Field Nodulation in Nine Species of Casuarina in Victoria

Abstract

Field nodulation was examined in Victoria in nine species of Casuarina: C. cristata Miq.; C, littoralis Salisb.; C. luehmannii R. T. Baker; C. monilifera L. A. S. Johnson; C. muelleriana Miq.; C. paludosa Sieber ex Spreng.; C,paradoxa E. D. Macklin; C.pusilla E. D. Macklin; C. verticillata Lam. Of 336 plants examined at 77 sites, nodules were found on 46 plants (15%) at 13 sites (17%) and on only three species (C. littoralis, C. paludosa and C. verticillata). No nodules were found at sites more than 70 km from the coast but nodules were not found at all coastal sites. Nodulation in glasshouse experiments, in which seeds from each site were grown in the corresponding habitat soil, confirmed field nodulation findings in 68 (88%) of sites; exceptions were three sites of C.paludosa, three sites of C.paradoxa, one site of C.pusilla and two sites of C. verticillata (within 200 km of the coast), in which glasshouse but not field nodulation was detected. The identity of the nodules was confirmed microscopically by morphological similarity to known structure of actinorhizal nodules. This is the first systematic survey of field nodulation in Victoria and the first record of nodulation in C. paludosa and C. paradoxa.