Fertilization and plant development stage as drivers of fungal community dynamics in the sorghum (Sorghum bicolor) rhizosphere

Fertilization influences crop productivity and soil microbial communities, yet its effects on fungal dynamics across plant developmental stages remain insufficiently resolved. This study examined the impact of organic (cow dung) and inorganic (NPK) fertilization on sorghum rhizosphere fungal communities across vegetative, reproductive transition, and maturity stages. High-throughput ITS sequencing generated 49,403–56,498 reads per sample, yielding 31,761–35,978 high-quality reads and 5487 ASVs after rarefaction (1118–1298 ASVs per sample). Alpha diversity showed clear treatment and stage effects, with NPK supporting higher richness at the vegetative stage (ACE ≈ 507), while cow dung promoted greater diversity and evenness at maturity (Shannon ≈ 4.20), compared with lower diversity in control soils (ACE ≈ 265; Shannon ≈ 3.54). Beta diversity analyses demonstrated significant but generally moderate differences in fungal community composition among fertilization treatments and developmental stages (ANOSIM R = 0.17–0.59, P < 0.05). Community differentiation decreased during the reproductive transition stage, resulting in partial convergence of fungal assemblages before divergence increased again at physiological maturity. Ascomycota dominated across all samples (60–80%), with NPK enriching Eurotiomycetes, Pleosporales, and Hypocreales, whereas cow dung favored Basidiomycota and saprotrophic genera such as Cladosporium, Fusarium, Cercophora, and Podospora. Functional prediction using FUNGuild indicated an increased relative abundance of saprotrophic and symbiotrophic fungal guilds under organic fertilization, whereas the unfertilized control and NPK-treated soils showed relatively higher abundances of pathotrophic guilds. Circos visualization revealed stage-dependent differences in the distribution and relative associations of dominant fungal taxa across fertilization treatments, with organic fertilization supporting a broader representation of dominant fungal taxa, particularly at physiological maturity. Overall, fertilization regime and plant developmental stage were significantly associated with fungal community assembly and succession, with observed patterns corresponding to differences in soil physicochemical properties.