A laboratory experiment was conducted to study the effect of water extracts of urban solid waste compost (USWC) of different seasons on germination and growth parameters of Lepidium sativum L.. Four USWC produced in spring, summer, autumn and winter were selected .Their water extracts of 100, 30, 10, 3, and 0% concentrations was prepared by diluting the original water extract of 100% concentration as five treatments with three replications and analyzed statistically as a completely randomized design. Results showed that maximum germination percentage was noted in 0% (control) and minimum in 100% concentrations. Highest radicle length was noted in 0% and 3% and lowest in 100% concentrations. Similar results were noted in plumule length. Result of different USWC water extract concentrations showed that water extract concentration of 10% resulted in 42 and 55% reductions in germination percentage and germination growth rate, respectively, compared to 100% concentration. Whereas, 3% USWC water extract concentration resulted in radicle and plumule lengths decrease by 72 and 59%, compared to 100% concentration. Our results indicated that different seasonal USWC prepared were not processed completely and as they are not fully matured, they contain high soluble organic compounds, imposing high toxicity during germination and early seedling growth of Lepidium sativum L.

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