Effects of Inoculating Symbiotic Microorganisms on Acacia mangium Grown on Coconut Fiber

The ability of Acacia mangium to grow on degraded soils, thanks to its ability to fix atmospheric nitrogen, makes it a very important species in agroforestry and in the restoration of impoverished soils. However, all the experiments on Acacia mangium, whether inoculated or not, have only been carried out on a single type of substrate, i.e. soil. The aim was to determine whether inoculation significantly increased the biomass and height growth of Acacia mangium grown on coconut fiber. The experimental design comprised 5 treatments (Ta, T, M, R, and MR) with 5 replicates. Characterizing the coconut fiber and the dry biomass of Acacia mangium above ground and roots consisted of determining the content of elements such as P, K, Ca, Mg, and N. The number of nodules was also counted The results showed that inoculation (M, R and, MR) had no significant effect on the height growth and biomass of Acacia mangium. Non-inoculated (Ta and T) plants showed greater growth, probably due to the richness of nutrients (N, P) in the coconut fiber. The presence of nodules in the non-inoculated plants indicates the presence of indigenous strains in the coconut fiber. Double inoculation (mycorrhizae/rhizobia) significantly stimulated the growth and nodulation of Acacia mangium. Double inoculation also increased substrate fertility, which had a positive effect on plant growth. The Glomus-Bradyrhizobium combination appeared to be the most effective in improving the growth and nodulation of Acacia mangium.