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Due to the widespread use of silver nanoparticles (nAg) in different products, the possibility of their leakage into the environment has been increasing. It is, therefore, crucial to study the possible effects of nAg on plants as the key components of ecosystems. In the present study, the effects of different concentrations of colloidal nAg on sweet maize were investigated at the anatomic level. Using dynamic light scattering and electron microscopy, the size of the nAg was estimated less than 80 nm. After one week of treatment, thin cross sections of roots and shoots were prepared and studied by light and fluorescence microscopes. Results showed that cortex and vascular cylinder area of roots and shoots of treated plants significantly (P<0.05) decreased versus control. Significant (P<0.05) reduction in diameter of metaxylem vessels was also identified. In addition, deform cells and Ag accumulations in root tissues of treated seedlings were observed. The results of this study indicate that nAg can enter into plant root and make considerable adverse effects on the plant root anatomy suggesting that nAg can become a future emerging pollutant. [ABSTRACT FROM AUTHOR]

This study was carried out to evaluate the effects of salinity stress (16 dS m-1) on proline accumulation and expression pattern of three genes involved in the proline synthesis (P5CS, P5CR) and degradation (PDH) in the fourth and the flag leaves. The experimental treatments consisted of two levels of salinity stress including 1.6 (control) and 16 dS m-1 and three wheat cultivars, namely, Hirmand and Chamran (as tolerant cultivars) and Atrak (as sensitive). These were arranged as factorial based on a Completely Randomized Design with three replications. There was an increase in Na+ concentration and decrease in K+ concentration in salinity stress compared to the control condition in the fourth and the flag leaves of all cultivars. However, the tolerant cultivars showed lower level of Na+ concentration and higher level of K+ concentration and K+/ Na+ ratio. Seemingly, the increase in proline accumulation was due to P5CS, P5CR up-regulation and PDH downregulation. On the other hand, the higher proline degradation in the fourth leaf of the tolerant cultivars was probably due to the provision of a source for energy or nitrogen, which helped to enhance the yield of these cultivars under salinity stress. [ABSTRACT FROM AUTHOR]

Timely herbicide application is a key factor in herbicide efficiency that may provide some possibility of reducing herbicide dose. Field experiments were conducted to study the interactive effect of dose of the herbicide mesosulfuron-methyl and application timing on the control of Bromus japonicas in wheat. Herbicide application timings were based on Zadoks growth stages of wheat. An empirical model was developed for deciding herbicide dose. Relationships between herbicide dose and weed biomass were described with the standard dose-response model at each application time. Parameter estimates suggested a linear increase in parameters W0 (weed biomass with no herbicide treatment) and ED50 (herbicide dose required for 50% reduction in W0) with thermal time. A combined dose-response ( CDR) model, with W0 and ED50 being replaced by their linear relationships with thermal time, was used for weed biomass prediction. CDR was incorporated into the rectangular hyperbolic relationship to predict wheat yield with different herbicide doses and application timings simultaneously. The combined model was rearranged to give the minimum dose required to restrict weed competition and achieve an acceptable wheat yield. For example, to obtain a wheat grain yield of 4.4 kg h−1 (90% of the potential yield), the model suggests 75% of the recommended dose, if herbicide is applied prior to tillering. With delayed herbicide application to wheat jointing, the respective amount of wheat yield is achieved with herbicide rates higher than the recommended dose. The model developed in this study can be used to decide herbicide dose for controlling B. japonicus based on application timing. [ABSTRACT FROM AUTHOR]

1-Introduction Urban governance is new structure in the process of urban management that changed the centralized and traditional forms of management in cities and challenged its theoretical base. The results of this new approach in the integration of civil society, urban management and private sectors to deal with urban issues are salient. This approach looks at the system and all sectors of society as a unified body, so it can be very useful in urban management topic. Rapid population increase, that coupled with rapid urban development and urbanization, facing policy makers, official's managers and municipal system with many problems in different countries. Naturally, a huge wave of urbanization has made urban problems such poverty, migration, lack of resources, services and infrastructure, urban congestion and pollution which are significant challenges for urban management and also has hampered economic, social and cultural processes in cities. Nowadays, urban management facing with new challenges. These challenges proof the necessity of change in the structure of city management. Traditional approaches to management and planning in process of society's problems solution are not effective. Urban governance has appeared as a new strategy in process of urban management in the late 90's, after the emergence of these events and new trends in urban society. Accordingly, this study seeks to survey the challenge of urban governance and its dimensions in a country like Iran. .This study with descriptive and analytical method, try to analysis how to apply the principles governing of urban governance. To estimate this purpose, four samples of this new approach as transparency, accountability, efficiency and flexibility with several sub-indices were analyzed in fuzzy AHP algorithm, under expert opinions 2- Theoretical bases After urban management attitudes, economic and political views and scientific development and planning concept began to change, urban governance has considered in urban management process. The evolution of urban management approaches shows that flexibility, replication and accountability of government systems and acceptance of hierarchical bottom-up process are the original pressing principles are sustainable development. Literature review defining new criteria’s related to urban governance (Cronwall and gaventa,2001). They all emphasize three main elements in the process of urban conduction system: civil society, private sector and city management bodies. Governance pattern of urban development is remembered as the participatory process by which all stakeholders including government, urban management, private sector and civil society provide the tools to solve the problems of rapid urbanization. The situation in developing countries, rapid urbanization in the continuation of traditional management approaches in cities, created conditions that necessity to strengthen local governments and public and private sector participation in urban development planning. In fact, today it is recognized that solving the problems caused by rapid urbanization in these countries is possible by reformed traditional methods and use of new management approaches. Indentify the indicator and applying priciples is the most omportant fair in urban governance approch. Because with this indicatorse we could find the theories and view points. 3- Discussion One goal of this research is defining appropriate indicators for urban governance. After review the history and literature of urban governance, we selected indicators that match the Iran conditions. Because this study deals with qualitative concepts, fuzzy logic was based as a leading methodology. Then, the decision making team that contains management and urban planning experts have formed. This group were asked about their views on the criteria and sub criteria’s of urban governance with paired comparisons. In the next step, hierarchical model has drawn and the relationship between criteria’s and sub criteria’s has determined. After this stage, we constitution the primary decision matrix and then fuzzy decision matrix. FAHP model has multiple computational steps, which were conducted in this study as a hierarchical prosses. Finally, we determined the weights of urban governance criteria’s and sub criteria’s based on decision making team. 4- Conclusion This study with analytical - descriptive methodology, analysis the main urban governance criteria’s (transparency, efficiency, accountability and flexibility) and sub criteria’s by using experts viewpoints and FAHP model. The results show that, among the main indicators, performance with28% was considered as important indicators and accountability index gain the minimal weight. Between sub criteria’s, performance allocated the lowest and highest weight. So that Creativity and leadership with 88% gain the heights weight and Problem-Solving Skills with 20% gain the lowest weight. In the present study using the expert opinions, transparency and efficiency with its own secondary indicators were selected as a revolutionary indicator of urban governance. Results in data analysis using a fuzzy AHP (FAHP) showed that the main problem in urban management system is within organization problemse. We could see this topic in creativity and leadership as a sub criteries. The results showed that for move in urban governance road, we have to attention to internal organization relations. 5- Suggestions This study, according to its objects, determined and proposed indicators and their weights, for urban governance, by using expert's viewpoints. [ABSTRACT FROM AUTHOR]