Assessment of Herbicide-Utilizing Fungi in Agricultural Soil of Nigeria Derived Savannah Agroecological Zone

There has been an upsurge in herbicide usage in the Derived Savannah agro-ecological zone of Ni¬geria. To gauge the possible fate and effects of herbicides, soil fungal response, and capacity to utilize the herbicides, glyphosate, atrazine, 2.4-D, and paraquat were assessed. Soil culturable total fungal (TF) and herbicide-utilizing fungal (HbUF) populations were assessed using the soil dilution plate method on PDA and herbicide mineral salt agar (HbMSA). The effect of herbicides on fungal growth appearance, mycelial extension growth, and sporulation was assessed on HbMSA. Results showed that TF and glyphosate, atra¬zine, 2,4-D, and paraquat utilizing fungal (GUF), (AUF), (2,4-DUF) and (PUF) populations were 1.3×104, 1.7×102, 2.1×102, 7.0×10, and 2.3×10 cfu/g of soil, respectively. Eleven fungal species belonging to seven genera (Aspergillus, Penicillium, Trichoderma, Chaetomium, Rhizopus, Mucor, and Botryodiplodia) were isolated with Aspergillus constituting 50% of soil fungi. Two species of fungi, Aspergillus sp. and Chaeto¬mium sp., were identified as HbUF in soil. Herbicides caused delayed growth appearance and sporulation of HbUF. The mycelial extension growth rate of HbUF generally decreased with increased concentrations of herbicides. Except for 2,4-DUF, which took a reverse trajectory, spore quantity increased with increased concentration of herbicides for GUF, AUF and PUF (P ˂ 0.05). The low population and growth inhibition of HbUF indicates the possible slow rate of degradation of herbicides, therefore increased chance of envi¬ronmental pollution.