Effects of Endomycorrhizal Inoculation on the Growth of Jalropha curcas L., Acacia mangium Willd., and Casuarina equisetifolia J. R. & G. Forst Seedlings in Nickel-Mined Soil in Southern Palawan, Philippines

The influence of vesicular-arbuscular-mycorrhizal fungi (VAMF) on the growth and survival of Jatrophu curcas, Acacia mangium and Casuarina equisctifolia in the abandoned mined areas with 1.01% nickel concentration (161 times greater than the normal nickel concentration for natural soils) was examined at the experimental area of the Western Philippines University (WPU), Aborlan, Palawan for 8 months. The study aimed to determine rehabilitation strategies in the abandoned mined sites in the province. Specifically, the objectives of the study were to: (1) Evaluate the growth performance of J. curcas, A. mc.mgiurn and C. equisetijblia seedlings in the fertile and nickel-contaminated soils with VAM ink.-)culation; (2) Determine the phytoremediation potential of three species in the nickel-mined soil. The height, diameter, biomass yield, root volume, root-shoot ratio, were used as parameters to determine the growth and nutrient pattern uptake of the species. Nickel content of plant tissues was used to determine phytoremediation potential of the species. In the nickel mined soils. Acacia mungium (70.19 cms.) obtained significantly better height performance than Casuarina equisetijalia (56.12 cms.) and Jatropha curcas (24.67 ems.). The Acacia mangium also showed no significant difference on biomass yield in the nickel mined soil (22.63g/plant) and fertile soil (29.21g/plant); and root volume at 14.20 cms.3 and 16.79 ems.' respectively. The non-significant variations on biomass yield and root volume on both soils indicate that Acacia Maligium had performed even in the nickel contaminated soil. VAMF-inoculated seedlings of Casuarina equisetifolia were significantly taller with a mean of 2.14 crns. as compared to the non-inoculated seedlings with 0.52 cm. Casuarina equisetifolia also registered larger stem diameter by 260% over the non-inoculated seedlings. VAMF influence was evident on the nickel uptake of Acacia mangium which accumulated statistically higher amount of nickel content at 12.22 mg/kg. of its dry weight as against the 7.26 mg/kg from the non-inoculated seedlings. Based on the results, the growth and survival of Acacia nangiu,n and Casuarina equiseulalia in the nickel contaminated soil manifest tolerance to nickel toxicity and therefore potential as rehabilitation species in the abandoned nickel mined sites in Palawan.