ASSESSSING THE EFFECT OF WORM CAST ON BIDENS PILOSA GROWTH IN COPPER CONTAMINATED SOIL

This study assessed the effect of worm cast on the growth of Bidens pilosa in copper contaminated soil. Different concentrations of copper solutions (0 – 200 mg/g) were applied with varying concentration of worm cast amendment (0, 10, 20, 30, and 40 g). Ten viable seeds of B. pilosa, sourced from the wild, were sown in the pots. Soil in pots without copper contamination served as the control. All treatments, A, B, C, D, E, and F, were replicated three times and arranged in Completely Randomized Design. Growth parameters including plant height, number of leaves, and stem girth were measured weekly for six weeks. The chlorophyll content of the leaves were determined immediately after harvesting where treatment D recorded the highest value in chlorophyll a of 2.53 ± 0.13 to 2.70 ± 0.03, while treatment F had the highest value in chlorophyll b of 2.36 ± 0.17 to 2.63 ± 0.05. Thereafter, plants fresh and dry weight were taken before they were analysed for N, P, and Cu content where soil without copper treatment (F) indicate better nutrient accumulation. The worm cast, soil used for planting before and after contamination were analysed for physicochemical parameters. Data obtained were subjected to statistical analysis using two-way analysis of variance (ANOVA) on SPSS 27.0. Results indicates that at control, the B. pilosa highest height value ranges from 55.83 ± 3.25 cm to the lowest value of 41.67 ± 7.75 cm was obtained. At treatment E, the highest height value of 40.33 ± 5.48 cm and the lowest value of xi 19.83 ± 18.45 cm was obtained. At treatment D, the highest height value of 39.83 ± 3.82 cm and the lowest value of 28.27 ± 14.06 cm was obtained. At C treatment, the highest height value of 50.17 ± 4.31 cm and the lowest value of 15.83 ± 27.42 cm was obtained. At B treatment, the highest height value of 42.00 ± 8.54 cm and the lowest value of 20.50 ± 3.04 cm was obtained. At A treatment, the highest height value of 46.67 ± 6.35 cm and the lowest value of 33.33 ± 13.05 cm was obtained. The results revealed that copper contamination negatively affected plant growth. However, the application of worm cast significantly improved growth performance, especially at moderate application levels, by enhancing soil fertility, stabilizing pH, and possibly reducing copper bioavailability. These findings suggest that worm cast can serve as an effective organic amendment in promoting plant tolerance and growth under heavy metal stress, thereby offering a practical approach for the remediation of contaminated soils.