Comparative Analysis of Lavandula Dentata Rhizosphere Microbiota Across Different Developmental Stages in a Semi‐Arid Area

Abstract

The positive effects of soil microbiota on plant growth and stress tolerance are well established. However, their role in aromatic and medicinal plants, particularly under arid conditions, remains underexplored. This study examined rhizospheric microbial community dynamics across developmental stages of wild Lavandula dentata L., a semi-arid species threatened with extinction in Morocco. Results showed total microbial biomass peaked at senescence, mainly due to increases in Gram-negative (25.02 μg/g) and Gram-positive (18.11 μg/g) bacterial biomasses. Beta diversity analysis revealed consistent dominance of Actinobacteria, with peaks during senescence and the vegetative phase. Saprotrophic fungi (8.81 μg/g) and arbuscular mycorrhizal fungi (AMF) (4.16 μg/g) biomasses peaked at flowering. The fungal community was dominated by the Ascomycota phylum, with no significant variation across stages. The AMF genus Glomus remained most abundant throughout development. Senescence featured the most complex interkingdom interaction network and high ecological niche heterogeneity, reflected by more negative associations. Overall, the rhizospheric microbial community of L. dentata shifts with plant development, with flowering and senescence as key phases for microbial biomass accumulation and community diversification. Flowering and senescienceez stages seem to represent promising targets for developing biostimulant consortia to improve soil health and crop productivity in arid environments.