring of possible secondary effects and farmers' behavior in maintaining refuges.

Construct Validation of a short Five-Factor Model Instrument: A Self-Peer Study on the German Adaptation of the Ten-Item Personality Inventory (TIPI-G).

Abstract: The five-factor model (FFM) is currently the predominant model in trait psychology. To meet the need for an extremely brief measure of the FFM, Gosling, Rentfrow, and Swann (2003) developed the Ten-Item Personality Inventory (TIPI), which can be admin- istered in about a minute. Here we describe the development and construct validation of a German version of the TIPI (the TIPI-G). Using a multijudge (self and peer), multiinstrument (TIPI-G and the German version of the NEO-PI-R) design, we evaluated the TIPI-G in terms of internal consistency, factor structure, convergent and discriminant validity, and coverage of the NEO-PI-R facets. Together the analyses suggest that the 10 unipolar items of the TIPI-G can provide an efficient approximation for longer measures of the FFM personality constructs. As such, the TIPI-G is recommended for research where time is limited, where the primary theoretical focus is on other constructs, or where it is desirable to reduce the testing burden on participants.

The Accuracy of Self-Reported Internet Use—A Validation Study Using Client Log Data

Abstract: The vast majority of empirical research on online communication, or media use in general, relies on self-report measures instead of behavioral data. Previous research has shown that the accuracy of these self-report measures can be quite low, and both over- and underreporting of media use are commonplace. This study compares self-reports of Internet use with client log files from a large household sample. Results show that the accuracy of self-reported frequency and duration of Internet use is quite low, and that survey data are only moderately correlated with log file data. Moreover, there are systematic patterns of misreporting, especially overreporting, rather than random deviations from the log files. Self-reports for specific content such as social network sites or video platforms seem to be more accurate and less consistently biased than self-reports of generic frequency or duration of Internet use. The article closes by demonstrating the consequences of biased self-reports and discussing po...