Table of Contents
Greener Journal of Agricultural Sciences
ISSN: 2276-7770
Vol. 16(2), pp. 89-93, 2026
Copyright ©2026, Creative Commons Attribution 4.0 International.
https://gjournals.org/GJAS
DOI: https://doi.org/10.15580/gjas.2026.2.061326087
*1Department of Biology, Shehu Shagari College of Education, Sokoto, Nigeria.
2Department of Biology, Federal College of Education Gidan Madi, Sokoto, Nigeria.
Acha (Digitaria spp.) is an indigenous cereal widely cultivated and consumed in Northern Nigeria, valued for its nutritional quality, drought tolerance, and cultural significance. Despite its importance, Acha production is constrained by seed-borne fungal infections that reduce seed viability, compromise grain quality, and threaten food safety. This study aimed to isolate and morphologically identify fungal pathogens associated with diseased Acha seeds collected from six locations in Sokoto State. Diseased seeds were purposively sampled from markets and farms, surface-sterilized, and subjected to fungal isolation using the blotter and potato dextrose agar (PDA) methods. Fungal isolates were characterized based on colony morphology, pigmentation, and microscopic features. Results revealed that Aspergillus spp. (60.5%) and Fusarium spp. (42.2%) were the most prevalent fungi, followed by Penicillium spp. (24.3%), Rhizopus spp. (18.9%), and Curvularia spp. (15.1%). The distribution of fungal genera varied across locations, with Aspergillus and Fusarium dominating in all sampled areas. The findings indicate a high burden of seed-borne fungi in Acha, underscoring the need for improved postharvest handling, proper drying, and hygienic storage practices to minimize fungal contamination and mitigate risks to seed quality and food safety.
Article No.: 061326087
Type: Research
Full Text: PDF, PHP, HTML, EPUB, MP3
DOI: 10.15580/gjas.2026.2.061326087
Accepted: 18/06/2026
Published: 22/06/2026
Armiya’u Muhammad Amin
E-mail: armeeya@gmail.com
Tel: +234(0)8132550545
Keywords: Acha, Digitaria spp., seed-borne fungi, fungal isolation, morphological identification
Acha (Digitaria spp.), commonly known as fonio, is one of the oldest indigenous cereals cultivated in West Africa and serves as a vital staple food crop in Northern Nigeria due to its high nutritional value, cultural importance, and remarkable adaptability to marginal environments (Akinola et al., 2018; Diouf, 2003). Fonio is recognized for its rapid maturation, ability to thrive in poor soils with minimal inputs, and notable tolerance to drought stress, making it a climate-resilient cereal of considerable agronomic significance in arid and semi-arid regions (Amadou et al., 2017).
Despite its contributions to food security and rural livelihoods, Acha production is constrained by several biotic and abiotic stresses, among which fungal contamination of seeds during crop growth and storage remains a major concern. Fungal infestation not only diminishes seed viability and grain quality but also results in significant economic losses for producers and traders. Additionally, some fungi produce toxic secondary metabolites, known as mycotoxins, which pose serious health risks to humans and livestock when contaminated grains are consumed (Hell et al., 2000; Sharma et al., 2019).
Seed-borne fungal pathogens have been widely reported across various cereal crops, with genera such as Aspergillus, Fusarium, Penicillium, Rhizopus, and Curvularia frequently isolated from grains (Ogunsola et al., 2019; Leslie & Summerell, 2006). These fungi can cause seed discoloration, reduced germination, and deterioration of stored grains under favorable environmental conditions, with some species capable of producing potent mycotoxins such as aflatoxins and fumonisins (Bandyopadhyay et al., 2007).
Although seed-borne fungi and mycotoxin contamination have been documented for major cereals in Nigeria, research specifically addressing the diversity and incidence of fungal pathogens affecting Acha seeds, particularly in Sokoto State—a major production hub—is limited (Sambo et al., 2023). This knowledge gap constrains the development of targeted seed health management strategies in the region.
To address this shortfall, the present study aims to isolate and morphologically identify fungal pathogens associated with diseased Acha seeds collected from selected locations in Sokoto State. The findings will provide essential baseline data on the fungal species complex associated with Acha seed deterioration, which is crucial for developing effective postharvest management, seed treatment protocols, and strategies to mitigate both quality loss and health risks.
