Seed germination bioassay for toxicity evaluation of different composting biodegradable materials

In this paper we evaluated the ecotoxicity of the compost obtained after 90 composting days of six different types (compositions or thickness) of the biodegradable materials, using seed germination bioassay. Seeds of 'White Icicle' radish (Raphanus sativus) were sown on filter paper moistened with different concentrations of compost extract (25%, 50%, 75%, 100%) and these were compared with the control (100% distilled water) for each type of material. After incubation, germinated seeds were counted (G) and root growth (L) measured. Germination index (Gi) was calculated: (Gi ) = G / G0 x L / L0 x100, where G0 and L0 are values obtained using distilled water (control). Taking into account the composition of the materials R1-R7, no direct correlations with that could be found; however it is a clear conclusion that it is a direct correlation of phytotoxicity with the content of the compost extract, all samples being more toxics than the control.