Germination and initial growth of three legume species on managed mine substrate: effects on biomass allocation and nodulation¹

Germinação e crescimento inicial de três espécies de leguminosas em substrato de área minerada: efeitos na alocação de biomassa e nodulação

ABSTRACT

This study evaluated the germination, initial growth, biomass allocation, and association with nitrogen-fixing bacteria of three shrub legumes from rupestrian grassland, growing on bauxite mine substrates. The germinability of Senna reniformis, Chamaecrista mucronata and Centrosema coriaceum was evaluated in mine substrate after chemical and mechanical scarification. Plant survival and growth were evaluated on four substrates: mine substrate, mine substrate with the addition of 6.7% of topsoil from ferruginous rupestrian grassland, mine substrate with 3.3% of commercial substrate, and 1:1 mixture of mine and commercial substrate. Both scarification methods increased germinability of the three species. Inoculation of mine substrate with topsoil did not enhance plant nodulation. However, the moderate increase in the fertility, achieved by the adding 3.3% of commercial substrate, favored the nodulation. The 1:1 mixture of substrates increased the total plant biomass but reduced root biomass allocation and nodulation, which could reduce the success in the restoration of degraded areas.

Keywords:
Fabaceae; mine waste; nitrogen fixation; post-mining restoration; topsoil