Interaction between root growth allocation and mycorrhizal fungi in soil with patchy P distribution
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Interaction between root growth allocation and mycorrhizal fungi in soil with patchy P distribution Bernd Felderer & Jan Jansa & Rainer Schulin
Received: 1 May 2013 / Accepted: 13 June 2013 # Springer Science+Business Media Dordrecht 2013
Abstract Aims and Background Many plants preferentially grow roots into P-enriched soil patches, but little is known about how the presence of arbuscular mycorrhizal fungi (AMF) affects this response. Methods Lotus japonicus (L.) was grown in a low-P soil with (a) no additional P, (b) homogeneous P (28 mg pot−1), (c) low heterogeneous P (9.3 mg pot−1), and (d) high heterogeneous P (28 mg pot−1). Each P treatment was combined with one of three mycorrhiza treatments: no mycorrhizae, Glomus intraradices, indigenous AMF. Real-time PCR was used to assess the abundance of G. intraradices and the indigeneous AMF G. mosseae and G. claroideum. Results Mycorrhization and P fertilization strongly increased plant growth. Homogeneous P supply enhanced growth in both mycorrhizal treatments, while heterogeneous P fertilization increased biomass production only in treatments with indigenous AMF inoculation. Preferential root allocation into P-enriched soil was significant only in absence of AMF. The abundance of AMF species was similar in P-enriched and unfertilized soil patches. Responsible Editor: Erik J. Joner. B. Felderer (*) : R. Schulin Soil Protection Group, Institute of Terrestrial Ecosystems, ETH Zurich, Universitätstrasse 16, 8092 Zurich, Switzerland e-mail: [email protected] J. Jansa Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Praha, Czech Republic
Conclusion Mycorrhization may completely override preferential root growth responses of plants to Ppatchiness in soil. The advantage of this effect for the plants is to give roots more freedom to forage for other resources in demand for growth and to adapt to variable soil conditions. Keywords Preferential root growth . Arbuscular mycorrhizal fungi . Lotus japonicus . Heterogeneous . Phosphorus . Root allocation
Introduction Phosphorus (P) is an essential macronutrient element that is limiting plant growth in many natural and cultivated soils. Many soils are deficient in plant available P, because the availability of dissolved P is often limited by the low solubility of Ca, Fe and Al phosphates or strong binding to specific sorption sites (Hinsinger 2001). When roots take up P from the rhizophere solution, re-supply from the bulk soil is limited by solubilization of P from the solid matrix and transport of the dissolved P to the roots. Diffusion is the main transport process, and diffusivity of P is a critical factor that often co-limits the P uptake rate of roots in combination with the low solubility of solid P phases. The P nutrition of around 80 % of all plant species benefits from a mutualistic association with arbuscular mycorrhizal fungi (Smith and Read 2008). Arbuscular mycorrhizal fungi (AMF) overcome the problem of low P diffusivity by growing their hyphae
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