Ethnobotanical and Ecological Bases for Preference and Availability of Black Nightshade in Southwest Nigeria

Abstract

Aim: This study evaluated users’ preferences and ethnobotanical knowledge and examined the associations of floristic, climatic, and edaphic factors with the distribution and availability of Solanum nigrum L. Study Design: A cross-sectional mixed-methods observational study involving ethnobotanical surveys, floristic assessments, soil analysis, and evaluation of climatic factors. Place and Duration of Study: Oyo, Osun, and Ondo States, Southwest Nigeria, from September 2024 to January 2025. Methodology: A multistage sampling technique was applied: three Local Government Areas (LGAs) per state, one town per LGA, and one sampling site per town. A semi-structured questionnaire administered to 41 respondents captured demographic and socio-economic information related to knowledge and preference. Floristic distribution was assessed using 45 quadrats (0.25 m², five per location). Topsoil (0–15 cm) samples from 27 points were analysed for physical and chemical properties, while meteorological data were obtained via Google Earth Engine. Data were analysed using univariate and multivariate statistics, including diversity indices and canonical correspondence analysis (CCA). Results: The results showed that 48.8% of respondents recognised S. nigrum L., whereas only 2.4% cultivated it; reported constraints included lack of awareness (24.4%) and farmland loss (61%). Only 39% of respondents preferred the plant for food or medicinal use. Floristic surveys identified S. nigrum L. as a dominant species at some locations, where it co-occurred with several other herbaceous species. Soil analysis indicated an association with phosphorus-rich, well-drained sandy soils. CCA indicated that the distribution of S. nigrum L. was associated with precipitation, humidity, temperature, and solar radiation. Conclusion: Low cultivation and utilisation of S. nigrum L. in Southwest Nigeria were associated primarily with limited awareness and declining farmland availability. The observed climatic conditions and soil characteristics were compatible with its occurrence, suggesting scope for improved cultivation, conservation, and utilisation through greater awareness and promotion.