Harnessing indigenous mycorrhizal symbiosis to boost sorghum productivity and phosphorus-use efficiency on contrasting Sudanese vertisols

Sorghum productivity on vertisols is constrained by phosphate fixation, salinity, and nutrient limitations, undermining food security in semi-arid regions. We evaluated the impact of indigenous arbuscular mycorrhizal fungi (AMF) inoculation on growth, yield, and phosphorus (P) dynamics of four Sudanese sorghum cultivars across two vertisol sites: Abassyia (salinity - sodicity stress) and Medani (P deficiency). Field inoculation with indigenous AMF consortia (Rhizophagus, Glomus, Claroideoglomus, Funneliformis, Entrophospora, Scutellospora, and Acaulospora) improved sorghum performance, increasing biomass, panicle length, grain yield, root colonization, spore density, and phosphorus acquisition efficiency (PAE). Inoculated plants achieved colonization levels of 52-81% and spore densities up to 4894 spores per 100 g soil, with PAE increasing to 132 mg P plant- 1. Shoot P concentration and plant height were unaffected; no conclusion can be drawn regarding P allocation. Cultivar- and site-specific responses identified Tabat as the most productive cultivar (36.6 g grain yield plant- 1), while Tetron showed superior PAE. Multivariate analyses confirmed strong associations between AMF colonization, biomass, and yield, with clustering of inoculated and uninoculated plants. These findings provide robust field evidence that leveraging indigenous AMF biodiversity enhances P-use efficiency and sorghum productivity on vertisols, supporting sustainable biofertilization in low-input systems in sub-Saharan Africa under climate-stressed environments.