Accumulating behaviour of Lupinus albus L. growing in a normal and a decalcified calcic luvisol polluted with Zn

Lupinus albus L. is a leguminous plant that is starting to generate interest for the phytoremediation soils showing intermediate metal pollution. Among these metals, Zn causes major phytotoxicity problems and is common in polluted soils of central Spain. The purpose of this study was to explore the nutritional behaviour of this plant species towards increasing Zn concentrations in two calcic luvisol soils: a normal basic soil and a decalcified acid soil. For this purpose the effects of different Zn concentrations on mineral nutrition, growth, nodulation and nitrogenase activity of nodulated Lupinus albus cv. Multolupa plants has been investigated. A 12-week trial was performed in pots under greenhouse conditions. In each soil, four replicate pots were set up per treatment (100, 150, 300, 500 and 700 ppm Zn). Seeds were inoculated with a Bradyrhizobium sp. (Lupinus) strain ISLU-16.

Statistical analysis of data revealed significant effects of soil Zn on grown, plant mineral composition and nodulation. Lupin growth was better in acid soil than in basic soil with the low dose of Zn applied, although plant growth in acid soil was severely affected from 300 ppm Zn, where the pH of the soil was 4.7. Zn application produce nutritional imbalances, especially with the higher dose added. Most of Zn accumulation occurred in the roots in both types of soils. In acid soil, lupin absorbs high amounts of Zn in both root (4650 ppm) and aerial part (3605 ppm), when the doses of Zn applied was 300 ppm. This feature permits Lupinus albus cv. Multolupa to be considered as potential phytoremediator and also for the revegetation of degraded landfill areas with slightly acid or neutral soils polluted with Zn.