Phytotoxic Effect of Landfill Leachate with Different Pollution Indexes on Common Bean

The leachate pollution index (LPI) represents a tool to assess the pollution potential of a leachate, on a scale from 5 to 100. However, the significance of the LPI number in terms of a particular phytotoxic effect has not been investigated. The aim of this work was to determine if the LPI is also an appropriate tool in relation to the biological significance of a phytotoxic assay using the common bean plant (Phaseolus vulgaris L.) in a greenhouse scale test. Two different leachates were used in this study: one from Guanajuato (GUL) and another from Toluca (TOL); the calculated LPIs were 34.8 and 18.4, respectively. Leachate dilutions of 25, 50, and 75 % were used; undiluted leachate (100 %) was also used, and an enriched mineral solution was used as the control. Our findings indicate that when using concentrated leachate, the LPI was not directly related to the recorded phytotoxic effect (grain yield was significantly reduced by TOL leachate); however, when only using diluted leachate (25 %), the LPI was directly related to the effect. These findings suggest that for diluted leachates, leachates with higher LPIs are likely to exert a more detrimental effect on the common bean than leachates with lower LPIs.