Mycorrhizae, phosphorus and nitrogen supply on initial growth of "trema" and "fedegoso"

The response of "trema" (Trema micrantha (L) Blum.) and "fedegoso" (Senna macranthera Rich.), both native woody species, to phosphorus (P), nitrogen (N) and inoculation with arbuscular mycorrhizal fungus (AMF) was studied in pots using a low-fertility clayey Dark Red-Latosol (Oxisol) Sample. The study, composed of two experiments, was carried out under greenhouse conditions at the Soil Science Department of Universidade Federal de Lavras, state of Minas Gerais, Brazil, from march 1993 to april 1994. Both species grew poorly in the absence of added P and exhibited great response to this fertilizer. Inoculation with Glomus etunicatum Becker & Gerd. (Ge) resulted in beneficial plant growth effects in both species. Inoculated plants reached 80% of the maximum growth when 100 mg kg-1 of P in the soil was added to trema and of 80 mg kg-1 of P in the soil to fedegoso. Trema and fedegoso plants non-inoculated with Ge, but colonized by indigenous fungi, required 3.2 and 1.5 times, respectively, more P to reach 80% of maximum growth. Addition of mineral N alone did not promote plant growth of any species. The addition of soluble phosphate and the presence of AMF propagules are of great importance for initial growth of the studied species in low-fertility soils.

native woody species; forestation; arbuscular mycorrhiza; soil fungi; Glomus etunicatum

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