Review the performance of brokerage firms and their role on increasing investment trust and the degree of stock liquidity

The main goal of present study is to review the performance of brokerage firms and their role on increasing investment trust and stock liquidity degree, in this regard, the role of  brokerage firms is studied on increasing investors’ trust and stock liquidity degree by utilization of four independent variables (providing general and specific services, customer orientation, using updated technologies and using standards and managerial forms). The population is the brokerage firms in Tehran stock Exchange until end of year 2012, 107 brokerage firms in Khorasan province have been studied as samples. Tools for data collection were a questionnaire made by the researcher analyzed through SPSS software. The results indicated positive and significant relation among research  variables.Key words: the performance of brokerage firms, investment trust, stock liquidity degree

Stressed out symbiotes:hypotheses for the influence of abiotic stress on arbuscular mycorrhizal fungi

Abiotic stress is a widespread threat to both plant and soil communities. Arbuscular mycorrhizal (AM) fungi can alleviate effects of abiotic stress by improving host plant stress tolerance, but the direct effects of abiotic stress on AM fungi are less well understood. We propose two hypotheses predicting how AM fungi will respond to abiotic stress. The stress exclusion hypothesis predicts that AM fungal abundance and diversity will decrease with persistent abiotic stress. The mycorrhizal stress adaptation hypothesis predicts that AM fungi will evolve in response to abiotic stress to maintain their fitness. We conclude that abiotic stress can have effects on AM fungi independent of the effects on the host plant. AM fungal communities will change in composition in response to abiotic stress, which may mean the loss of important individual species. This could alter feedbacks to the plant community and beyond. AM fungi will adapt to abiotic stress independent of their host plant. The adaptation of AM fungi to abiotic stress should allow the maintenance of the plant-AM fungal mutualism in the face of changing climates. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00442-016-3673-7) contains supplementary material, which is available to authorized users