Effects of Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Fungus on the Rooting, Growth and Rhizosphere Niche of Beach Plum (Prunus maritima) Cuttings in a Phosphorus-deficient Soil

The effects of an arbuscular mycorrhizal fungus (AMF), Funneliformis mosseae, and a phosphate-solubilizing fungus (PSF), Apophysomyces spartima, and their interactions, on rooting, cutting biomass, phosphorus (P) concentrations, rhizosphere microorganisms, phosphate concentrations, phosphatase activities and pH of beach plum (Prunus maritima) hardwood cuttings in a low phosphorus soil were evaluated. AMF colonization was also assessed. AMF, PSF, or both inoculations strongly promoted rooting, P concentrations, root and shoot dry weight (DW), numbers of bacteria and actinomycetes on the rhizoplane and in roots, numbers of nitrogen-fixing bacteria on the rhizoplane, available phosphate concentrations, and acid phosphatase enzyme activities in the rhizosphere soil of beach plum cuttings. Dual inoculation with AMF and PSF also resulted in significantly higher root colonization, rooting percentage, number of lateral fine roots, DW of roots and shoots, number of bacteria and actinomycetes on the rhizoplane and in roots, number of nitrogen-fixing bacteria on the rhizoplane, available phosphate concentrations, acid phosphatase activities, and the lowest pH values than following a single inoculation with AMF or PSF. Compared to FM + AS autoclaved treatment, AMF, PSF, or both inoculations had no influence on numbers of bacteria and actinomycetes in the rhizosphere, nitrogen-fixing bacteria in the rhizosphere and roots, fungi in the rhizosphere, roots and on the rhizoplane of beach plum cuttings. These results showed that AMF inoculation, plus the application of PSF, synergistically improved soil microenvironment and increased P availability in the rhizosphere of beach plum, which improved the rooting and growth of beach plum cuttings in a low phosphorus soil.