Compartmentation of de-icing salts and structural reactions to salt accumulation in foliage of ornamental lime trees

Street greenery, as a way of mitigating pollution problems in cities and providing the inhabitants with different sorts of ecosystem services, has recently emerged as an important research and urbanization issue. However, street trees and other street vegetation are impacted by a considerable range of biotic and abiotic airborne and soilborne stress factors. Within cities of central and northern Europe, de-icing salt accumulation can seriously damage street trees and affect the landscaping contribution of some beloved ornamental trees, such as limes (Tilia specs.). The main objectives in this project are to study the de-icing salt accumulation and its effect on the foliage of lime trees (Tilia x vulgaris) and to apply this knowledge for selecting more salt-tolerant cultivars. In the framework of a collaboration with the institute of Biology from the University of Latvia (Sciex-NMS^CH. fellowship Sal-Ti), the compartmentation of salt at cell to leaf level and associated stress defense and tolerance reactions within chemically and cryo-fixed foliage material harvested in the streets of Riga is being investigated by means of different methods in light and electron microscopy. Data from these analyses will be compared to soil and foliage elemental content and to levels of visible injury, as measured after foliage harvest at the Institute of Biology of the University of Latvia. In a second phase of project, this approach is completed with histological assessments and implemented in the framework of a salt-exposure experiment performed in partly controlled conditions, using young trees from three lime tree species. The main objectives in this part of project are to better understand the tolerance differences between the three lime tree species and and thus improve the selection of resistant ornamentals, with a view to street plantations.