The effect of two cadmium concentrations (10-5 M and 10-4 M) on growth, Cd accumulation and within-plant distribution, proline (Pro) content, and the activity of superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and glutathione peroxidase (GSH-Px) was examined in leaves and roots of poplar plants. Symptoms of Cd toxicity were evident in Cd-treated plants: stunted growth (plant height and biomass), decreased root length, and chlorosis of young leaves. Stem and leaf growth was more affected than root growth. The decreased photosynthetic activity of treated plants may have been due to lowered chlorophyll synthesis. The activity of SOD, CAT, GST and GSH-Px was altered, as was Pro accumulation. The increment of pollutant concentration in the nutrient medium was associated with higher Cd accumulation in plants. Cd in roots was ~40 times higher than in leaves and stems of plants exposed to 10-5 M Cd. Although Cd accumulation in roots was high, the potential use of this hybrid poplar for remediation of Cd-contaminated sites seems low. This is because, apart from the described growth disturbances, translocation of Cd from roots to aboveground parts is low.
In order to determine their phytoextraction potential, four clones of Salix (1. Salix alba – clone 68/53/1; 2. Salix alba – clone 106/54/0; 3. Salix matsudana – clone SM 4041; and 4. Salix nigra – clone 0408) were exposed to elevated concentrations of Cd, Ni and Pb-EDTA in a water culture solution. The translocation ratio to upper plant parts was very low for all applied heavy metals and, therefore, the metal uptake was restricted to the roots, especially regarding Pb. The ability of the clones to extract and translocate Cd, Ni and Pb differed depending on the quantity of metal content in the nutrient solution and of the willow genotype. The ability of the investigated clones to accumulate Cd in leaves is to our knowledge among the highest so far recorded compared to other hydroponic trials in literature. The preference for Cd-stimulated root growth was determined. This genotype-specific response could be part of a mechanism for Cd resistance.
The results of research into leaf stomatal variability of five European beech provenances originating from Austria, Bosnia and Hercegovina, Germany, Romania and Serbia are presented in this paper. Aim of the study was to investigate how stomatal traits of provenances originating from different environments change in response to drought stress and to assess the phenotypic plasticity of the stomatal features investigated. The study was conducted during two different years, characterized by contrasting weather conditions (2010 and 2011). Two-way ANOVA revealed that provenances differ significantly in terms of stomatal density (SD), width of stomatal aperture (Wb), potential conductance index (PCI) and relative stomatal pore surface (RSPS), during both seasons. In a dry year (2011) all provenances significantly increased stomatal density by between 16.1% (Hasbruch – DE) and 21.9% (Cer – SRB). Guard cell length (LA) was not statistically different among provenances in either year (2010 and 2011), even though LA decreased in the dry year (2011) in all provenances. Reaction norms were steep in most of the parameters suggesting the possibility of a plastic response of provenances toward changes in soil water regime, influenced by the prevailing weather each year. Phenotypic plasticity indices were the highest in regards of SD, PCI and RSPS, indicating that these traits would be good candidates for improvement in breeding programs aimed at selection of drought resistant.
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