Efficient propagation of arbuscular mycorrhizal fungal propagules

Abstract:

[Background] Arbuscular mycorrhizal (AM) fungi can form mutualistic symbiosis with most plants to promote the growth and enhance the stress resistance of plants, playing an important role in production. However, the immature propagation technology limits the application of AM fungi. [Objective] To establish an efficient propagation system of AM fungi. [Methods] A pot experiment was conducted. Specifically, Rhizophagus intraradice was inoculated into four propagation systems constructed with three host plants (Sorghum bicolor, Zea mays, and Trifolium repens) and five substrates (zeolite, river sand, peat, perlite, and vermiculite) for culture. The effects of different propagation systems on the infection and sporulation of R. intraradice were studied. Then, we measured the infection ability of AM fungi by inoculating S. bicolor with propagation inoculum to verify the propagation effect. Finally, the optimal propagation conditions were employed to explore the propagation of other species of AM fungi: Funneliformis mosseae, Clariodeoglous etunicatum, Diversispora versiformis, and Acaulospora delicate. [Results] The propagation system with river sand+vermiculite+peat (1:4:1) as the substrate and Z. mays+T. repens, R. intraradice as the host plants had the highest spore production of 1 912 spores/g-dry substrate. Moreover, the AM fungi propagated with this system showed better infection potential and remarkably increased the aboveground biomass of S. bicolor. In addition, the propagation with this system increased the sporulation of F. mosseae, C. etunicatum, D. versiformis, and A. delicate by 6.24, 2.92, 35.18, and 4.18 times, respectively, compared with that before propagation. [Conclusion] The propagation system with Z. mays+T. repens as the host plants and river sand+vermiculite+peat (1:4:1) as the substrate had the optimum results. This system had the aeration porosity of 3.57%, the water-holding porosity of 48.19%, the bulk density of 1.03 g/cm³, the electrical conductivity of 152.5 μS/cm, pH 5.61, the available phosphorus of 5.6 mg/kg, the available nitrogen of 80 mg/kg, the available potassium of 449.8 mg/kg, and the organic matter of 56.11 g/kg, which are conducive to the efficient propagation R. intraradice and other AM fungi.

Key words:arbuscular mycorrhizal fungi;substrate;host plant;spore density