Mycorrhizal Fungal Screening and Inoculant Effectiveness for Two Acacia Species

Preliminary results showed that the seedlings of Acacia mangium and A. crassicarpa were capable of forming ectomycorrhizal (ECM) and vesicular arbuscular mycorrhizal (VAM) associations. The average infective rates of both mycorrhizal associations varied from 49.5% to 73.33%. Five months after inoculation,the average heights of A.mangium and A.crassicarpa were increased by 53.9%～148.99% and 31.7%～95.39% respectively compared to those of controls. The biomass was accordingly increased by 208%～396% and 294%～441.5% respectively.Seedilings of both tree species indicated strong mycorrhizal dependency (MD) on inoculant fungi,except relatively weak MD for A.mangium on either VAM fungus isolate B9302 or ECM fungus 99215 and 94070.The highest MD were 542 of A. crassicarpa on ECM isolate 9439. Another experiment with various inoculum products showed that American inoculum No.2 posed the best effectiveness on the growth of seedlings. Among these fungal isolates,more compatible isolates for the two Acacia species were screened and can be further tested in field trials. Experimental results also indicated that inoculation with mycorrhizal fungi could enhance nodule formation by rhizobia.