Morphological characteristics and germination of native species seeds for mineland rehabilitation in the Eastern Amazon

The lack of knowledge about seeds of native species constitutes a major challenge to their use in environmental rehabilitation activities. In this study, we analysed the morphology and germination of native species seeds found in areas close to Fe and Mn mines in the Eastern Amazon. We also evaluated the effect of scarification on seeds showing natural low germination. Seeds of 39 native species varying in ecological succession, biological cycle, and growth habits were tested. The pre-germination treatments of the seeds consisted of abrasion (mechanical scarification), immersion in sulfuric acid (90%) (chemical scarification), and immersion in hot water (100 degrees C) (thermal scarification). The results showed that (i) seed size and mass varied greatly between species of the same growth habit, particularly in shrubs and trees, as well as within species, for nine species; (ii) an overall low germination percentage for non-scarified seeds; (iii) an increment of similar to threefold in germination percentage and 11-fold in germination speed after mechanical seed coat scarification; (iv) and 17 of the 18 legume species analyzed showed low germination percentages, which indicates some type of dormancy. The size of the seeds had a low relationship with germination, being more related to the ecological characteristics of the species. After mechanical scarification, the tree species showed the greatest increase in germination compared to the other groups. The mechanical scarification can contribute to improving the performance of native species in the revegetation of mining areas in the Amazon, however, complementary studies are needed to better understand these species and optimize their use.

Automated summary

The lack of knowledge about seeds of native species is a major challenge for their use in environmental rehabilitation. In this study, the morphology and germination of native species seeds found in areas close to mines in the Eastern Amazon were analyzed. It was found that mechanical scarification can significantly improve the germination of native species.