Effects of endomychorrhizal inoculation on the growth and survival of Jatropha curcas L., Acacia mangium Willd. and Casuarina equisetifolia (L.) J.R. and G. Forst. seedlings in nickel-mined soil in Southern Palawan, Philippines

The influence of vesicular-arbuscular-mycorrhiza fungi (VAMF) on the growth of Jatropha curcas, Acacia mangium and Casuarina equisotifolia in the abandoned mined soil with 1.01% nickel concentration was examined at the experimental area of WPU [Western Palawan Univ.], Aborlan, Palawan for 8 months. To evaluate the growth performance, the height, diameter, biomass yield, root volume, root-shoot ratio, and NPK uptake were used as parameters. Nickel content of plant tissues was used to determine phytoremediation potential of the species. In the nickel mined soil, A. mangium (70.19 cms) obtained significantly better height performance than C. equisetifolia (56.12 cms) and J. curcas (24.67 cms). Acacia mangium showed no significant difference on biomass yield in the nickel mined sites (22.63 g/plant) and fertile soil (29.21 g/plant); and root volume at 14.20 cu cm and 16.79 cu cm, respectively. The non significant variations on biomass yield and root volume on both soils indicate that this species had performed even in the nickel contaminated soil. VAM-inoculated seedlings height of C. equisetifolia was significantly higher with a mean of 2.14 cm compared to the uninoculated seedlings with 0.52 cm. The same species also registered larger stem diameter by 260% over the non-inoculated seedlings. On P uptake, VAM inoculated seedlings significantly improved J. curcas by 39.06% in the fertile and 33.33% in the nickel-mined soil while no significant variations observed for A. mangium and C. equisetifolia. On the other hand, VAM influence was evident on the nickel uptake of A. mangium which accumulated statistically higher amount of nickel at 12.22 mg/kg as against the 7.26 mg/kg from the uninoculated seedlings. Based on the results, C. equisetifolia and A. mangium showed potential candidate species for the rehabilitation of the abandoned mined soil in Palawan.