What determines voting behavior to host the Olympic games in the Rhine-Ruhr area: a multilevel model.

This study analyzes factors influencing public support for hosting the Summer Olympics in the Rhine-Ruhr (RR) region in 2036 or 2040. Analyzing data from 14 municipalities, a multilevel model is used to account for individual and contextual factors. Despite a high overall endorsement rate of 67%, the study shows that consumer capital, pride, perception of sustainability, and historical significance significantly influence voting behavior. Surprisingly, structural factors at the municipal level do not show a significant influence. This research provides valuable insights for policymakers and organizers considering future Olympic bids in the RR region. The results emphasize the importance of effective communication to gain public support. This communication should highlight the environmental and economic sustainability of the host community, historical significance, and intangible benefits such as pride.

Chaetomium elatum (Kunze: Chaetomiaceae) as a root-colonizing fungus in avocado: is it a mutualist, cheater, commensalistic associate, or pathogen?

Plants support numerous root colonists that may share morphological characteristics with mycorrhizal fungi but may play different roles in the rhizosphere. To determine the function of one such root-colonizing fungus, Chaetomium elatum, the infectivity and composition of inoculum containing C. elatum were varied independently of and in association with the known mutualist Glomus intraradices under two light intensities. Maximum plant benefit occurred with mixtures of both G. intraradices and C. elatum and under high light intensity. Under low light intensity and in monoculture, C. elatum functioned as a weak pathogen that was able to kill host plants. Here, maximum plant mortality was associated with the highest levels of C. elatum infectivity. When G. intraradices was present, no negative impact of C. elatum was detected. Intraspecific interactions were important in predicting sporulation rates for both fungi, whereas no interspecific fungal interactions were detected. In the presence of G. intraradices, C. elatum appears to function as a "commensalistic associate," neither impacting plant growth nor sporulation by G. intraradices. Overall, C. elatum appears to be multifunctional, serving as both a rhizoplane and rhizophere fungus, opportunistically colonizing plant roots and only becoming pathogenic when resources are severely limited and intraspecific competition is high. This multifunctional strategy may be shared with other fungi that form similar structures in roots.

Comparison of Seasonal Infection of Citrus Roots by Phytophthora citrophthora and P. nicotianae var. parasitica.

Excised feeder roots from mature citrus trees located in climatically different regions were infected with zoospores of Phytophthora citrophthora and P. nicotianae var. parasitica at different times of the year under identical laboratory conditions. Zoospores encysted on and caused infection in roots from all locations year round. Both pathogens had the most encysted zoospores on roots from November to January and the least from March to May. Infection by P. nicotianae var. parasitica was consistently higher than P. citrophthora in the excised summer roots (May to September) and lower in January 1998 and November 1997. Infection by both species of Phytophthora dropped to a minimum in March when carbohydrate levels in roots were lowest. Temperature was not solely responsible for determining seasonal fluctuations of P. nicotianae var. parasitica and P. citrophthora. Root carbohydrate content also could not be correlated with seasonal infection. Other physiological or microbial factors associated with citrus roots may cause seasonal Phytophthora infection fluctuations. Infection of citrus seedling roots by P. citrophthora at 16°C reduced root starch content but not glucose compared to P. nicotianae var. parasitica, whereas infection at 30°C by P. nicotianae var. parasitica lowered root glucose but not starch content compared to P. citrophthora.

Biological control of Phytophthora root rot of avocado with microorganisms grown in organic mulches

Organic mulches colonized with microbial biocontrol agents, termed bioenhanced mulches, were tested for their ability to reduce Phytophthora root rot of avocado (Persea americana Mill.). Benomyl-resistant mutants of Gliocladium virens (KA 230-1) and Trichoderma harzianum (KA 159.2) isolated from suppressive soils and selected as efficient antagonists of P. cinnamomi were evaluated for their ability to colonize different mulches under controlled laboratory conditions. Sudangrass and a coarse yardwaste were found to be better substrates than a fine yardwaste, woodwaste or rice hulls for biocontrol agents propagules production. The most suitable conditions for colonization were an optimum temperature of 24 C, a moisture content of 20 ( per cent) for sudangrass and 30 ( per cent) for the coarse yardwaste, and a continuous light exposure during a 15-day incubation period. In the greenhouse, fresh sudangrass and coarse yardwaste colonized with G. virens and used as a surface mulch proved to be the best combination for reducing the population of P. cinnamomi in 4-liter pots containing artificially-infested soil. Healthy avocado roots made up 31-37 ( per cent) of the roots in the G. virens-mulch combinations compared to 0 ( per cent) healthy in infested controls after two months.

Regulation of nutrient transfer between host and fungus in vesicular-arbuscular mycorrhizas.

Although the overwhelming majority of non-aquatic vascular plants form vesicular-arbuscular (VA) mycorrhizal associations, the extent of colonization of the host root by any given fungal symbiont varies considerably depending on host and environmental factors. Because VA mycorrhizal fungi are obligate biotrophs, transfer of photosynthate from host to fungus may be an important factor in regulating the extent of VA mycorrhizal formation. Host metabolites must cross the plasma membrane before becoming available to the fungus. Several studies on rates of root exudation under various environmental conditions show a strong correlation between rates of root exudation and percent of root length colonized by VA mycorrhizal fungi. However, passive leakage of simple metabolites from roots as the sole means of regulating fungal colonization seems improbable for an obligate biotroph which has not yet been successfully cultured on any artificial medium. So far there has been insufficient investigation of hormone interactions between symbionts, and of the interference by the fungus in host cell wall synthesis, to evaluate the possible role of these factors in controlling growth of VA mycorrhizal fungi. Cytochemical studies of the host-fungus interface suggest modification of host plasma membrane ATPase activity as arbuscules develop, but the function of this altered activity remains unresolved. The presence of a linked P1 -photosynthate exchange mechanism on the host plasma membrane analogous to the P1 -photosynthate translocator known to exist in the outer membrane of chloroplasts remains an uninvestigated possible mechanism for balancing photosynthate demand by the fungus with enhanced P uptake.