Good photosynthetic features and a favorable water regimes of woody plants improve their survival and remediation potential under unfavorable ecological conditions. Accordingly, we here present results of testing plant tolerance of Pb, Cd, Ni, and diesel fuel based on gas exchange parameters and WUE of four poplar and two willow clones grown in a greenhouse on soil culture. Photosynthesis and transpiration of plants grown on soils with individually applied heavy metals decreased significantly, but this was less obvious in the case of Cd treatment. A heavy metal mixture in the soil induced significant reduction in photosynthesis (by more than 50%). Diesel fuel as the only pollutant in soil caused very strong and significant inhibition of photosynthesis and transpiration of willow clones. The results indicate genotypic specificity of all investigated physiological parameters and mark poplar clones as very useful in phytoextraction technology for the bio-cleaning of chemically polluted soils.

Fast growing woody plants represent effective tools for cadmium (Cd) extraction during remediation of low to medium Cd contaminated soils. Poplars are good candidates for this task because of their rapid growth rate, high biomass yield, and adaptability, as well as the availability of well-characterized clones/ genotypes with various anatomical and physiological traits. The present study evaluates the potential of Populus deltoides (clone B-81) and Populus × euramericana (clone Pannonia) for phytoremediation of Cd contamination in soil. Poplar clones were analyzed for (1) plant growth response to Cd contamination, (2) Cd accumulation, translocation, and partitioning between plant organs, and (3) morphological, anatomical and physiological responses to Cd stress as a function of biomass production. Plants were cultivated in soil moderately contaminated with Cd (8.14 mg kg-1 soil) under semi-controlled conditions for six weeks. Our results suggest that P. × euramericana and P. deltoides clones respond differently to Cd contamination. Biomass production and morphological characteristics were more negatively affected in P. × euramericana than in P. deltoides plants. However, most examined leaf structural parameters were not significantly affected by Cd. In most cases, photosynthetic characteristics and gas exchange parameters were affected by Cd treatment, but the levels and patterns of changes depended on the clone. High tolerance to applied Cd levels, as estimated by the tolerance index, was observed in both clones, but was higher in P. deltoides than P. × euramericana (82.2 vs. 66.5, respectively). We suspect that the higher tolerance to Cd toxicity observed in P. deltoides could be related to unchanged proline content and undisturbed nitrogen metabolism. Following treatment, 58.0 and 46.7% of the total Cd content was accumulated in the roots of P. × euramericana and P. deltoides, respectively, with the remainder in the stems (18.2 and 39.9%) and leaves (23.8 and 13.4%). In summary, P. deltoides displayed better phytoextraction performance under Cd exposure than P. × euramericana, suggesting its potential not only for Cd phytostabilization, but also phytoextraction projects.

The spread and occurrence of the oak lace bug Corythucha arcuata out of its natural distribution area across European and Asian countries has been reported during the past decades. The ecological and economic significance of oak stands and the vulnerability of plants to various abiotic and/or biotic factors requires in-depth knowledge of plant-pest interaction. The present study examined the influence of C. arcuata feeding on the photosynthetic characteristics and gas-exchange parameters, mineral nutrient concentrations and defense mechanisms (the activities of some antioxidant enzymes) of leaves of pedunculate oak. The rate of photosynthesis, transpiration and stomatal conductance were lowered by 58.84, 21.66 and 35.71%, respectively, in comparison to non-infested plants. The concentrations of photosynthetic pigments and activities of antioxidant enzymes, catalase and ascorbate peroxidase, were affected by the presence of C. arcuata. To our knowledge this is the first paper providing a report on the physiological responses of Quercus robur plants exposed to C. arcuata infestation. Understanding the impact of pests, such as the invasive species C. arcuata on physiological processes and vitality of young plants and plant responses, could provide a foundation for efficient preservation of oak forests endangered by the oak lace bug.