Morphological Evaluation of Chrysopogon zizanioides: Criterion for the Effectiveness of Phytoremediation of Mine Tailings Under Sahelian Climate

---

Résumé

Artisanal gold mining generates uncontrolled waste responsible for heavy metal soil contamination
metals, threatening both human health and agricultural productivity. Phytoremediation offers a sustainable solution
to mitigate these impacts. This study assesses the morphological responses of Chrysopogon zizanioides grown in
mine tailings under Sahelian climatic conditions. The experiment was conducted in a greenhouse using a
randomized complete block design with two treatments: polluted substrates (P) derived from cyanidation residues
and non-polluted substrates (NP) from pre-cyanidation washing. Over 18 months of growing in pot, survival rate,
tiller production, and biomass growth were monitored. A high tolerance index (TI) was recorded during the first
campaign (C1) at 85.7 ± 0.1%, followed by a decrease in C2 (71.2 ± 0.1%) and C3 (70.6 ± 0.1%). An increase in TI
was observed in C4 (79.8 ± 0.04%) and C5 (79.1 ± 0.1%). Relative water content (RWC) remained stable in NP pots
(64.2%–67.7%), with a peak at C3 (98.3%), while in P substrates it ranged between 59.2% and 69.4%. Specific root
length (SRL) showed a decline from C2 onward, indicating a shift in root architecture. Relative growth index (RGI)
revealed differentiated growth phases, although no significant differences were observed between NP and P
treatments. These morphological responses serve as early indicators of phytoremediation performance under
Sahelian conditions, even before further chemical analyses

Mots-clés

Phytoremediation - Mining residues - Morphological parameters - Vetiver - Pollution - Sahelian climate