Soil physic-chemical properties, arbuscular mycorrhizal fungi (AMF) diversity and abundance in the rhizosphere of calotropis procera in two wild locations of semi-arid Eastern Kenya

Abstract

Soil and root samples were randomly collected from the rhizosphere of Calotropis procera (Calotropis) growing in two wild locations of Makueni and Tharaka-Nithi Counties, Kenya. The root samples were assessed for arbuscular mycorrhizal fungi (AMF) colonization. The soil samples were analyzed for physic-chemical properties and screened for the presence, abundance and diversity of AMF. The AMF inoculum potentials of the soils were determined using the bioassay test. The results depicted significant variations between the sites in soil pH, % sand, % clay, % silt, available P and Mg concentrations. These soil parameters had, generally, marked effects on AMF colonization, spore numbers and genus richness from the correlation analysis results. The Makueni site registered slightly higher mean spore densities than the Tharaka-Nithi site. Tharaka-Nithi site recorded relatively higher genus richness and AMF root colonization percentage than the Makuenisite. Overall, 6 AMF genera were identified in the soils, of which 4 (Dentiscutata, Scutellospora, Glomus and Acaulospora) were discovered in both sites while 2 (Gigaspora and Rhizaphagous) occurred in Tharaka-Nithi site only. Glomus was comparatively dominant and ubiquitous in both sites. The genera Dentiscutata, Scutellospora, Glomus and Acaulospora could possibly be tested for suitability as mycorrhizal inoculants of Calotropis seedlings in the dry lands of Kenya.