The rapidly increasing commercial application of metallic nanoparticles within products will inevitably enhance the amount of NPs being released into soil. Assessment of the impact of metallic... Show moreThe rapidly increasing commercial application of metallic nanoparticles within products will inevitably enhance the amount of NPs being released into soil. Assessment of the impact of metallic nanoparticles (NPs) in soil ecosystems is a necessity for ensuring their safe and sustainable application. In this thesis, we integrated exposure routes and exposure dynamics of NPs to investigate the uptake, translocation and impacts of metallic NPs in plants upon long-term exposure. We furthermore investigated the long-term impacts of NPs on the rhizosphere soil bacterial community and the potential transfer and biomagnification within the lettuce - terrestrial snails food chain. Our results demonstrate that 1) root exposure induced more phytotoxicity than foliar exposure at equal exposure concentrations; 2) the phytotoxicity and accumulation of AgNPs in plants was shape- and size-dependent; 3) nanoparticulate Ag present in AgNPs suspensions that predominantly drive their impacts on green leafy plants; 4) the dissolution of AgNPs in soil is the dominant process influencing Ag uptake and translocation in lettuce; 5) long-term exposure to high concentrations of AgNPs altered the structure and composition of rhizosphere bacterial community; 6) NPs can be transferred from lettuce leaves to snails, as associated with increased potential risks to higher trophic level organisms. Show less
As a contribution to the changing legislation and evolving societal attitudes concerning environmental issues, this project aims to enhance and manipulate the plants’ own natural defense mechanisms... Show moreAs a contribution to the changing legislation and evolving societal attitudes concerning environmental issues, this project aims to enhance and manipulate the plants’ own natural defense mechanisms against western flower thrips (WFT). Accordingly, an approach based on treatments of seeds (Solanum lycopersicum) and cuttings (Chrysanthemum morifolium) was undertaken to protect plants from their early critical young stage onwards. Known putative defense secondary metabolites were exogenously applied whereas, external application of plant hormones was explored as a means to trigger innate defense responses. Natural Deep Eutectic Solvents (NADES), as environmentally benign solvents, significantly improved the solubilizing properties of poorly-soluble insecticidal metabolites but did not enhance resistance against WFT. On the contrary, seed treatments with the ubiquitous plant hormone jasmonic acid (JA) appeared to induce cultivar dependent defenses as it only reduced silver damage in tomato cultivar Carousel. Sulfuric acid scarification, prior to JA seed incubation, significantly augmented the embryonic receptivity of a non-responsive cultivar thus, highlighting the importance of seed coat permeability. Moreover, we demonstrate that water dipping of indole-3-butyric acid (IBA)-coated chrysanthemum cuttings repeatedly reduced herbivory, both by thrips as well as by leaf miner. Show less
