Pesticides monitoring in intact plants by using non-destructive methodologies

ANALÍA IRIEL; GABRIELA CORDON; NAHUEL J BUSTOS; ZISIS VRIZAS; PARASKEYAS PARLAKIDIS; ALICIA FERNÁNDEZ CIRELLI

Workshop; 7º CONGRESO LATINOAMERICANO DE RESIDUOS DE PLAGUICIDAS; 2019

Introduction. Non-destructive methodologies for the monitoring of intact plant issues are typically based on measurements of reflectance and chlorophyll fluorescence. In environmental studies, the maximum quantum efficiency of the photosystem II (Fv/F0) and the quantum efficiency (PSII) are commonly used to evaluate the health status in plants exposed to pollutants such as pesticides, heavy metals and others. Among the advantages of the use of these methodologies can be mentioned their low cost, quick determinations and the possibility to evaluate big areas due to the possibility of applying them through satellite images. Dichlorvos (DDVP) and chlorpyrifos (CPF) are both organophosphorous pesticides mainly used in field, post-harvest treatments and animal production to control common pests that could be reach rural watercourses nearest. Objective. In this work, we explore the response of an aquatic plant, Hydrocotyle vulgaris, exposed to DDVP and CPF aqueous solutions in order to estimate which optical parameters are more sensitive to insecticide exposition.Methodology. Plants were collected from a field located at Buenos Aires province and maintained in a nutritive Hoagland solution during a week in order to acclimate them. Then, plants were immersed in DDPV and CPF solutions (concentrations 0.1 to 30 mg L-1) during 48 h. Kinetics chlorophyll emission was recorded by using a portable PAM-fluorometer (PAR-FluorPen FP 100-MAX-LM-D/BT, Photon Systems Instruments). Results were compared with control plants (without insecticide).Results and discussion. Obtained results indicated deleterious effects in the status of exposed plants. Particularly, a strong diminution in the photochemical parameters of PSII and Fv/F0, evidenced that both insecticides drastically affected the photosynthetic apparatus functioning. In all the cases, the most affected parameter was Fv/F0 where a reduction of 4%, 29% and 68% was registered for solutions of CPF (standard), CPF (commercial) and DDPV (standard), respectively. In addition, PSII was reduced in 1%, 7% and 29% for CPF (standard), CPF (commercial) and DDPV (standard), respectively. Spite of the similarities, some differences were observed in the way that energy was delivered into the plant. In this sense, for CPF treatment, an increase in the emission chlorophyll was observed while for DDPV the thermal dissipation was enhanced regarding to the control plants. Conclusions. Photosynthetic parameters of PSII and Fv/Fm have resulted a sensitive tool to describe toxicological effects on aquatic plants exposed to insecticides. Moreover, chlorophyll fluorescence kinetic measurements could represent a valuable tool to understand the mechanisms of insecticides on the photosynthetic process.Acknowledgments. This project has received funding from the European Union?s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement N° 690618 KNOWPEC.