Temporal dynamics of wild herbaceous arbuscular mycorrhizal fungi under crop succession: Rice-bean-amaranth-okra-eggplant

Arbuscular mycorrhizal fungi (AMF) are ubiquitous symbionts that colonize approximately 80% of wild and cultivated plants, with the exception of a few botanical families such as Amarantaceae, Brassicaceae, Cyperaceae, and Chenopodiaceae, which mycorrhizae less or not at all. These symbioses are important because they improve the hydro-mineral nutrition of plants. During a succession of crops on a plot, it is possible to observe the diversity of AMF in the soil; this work fits into this framework. The experiment was carried out in pots in a completely randomized block design with 5 crops, including rice-beans-amaranth-okra-eggplant, repeated 5 times. The temporal dynamics of AMF were assessed during crop succession on the same soil. The results show a high species richness for rice, with 23 AMF species compared to 9 AMF species found on amaranth. Spore density and root colonization frequency show the same trend, respectively 5 to 38 spores per 100 g soil for rice compared to 3 to 10 spores per 100 g soil for amaranth. The colonization frequency ranged from 79 to 80% in rice and bean, while amaranth was only colonized to 13%. The introduction of amaranth during crop succession contributes to a decrease in species richness, spore density and AMF colonization frequency, in contrast to other crops.