ABSTRACT
Microplastics are contaminants in soil ecosystems that alter biophysical processes, affect plant growth, ecosystems and humans in the long run.This study was conducted to investigate the impact of microplastics on the growth and development of Zea mays (maize).Composite soil samples were collected from the Wellspring University farm from 0-10 cm depth. Physicochemical properties were assessed before maize seed sowing. Three soil weight categories (20kg) were treated with 30g, 20g and 10g microplastics. Soil physicochemical properties and heavy metal content in maize plants were analyzed. Morphological parameters, microbial counts, and microorganism identification were conducted. FTIR analysis was carried out in selected plant parts.The result showed that, pH ranged from 5.00 to 6.70; with electrical conductivity from 70 to 158 µS/cm. Organic carbon and organic matter were also present, with total nitrogen from 0.06 to 0.19 µS/cm. The average phosphorus content was between 0.63 and 3.73 mg/kg. The clay content ranged from 10.10 to 15.0 %, while the silt content was between 0.10 and 3.0 %.The concentrations of heavy metals in plant parts were within WHO standard limits of 425.5 and 500mg/kg for iron and 500mg/kg for copper, but above the limits of 40, 60, and 350mg/kg for zinc and magnesium.
The plant had various leaf sizes and heights, with chlorosis and necrotic activity ranging from 0.33 to 2.67, and a range of 1.33 to 6.33, respectively. Soil samples showed a total bacterial count (TBC) of 2.00×103 cfu/ml to 7.60×104 cfu/ml and a total fungal count (TFC) of 4.00×103 cfu/ml to 2.20×104 cfu/ml. Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Staphylococcus epidermidis, Proteus mirabilisand Bacillus cereus had percentage occurrences of 44.31, 21.17, 9.12, and 3.26%, respectively. Penicillium notatum was the most
prevalent, while Fusarium spp was the least prevalent. The study utilized FTIR analysis of maize plant parts to identify compounds, focusing on the mid-IR spectrum for sample analysis. This study revealed microplastics were absent due to possible factors such as large size of microplastics, making plants unable to absorb the microplastics. Although microplastics were not detected in plant parts, its presence in soil proves that there is potential for it to be absorbed by plants and hence the need to prevent its release into the environment to avoid human health impact.
