Dependency, colonization, and growth in Gmelina arborea inoculated with five strains of Arbuscular Mycorrhizal Fungi

Gmelina arborea is a forest species of increasing use in the establishment of commercial plantations in Colombia. The areas where it is currently planted are deficient in nutrients, so the use of Arbuscular Mycorrhizal Fungi (AMF) can be an alternative to improve phosphoric fertilization. The aim of this work was to determine the mycorrhizal dependency, colonization, and growth of G. arborea when it is inoculated with Rhizoglomus fasciculatum, Rhizoglomus aggregatum, Rhizoglomus irregulare, Glomus fistulosum, and Entrophospora colombiana, under different concentrations of phosphorus (P) in a soil solution. A completely randomized design was used with a 6×3 factorial arrangement, five AFM strains + control (uninoculated) and three P doses (0.002, 0.02, and 0.2 mg L-1) with five replicates per each treatment and twice through time. Mycorrhizal colonization and dependency, foliar concentration of P, dry biomass, leaf area, and height were evaluated. A moderate mycorrhizal dependency was obtained under a P concentration of 0.002 and 0.02 mg L-1 and inoculation with R. fasciculatum, R. aggregatum, and R. irregulare while inoculation with G. fistulosum and E. colombiana produced a marginal dependency. It was found a negative effect on G. arborea inoculated with all AMF strains under 0.2 mg L-1 of P. Mycorrhizal colonization presented values between 62.5 - 2.5% for all the AMF evaluated, influenced by AFM strains and P concentration. Plants inoculated with R. fasciculatum, R. aggregatum, and R. irregulare showed a significant increase (P<0.05) in their growth. Mycorrhizal dependency and colonization in G. arborea and its growth were highly influenced by species of AMF and amount of P.