Seasonal Effects on Arbuscular Mycorrhizal Fungi Diversity and Colonization in Cowpea (Vigna unguiculata L. Walp) Rhizosphere of Rainforest Soils

This study investigated the impact of seasonal variation on the richness and composition of Arbuscular mycorrhiza fungi (AMF) communities in soil from rainforest vegetation in Rivers State, Nigeria. Samples of top soil (0-15cm) and subsoil (15-30cm) were collected from rainforest vegetation in Port-Harcourt, and sampling months were categorized into rainy season, peak of rainy season, dry season and peak of dry season based on the data obtained from NiMET during the study period. A potted experiment was carried out at the teaching and research farm of the Rivers State University from January to April (dry season) and April to July (rainy season) to determine the colonization status of AMF in rhizosphere soils planted with cowpea. Morphology and microscopy were used for AMF identification. A total of eight genera of AMF namely: Glomus, Acaulospora, Gigaspora, Paraglomus, Rhizophagus, Dentiscutata, Archeaospora, and Clariodeglomus were isolated and identified in rhizosphere soils of cowpea cultivated, and the mycorrhiza genera followed the order: Acaulospora > Glomus > Archeaspora > Clariodeoglomus > Rhizophagus > Paraglomus > Dentiscutata > Gigaspora. AMF colonization and population was higher in the dry season than in the rainy season indicating that seasonal variations has an impact on AMF diversity, population, and colonization of cowpea rhizosphere. Seasons can be taken advantage of to improve plant productivity and health.