Field assessment of aeroponically grown and nodulated Acacia mangium

Acacia mangium seedlings were grown and nodulated with selected elite strai ns of Bradyrhizobium spp. under aeroponic conditions. The aeroponics system is well known for furnishing a very rich air environment around the roots and has been shown in our earlier work to induce rapid growth and enhance p erformance of Acacia seedlings under greenhouse conditions. This paper repo rts that the positive effects on growth, such as increased height and leaf area, induced by aeroponic culture with the Bradyrhizobium strains, Tel 2 f rom Malaysia and Aust 13c from Australia, continued to be sustained for 4 m onths after plants were transferred to field conditions. Random sampling an d analyses of Bradyrhizobia by polymerase chain reaction restriction fragme nt length polymorphism (PCR RFLP) also showed that Aust 13c continued to pe rsist in root nodules of inocualated plants in the field, with inoculated p lants having significantly higher nitrogen and phosphorus concentrations as well as higher photosynthetic rates than non-inoculated controls. The A. m angium plants were only 8 months old from germination but had already reach ed mean heights of approximately 2.4 m. The results suggest that aeroponic growth and nodulation should be further investigated for their potential to promote growth of A. mangium, especially on difficult soils.