Abstract

MARTINS, Marco A.  and  CRUZ, Andre F.. The Role of the external mycelial network of arbuscular mycorrhizal fungi: III. a study of nitrogen transfer between plants interconnected by a common mycelium . Rev. Microbiol. [online]. 1998, vol.29, n.4, pp. 289-294. ISSN 0001-3714.  http://dx.doi.org/10.1590/S0001-37141998000400011.

An experiment under greenhouse conditions was carried out to evaluate the relative contribuition of arbuscular mycorrhizal fungi (AMF) in the process of nitrogen transfer from cowpea to maize plants, using the isotope ¹⁵N. Special pots divided in three sections (A, B and C), were constructed and a nylon mesh screen of two diameters: 40µm (which allowed the AMF hyphae to pass but not the plant roots) or 1µm (which acted as a barrier to AM hyphae and plant roots) was inserted between the sections B and C. Section A had 25.5 mg of N/kg using (¹⁵NH₄)2SO₄ as N source. Two cowpea seedlings inoculated with Rhizobium sp. were transplanted with their root systems divided between the sections A and B. Ten days later, 2 seeds of maize were sown into the section C which was inoculated with Glomus etunicatum. Thirty-five days after transplanting, the maize plants were harvested. AMF inoculation increased dry weight and ¹⁵N and P content of maize plant shoots. Direct transfer of ¹⁵N via AMF hyphae was 21.2%; indirect transfer of ¹⁵N mediated by AMF mycelium network, was 9.6%, and indirect transfer not mediated by AM mycelium network , was 69.2%.

Keywords : mycorrhizae; cowpea; maize; nitrogen transfer.