Phytotoxicity of pyrethroid pesticides and its metabolite towards Cucumis sativus.

Pyrethroid pesticides residues have been frequently detected in soils and have been recognized to contribute to soil toxicity. The phytotoxic impact of pesticides was evaluated in Cucumis sativus (C. sativus) seeds. Percentage of seed germination, root elongation, shoot length and leaf length were considered as endpoints to assess the possible acute phytotoxicity of soil by the exposure to pyrethroid pesticides (cypermethrin, deltamethrin and cyhalothrin) and its metabolite phenoxybenzoic acid (3-PBA), in a concentration range between 50 and 500μgkg-1 . For germination percentage, it was only observed a negative impact when seeds were exposed to the metabolite. Cypermethrin showed impact in the three studied endpoints of seed development, while deltamethrin merely affected the root length. Concerning pigments content, it can be said that chlorophylls and total carotenoids median values increased for cypermethrin and deltamethrin. This increase was more pronounced to deltamethrin in joint effect with the organic solvent dimethyl sulphoxide (DMSO). When exposed to cyhalothrin and 3-PBA, no statistically significant differences were observed for C. sativus seeds to all the assessed endpoints of seed development and the investigated pigments content. This research brings new data concerning the relative sensitivity of C. sativus seeds to pyrethroids pesticides commonly found in agricultural facilities, as well as critical understanding and development of using C. sativus for phytotoxicity assessments efforts for pesticide exposures.