Study Area
The study was conducted in Sokoto State, located in North-Western Nigeria (latitude 12°03′N, longitude 5°12′E). The state is characterized by a semi-arid climate with low rainfall and high temperatures, conditions under which Acha (Digitaria spp.) is widely cultivated. Samples were collected from selected farms and markets in areas recognized for high Acha production and commercial marketing (FAO, 2017; Sambo et al., 2023).
Sample Collection
Diseased Acha seeds exhibiting visible fungal contamination, including discoloration, shriveling, mold growth, or softening, were purposively sampled from six major locations across the state. Approximately 200–300 g of seeds per sample were collected and placed in sterile polythene bags, properly labeled, and transported to the laboratory under aseptic conditions to prevent further contamination (Pitt & Hocking, 2009).
Sample Preparation
Prior to isolation, seeds were manually cleaned to remove dirt and debris. From each sample, 50 seeds were randomly selected and surface-sterilized in 1% sodium hypochlorite solution for 1 minute, followed by triple rinsing with sterile distilled water to remove residual sterilant. Surface sterilization is critical for eliminating superficial contaminants while preserving seed-borne fungi (Barnett & Hunter, 1998).
Fungal Isolation Techniques
Two standard isolation methods were employed to recover fungi from the Acha seeds:
1. Blotter Method
Ten surface-sterilized seeds were placed on sterile, moist blotter paper in Petri dishes, which were incubated at 25 ± 2°C for 7 days. Emerging fungal growths were observed under a stereomicroscope, and cultures were sub-cultured to obtain pure isolates (ISTA, 2013; Leslie & Summerell, 2006).
2. Potato Dextrose Agar (PDA) Culture Method
Surface-sterilized seeds were plated on freshly prepared PDA and incubated at 28 ± 2°C for 5–7 days. Distinct colonies based on morphology were repeatedly sub-cultured to achieve pure fungal cultures (Samson et al., 2019). This dual approach enhances the recovery of both fast- and slow-growing fungi and provides complementary data on fungal diversity (Pitt & Hocking, 2009).
Morphological Identification
Pure fungal isolates were characterized based on colony morphology, color, growth rate, and texture on PDA plates. Microscopic examination of spores and hyphal structures was performed using lactophenol cotton blue staining. Identification was guided by standard taxonomic keys for seed-borne fungi (Barnett & Hunter, 1998; Samson et al., 2019).
Data Analysis
Fungal incidence and frequency were calculated as percentages of infected seeds per sample. Data were summarized using descriptive statistics and presented in tables to illustrate the distribution and prevalence of different fungal species across locations.
Table 1 shows the incidence of fungal infection in Acha seeds collected from six locations in Sokoto State. The overall fungal incidence across all locations was 61.7 ± 5.7%, indicating that a significant proportion of seeds were infected. Gwadabawa recorded the highest fungal incidence at 70.0%, followed by Kebbe (66.0%) and Sokoto South (64.0%). The lowest incidence was observed in Dange-Shuni (54.0%), with Wamakko (56.0%) and Bodinga (60.0%) showing moderate infection levels. These findings suggest that fungal contamination is widespread among Acha seeds in the study area, although some locations exhibited slightly higher susceptibility than others (Table 1).
Table 1: Incidence of Fungal Infection in Acha Seeds across Six Locations in Sokoto State
Notes: Seed sample size per location: 50 seeds (standard for seed-borne pathogen assessment; ISTA, 2013). Fungal incidence (%) = (Number of infected seeds ÷ Number of seeds examined) × 100.
Table 2 presents the frequency of fungal genera isolated from the diseased Acha seeds. Aspergillus spp. was the most frequently isolated genus, occurring in 60.5% of infected seeds. This was followed by Fusarium spp. at 42.2%, and Penicillium spp. at 24.3%. Rhizopus spp. and Curvularia spp. were less frequent, with occurrences of 18.9% and 15.1%, respectively. The total frequency exceeds 100% because some seeds were simultaneously infected by multiple fungal genera. Overall, the results indicate that Aspergillus and Fusarium are the dominant seed-borne fungi affecting Acha in the sampled locations (Table 2).
