Yamma Rose^{1, 2,}, Kone Martine³, Sawadogo Bienvenue Jocelyne¹, Maiga Guébré¹, Yonli Arsène¹, Wanko Ngnien Adrien⁴

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.