<em>FRANKIA</em> STRAINS FOR IMPROVING GROWTH, BIOMASS AND NITROGEN FIXATION IN <em>CASUARINA</em> <em>EQUISETIFOLIA</em> SEEDLINGS

Abstract

Casuarina equisetifolia fixes atmospheric nitrogen (N) to produce root nodules where actinomycete fixes atmospheric N for all metabolic activities of plant. Two strains of Frankia (CeFr1, CeFr2) were isolated, cultured in artificial propionic acid medium and analysed for nitrogenase activity by acetylene reduction assay to ascertain their capabilities in N fixation. Seedlings of C. equisetifolia were inoculated with Frankia strains in the nursery and their growth performances were assessed. Seedlings inoculated with Frankia strains showed improved growth, biomass and tissue N content over control seedlings. Nitrogenase activity of Frankia strains were significantly (p < 0.05) and negatively correlated with tissue N content. Inoculated seedlings were then planted on a farmland without adding fertilisers and assessed after 2 years. Seedlings inoculated with CeFr1 and CeFr2 showed significantly improved growth in height (9.5 and 8.4 m respectively) compared with control. Seedlings inoculated with Frankia strains achieved > 95% survival and had improved biomass and N fixation.