Table 2: Frequency of Fungal Pathogens Isolated from Diseased Acha Seeds
Table 3 shows the distribution of fungal genera across the six locations. Aspergillus spp. was consistently the most prevalent fungus across all locations, with the highest occurrence in Gwadabawa (72%) and the lowest in Dange-Shuni (55%). Fusarium spp. was also widely distributed, peaking in Gwadabawa (48%) and lowest in Dange-Shuni (36%). Penicillium spp. was moderately distributed, with higher prevalence in Kebbe (30%) and lower in Dange-Shuni (18%). Rhizopus spp. and Curvularia spp. were the least frequent, with mean incidences of 18.0% and 14.3%, respectively. This distribution indicates that fungal populations vary by location, with Aspergillus and Fusarium dominating in most areas, while other fungi are more sporadic (Table 3).
Table 3: Distribution of Fungal Genera Across Locations
The present study investigated the incidence, frequency, and distribution of fungal pathogens associated with diseased Acha (Digitaria spp.) seeds collected from Sokoto State, Nigeria. The overall fungal incidence recorded across the six locations was 61.7%, indicating a high prevalence of seed-borne fungi in the sampled areas. This finding aligns with previous studies that have documented the susceptibility of traditional cereals to fungal contamination under tropical and semi-arid conditions (Agrios, 2005; Pitt & Hocking, 2009). The variation in fungal incidence between locations, with Gwadabawa exhibiting the highest incidence (70%) and Dange-Shuni the lowest (54%), may be attributed to differences in local environmental conditions, storage practices, and handling of seeds prior to sampling, as previously suggested for cereals in West Africa (Bankole & Adebanjo, 2020).
The frequency analysis revealed that Aspergillus spp. was the most prevalent fungal genus, followed by Fusarium, Penicillium, Rhizopus, and Curvularia spp. The dominance of Aspergillus spp. is consistent with observations in other cereal grains, where this genus is commonly implicated in postharvest spoilage and mycotoxin contamination (Pitt & Hocking, 2009; Al-Sadi, 2023). The presence of Fusarium spp. in 42.2% of seeds is of particular concern due to its potential to produce fumonisins and other mycotoxins, which have documented health risks for consumers (Bankole & Adebanjo, 2020). The lower frequencies of Penicillium, Rhizopus, and Curvularia spp. suggest that while these fungi contribute to seed deterioration, they are less dominant in Acha seeds within the sampled locations (Table 2).
The distribution of fungal genera across the six locations indicated that Aspergillus and Fusarium spp. were consistently prevalent across all sites, suggesting that these pathogens are ubiquitous in the Acha production and marketing systems in Sokoto State. Similar patterns have been observed in studies on fonio and other cereals in West Africa, highlighting that environmental factors and storage conditions strongly influence fungal proliferation (Thiam & Teverow, 2020; Hwabejire et al., 2024). The sporadic occurrence of Penicillium, Rhizopus, and Curvularia spp. may be linked to localized micro-environmental factors, such as seed moisture content, handling practices, and exposure to ambient fungal spores (Agrios, 2005).
The predominance of seed-borne fungi in Acha seeds has important implications for food security and public health. Acha is highly valued for its nutritional properties and drought resilience, making it a critical staple in Northern Nigeria (Adoukonou-Sagbadja et al., 2006; Malomo & Abiose, 2020). However, fungal contamination can compromise seed viability, reduce grain quality, and lead to mycotoxin production, posing potential health risks to consumers (Bankole & Adebanjo, 2020; Rodríguez-Vargas et al., 2024). The findings of this study underscore the need for effective postharvest management strategies, including proper drying, hygienic storage, and regular monitoring for seed-borne fungi (Pitt & Hocking, 2009; Al-Sadi, 2023).
Morphological identification, as applied in this study, provided a reliable preliminary assessment of fungal diversity; however, future studies incorporating molecular techniques such as ITS sequencing would enhance taxonomic resolution and species-level identification (Nilsson et al., 2008; Nilsson, 2023). Accurate identification is critical, given the variability in mycotoxin production among closely related fungal species, and it can guide targeted interventions for reducing contamination in stored Acha grains.
