Germination and early seedling growth in four Plantago species in response to Zn, Cu and Fe

Heavy metal contamination is an increasingly pressing global ecological concern adversely affecting plant growth. Phytoremediation is an eco-friendly and low-cost approach to help solve this problem by using plants to remove metals. This study aimed to evaluate the phytoremediation potential of four Plantago species, exposing them to different concentrations (0, 150, 300, 600 and 900 ppm) of zinc, copper, and iron during germination and early seedling growth. These are generally the phases of the plant life cycle most sensitive to stress. The germination percentage (GP), mean germination time (MGT), radicle, hypocotyl and cotyledons length, biomass, water content and tolerance index (TI) were recorded under controlled conditions. The results indicated that metal-induced stress significantly reduced GP, increased MGT, and inhibited seedling growth with increased metal concentration. The relative toxicity of the tested metals could be ranked as Fe > Cu > Zn. Regarding the Plantago species, P. tunetana and P. lanceolata could be considered highly tolerant, P. albicans moderately tolerant, and P. afra low-tolerant to metal toxicity during germination. Therefore, P. tunetana and P. lanceolata present an excellent potential for phytoremediation of metal-contaminated zones.