Seasonal and soil influences on arbuscular mycorrhizal fungal root colonization in three different subtropical orchard trees

Arbuscular mycorrhizal fungi (AMF) form a mutualistic relationship with plant roots, which is crucial for plant adaptation, growth, and nutrient uptake, especially under drought and nutrient-deficient soil conditions. However, the strength of this interaction can vary depending on climatic, edaphic, and host-plant species factors. It is essential to explore the factors that govern the AMF association with plant roots to maximize crop and soil productivity in subtropical climatic condition. The current study aims to identify the key factors that influence the interaction between the host-plant and AMF throughout the year. The study was conducted in three orchards namely Mangifera indica L., Psidium guajava L., and Citrus aurantiifolia C. during the winter, summer, and rainy seasons from December, 2024 to August, 2025 in subtropical soils of southwest Bangladesh. The results showed that hyphal and vesicle colonization were the highest in the rainy season, followed by winter, and the lowest in summer across all the host-plant species (P < 0.05). In contrast, arbuscule colonization was observed predominantly during the winter season. Hyphal, vesicle, and arbuscule colonization were the highest in M. indica, followed by P. guajava , and the lowest in C. aurantiifolia (P < 0.05). Correlation analysis revealed significant negative associations between mycorrhizal colonization and soil available phosphorus, sulfur, pH, and electrical conductivity (P < 0.05). Principal Component Analysis (PCA) indicated that colonization patterns were seasonal and plant-specific. These findings suggest that the extent of AMF colonization is influenced by a combination of climatic conditions, edaphic factors, and host-plant species, rather than by any single factor.