Overall, the study demonstrates that fungal pathogens, particularly Aspergillus and Fusarium, are prevalent in Acha seeds from Sokoto State and pose challenges to seed quality, safety, and storage. Implementing integrated seed management practices and exploring potential biological or chemical control measures could mitigate these risks and ensure the sustainability of Acha production in the region (Hwabejire et al., 2024; Malomo et al., 2024).
This study revealed that Acha (Digitaria spp.) seeds from Sokoto State are widely contaminated by seed-borne fungi, with an overall incidence of 61.7%. Aspergillus spp. and Fusarium spp. were identified as the predominant fungal pathogens, occurring consistently across all sampled locations, while Penicillium, Rhizopus, and Curvularia spp. were less frequent. The presence of these fungi poses significant risks to seed viability, grain quality, and food safety, given their potential to produce mycotoxins. To minimise fungal contamination and preserve seed quality, it is recommended that Acha seeds be properly dried and stored under hygienic, moisture-controlled conditions immediately after harvest.
TETFUND funded this research under the Institution-Based Research (IBR) Annual Intervention; we therefore acknowledged their immense support. Also appreciates the Shehu Shagari College of Education, Sokoto.
Akinola, O., Olasoji, J., & Yusuf, A. (2018). Nutritional composition and utilization of fonio (Digitaria exilis) in West Africa. Journal of Food Science and Technology, 55(4), 1234–1241.
Amadou, I., Issa, K., & Abdoulaye, T. (2017). Agronomic and environmental adaptability of fonio (Digitaria exilis): Opportunities for sustainable food security. African Journal of Agricultural Research, 12(18), 1500–1509.
Bandyopadhyay, R., Leslie, J. F., & Visconti, A. (2007). Mycotoxins in cereals: Occurrence, prevention, and management. Annual Review of Phytopathology, 45, 95–118.
Barnett, H. L., & Hunter, B. B. (1998). Illustrated genera of imperfect fungi (4th ed.). APS Press.
Diouf, D. (2003). Fonio (Digitaria exilis Stapf & Digitaria iburua Stapf): An indigenous African cereal. Agricultural Systems, 76(1), 859–872.
Food and Agriculture Organization (FAO). (2017). Seed and plant health in Africa. FAO.
Hell, K., Cardwell, K. F., Setamou, M., & Poehling, H. M. (2000). The influence of storage practices on aflatoxin contamination in maize in West Africa. Journal of Stored Products Research, 36(4), 365–382.
International Seed Testing Association (ISTA). (2013). International rules for seed testing. ISTA.
Leslie, J. F., & Summerell, B. A. (2006). The Fusarium laboratory manual. Blackwell Publishing.
Ogunsola, F., Adeoye, T., & Olaniran, A. (2019). Fungal pathogens associated with stored cereal grains in Nigeria. Mycopathologia, 184(3), 421–430.
Pitt, J. I., & Hocking, A. D. (2009). Fungi and food spoilage (3rd ed.). Springer.
Samson, R. A., Houbraken, J., Thrane, U., Frisvad, J. C., & Andersen, B. (2019). Food and indoor fungi (2nd ed.). CRC Press.
Sambo, S., Muhammad, B. I., & Aliyu, I. H. (2023). Isolation and evaluation of seed-borne fungal pathogens of traditional cereals in Northern Nigeria. African Journal of Biotechnology, 22(7), 145–156.
Sharma, R., Kumari, P., & Singh, D. (2019). Seed-borne fungi and mycotoxin contamination in cereals: Implications for food safety. Journal of Plant Pathology, 101(2), 271–282.
Armiya’u, MA; Aminu, F; and Abdullahi. AA (2026). Isolation and Morphological Identification of Fungal Pathogens Associated with Diseased Acha (Digitaria spp.) Seeds in Selected Locations of Sokoto State, Nigeria. Greener Journal of Agricultural Sciences, 16(2): 89-93, https://doi.org/10.15580/gjas.2026.2.061326087.
Download [427.48 KB]
