engleski

ECOFUN-MICROBIODIV: an FP7 European project for developing and evaluating innovative tools for assessing the impact of pesticides toxicity on soil microbial diversity and functions

Introduction Soil is hosting a tremendous microbial diversity playing a key-role in a number of soil ecosystemic services including nutrient cycling, filtering, ... The European Soil Framework Directive clearly identifies agricultural practices, including pesticides, as a major threat for soil biodiversity. In order to guarantee minimum effects of pesticide application on soil microbes, pesticide registration at EU level (Regulation 2006/388) considers the toxicity of pesticides onto non target soil microbes by relying on carbon- and nitrogen-mineralization tests (OECD 216, 217). These tests do not provide a comprehensive assessment of pesticides soil microbial toxicity. Thus more comprehensive tools are required to reliably estimate the toxicity of pesticides onto soil microbes. ECOFUN-MICROBIODIV is a SEE.ERA.NET-funded project aiming to develop and evaluate innovative tools to estimate the impact of low-dose herbicides (sulphonylureas) on soil functional microbial diversity. The project is based on an interdisciplinary approach conducted at different scales (from pot to field experiments) in order to test the impact of chemical weed control on ecosystem services in a corn field. Material and methods The experimental design was made on one side of a field experimentation conducted in a full randomized block pattern conducted in Serbia (5 blocks of (6 m x 5 m) per treatment) in which maize (Zea mays variety NS640) was cropped treated with 1x, 2x and 5x times the recommended dose (80 g a.i. ha-1) of nicosulfuron (ACCENT®, 750 mg kg-1) or not treated with this herbicide (Tier II). On the other side, a pot experiment conducted in control conditions in greenhouse was carried out in France using the same crop treated with higher concentrations of nicosulfuron x10, x100 and x1000 or not treated (5 replicates were done per treatment) (Tier I). Five repeated cycles were done in the greenhouse. This complete experimental design from pot to field experimentation led us to test two tiers scenario for toxicity assessment of nicosulfuron on soil microbial communities, Tier I being representative of toxicity assessment under extreme exposure schemes while Tier II is representative of a more realistic exposure scenario. Agronomical parameters were recorded for both experiments. For the field experimental yield of crop was measured and weeds development was monitored. Weeds growing in the plots were identified using morphological traits and seeds collected to test for nicosulfuron resistance. For the greenhouse experiments, root and shoot biomass of corn plants were recorded at the end of each culture cycle. Soil and corn root sampling was carried out all along the corn culture performed in the field experiment (at 2, 7, 14, 28, 56 and 116 days) and at the end of each culture cycle for the pot experiment. Soil was sieved to two mm mesh. Soil and root were frozen and shipped to partners in dry ice for further analyses. The fate of nicosulfuron was monitored in soil by HPLC-MS following an accelerated solvent extraction (ASE) system (ASE 200 ; Dionex, Sunnyvale, CA, USA) as suggested earlier (Degenhardt et al. 2010). The impact of chemical weed control is estimated using standard methods aimed at studying the abundance (ISO14240:2), diversity (ISO/TS29843-1), and the activity (TS29843-1) of the soil microflora. In addition, new methods based on direct soil DNA extraction (ISO 11063) (Petric et al. 2011) and further amplification by polymerase chain reaction (PCR) is applied to determine the impact of sulfonylurea on (1) the global structure and abundance of both fungal and bacterial communities and (2) the structure, abundance, and activity of the functional communities involved in C and N cycling as well as in the formation of endomycorhizal symbiosis. Root colonization by arbuscular mycorrhizal fungi was estimated on slides of trypan blue coloured roots fragments according to McGonigle et al., (1990). Results A synthesis of the results obtained so far within the framework of the ECOFUN-MICROBIODIV project will be presented (Martin-Laurent et al. 2013, Karpouzas et al. 2013). It will include a specific focus on the ongoing development of new ISO project standard “Estimation of the abundance of selected microbial gene sequences by q-PCR from soil DNA, ISO17601” resulting from the ECOFUN-MICROBIODIV initiative. A brief summary of the ongoing international ring test to evaluate the performances of ISO 17601 will be shown as well.

pesticides; soil; microbial diversity; microbail functions

nije evidentirano