Toxicity of rock meal based fertilizers towards duckweed (Lemna minor)

Abstract

The rock meal based fertilizers were evaluated for their toxicity towards duckweed (Lemna minor). Lemna minor is a standard ecotoxicological object for testing aquatic plant toxicity of chemicals including pesticides, biocides, heavy metals and variable industrial substances and mixtures. In recent years so called rock meal based fertilizers gain popularity in organic and standard agriculture.  They prove to be effective, easy to produce and available for farmers. Some of them can express additional induced system resistance activity or even direct fungicidal or insecticidal action.  Although fertilizers are considered to be safe for most the aquatic organisms, they can be toxic under certain circumstances, especially due to the fact they are used often in large amounts nearby water basins. The conducted research reveals that in registered concentrations, all of the tested products do not cause any harmful effects on lemna minor. Some of them were completely safe for the plants even in 7-fold increasing concentrations. However, some of the tested fertilizers were founded to be more toxic for duckweed in much less increasing of their concentrations.