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  • Effect of soil management on rhizosphere microbial structure and function in olive grove
    Publication . Kacem, Ibtihel; Baptista, Paula; Campos, Carolina Ribeiro
    Microorganisms are an important component of the rhizosphere, having a direct impact on soil health and crop yield. However, the factors that drive their assembly are not fully understood. Such knowledge will offer the opportunity to manipulate these microorganisms, in such a way, to increase beneficial plant-microbe interactions. Here was evaluated the effect of different soil managements on rhizospheric microorganisms of olive tree. Accordingly, within an olive orchard were collected rhizospheric soil samples from tilled and not-tilled soils and from soils with spontaneous cover vegetation or sowing, and used to analyse both bacterial and fungal community by using a culture dependent PCR-based identification approach. Overall, the bacterial community was dominated by the phylum Proteobacteria and genus Pseudomonas, while fungal community was dominated by Ascomycota and genus Penicillium. Tillage practices exhibited contrasting effects on fungal and bacterial communities, exerting a stronger influence on fungal community. Indeed, tillage showed to reduce significantly the fungal diversity and abundance, while bacterial richness was unaffected by tillage. Still, distinct fungal and bacterial community’s composition was detected among tilled vs. not tilled soils, mainly due to the exclusive presence of Mortierellaceae and Janthinobacterium in tilled soils, and Pseudogymnoascus, Solicoccozyma and Rhodococcus in not tilled soils. The cover crop had no impact on both fungal and bacterial community ́s diversity and structure. Still, a number of fungal and bacterial taxa were exclusively found either on seeded or not seeded soils. The capacity of phosphate solubilization and synthesis of indole acetic acid (IAA) of the isolates obtained was evaluated in vitro. Out of the 64 strains tested, all produced IAA and 47 were able to solubilize phosphate. The isolates showing the highest plant-growth-promoting proprieties, are potential inoculants for olive tree soils. However, the need remains to reveal the long-term effects of tillage practices and cover crop on rhizospheric bacteria and fungi composition and functionality.
    2023Dissertação de mestrado Acesso aberto Ver mais