Morphometric characterization and ecotoxicological effect of lead in seed germination of Schinus terebinthifolius Raddi

Abstract

Schinus terebinthifolius Raddi is an evergreen tree found in several Brazilian biomes and used in the reforestation of degraded areas that may be contaminated by heavy metals. This research determined the morphometric characteristics and evaluated the ecotoxicological effects of lead (Pb) in the germinal development of pepper mastic (S. terebinthifolius). The moisture (%) and 12 morphometric measurements of seeds (n = 230) were determined: 1,000 seed weight, length, width, thickness, elongation in three dimensions (length, width and thickness), geometric mean diameter, surface area, volume, sphericity and bulk density. Ecotoxicological effects of lead on the germination of seed development were evaluated in eight different concentrations (0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 4.0 and 6.0 mM) in triplicate with 40 seeds per replicate. The response variables were: volume of seed germination during development, germination percentage, mean germination time and germination speed index. Pb present in low concentrations causes toxic effects that affect the percentage (0.2 mM) and germination speed index (0.4 mM). Despite these effects, they did not increase when the S. terebinthifolius was exposed to higher concentrations of Pb. Thus, it is likely that S. terebinthifolius have tolerance or physiological adaptation to Pb. However, in Pb contaminated environments, its initial establishment may be compromised or made impossible, due to this chemical stress.