Beneficial Effect of Rhizospheric Soils of Some Native Mediterranean Plants on Germination and Early Growth of Almond (Prunus dulcis (Mill.))

Abstract

Native soils host diverse symbiotic microflora that contribute to sustainable agricultural practices and plant establishment. This study aims to investigate the benefits of rhizosphere soil microbiota associated with four Mediterranean native plants, Rhus pentaphylla (NS1), Drimia maritima (NS2), Pistacia lentiscus (NS3), and Withania frutescens (NS4), growing in proximity to the local Moroccan almond variety Prunus dulcis (Mill.) (NS5). Native soils were applied directly as living substrates to evaluate their effects on the germination and early development of almond, with particular emphasis on the potential of arbuscular mycorrhizal fungi (AMFs). Root analysis revealed high mycorrhizal colonization intensity (M% = 87.5–95%) and infectivity (F% = 100%). Under the tested soil conditions, three native soils (NS1, NS3, and NS5) achieved germination rates exceeding 70% after 28 days. Moreover, NS5 and NS1 soils showed the strongest effects on almond germination and seedling growth, respectively. Overall, the use of native soils enhanced almond germination and early development, highlighting the role of AMFs as natural biofertilizers. The associated native plant species may also function as nurse plants that facilitate almond establishment. These findings support the use of the rhizosphere microbiome as a bio-based strategy to promote sustainable almond cultivation in local and Mediterranean agroecosystems.