Accumulation of copper and phosphorus by mycorrhizal and non-mycorrhizal food crops

This study aimed to determine the accumulation of copper (Cu) and phosphorus (P) by food crops growing in mine waste soil. Soil and plant samples from Krus and Rocky Mountain mining sites in Paracale, Camarines Norte [Philippines] were collected and examined for indigenous vesicular mycorrhizal fungi (VAM) and heavy metal content in different plant parts. In a screenhouse experiments, food crops such as eggplant, tomato, malunggay and gabi were either uninoculated or inoculated with commercial mycorrhizal inoculant MYKOVAM, indigenous mine VAM fungi coded as Paracale isolates, Glomus etunicatum or Gigaspora margarita and planted in mine waste soil from Paracale, following a Randomized Complete Block Design with ten replicates. Results show that 11 week-old tomato seedlings inoculated with Paracale isolates and MYCOVAM inoculated malunggay seedlings obtained the highest shoot, root and total dry weight. Paracale isolates promoted highest root, shoot, bulb and total biomass of gabi. MYCOVAM inoculated malunggay accumulated the greatest P concentration in the leaves and P uptake in the roots. In gabi, G. margarita stimulated the highest P concentration in the leaves and P uptake in the bulb. Cu concentration and Cu uptake were greatest in the bulb of uninoculated gabi. By contrast, Cu uptake by MYCOVAM inoculated gabi was concentrated in the roots indicating the potential of MYCOVAM in preventing the transport of heavy metals from the roots to the bulb and to the leaves. Results suggest that, mycorrhizal inoculation should be done on food crops planted in mine waste soil to increase plant growth, plant biomass and nutrient uptake but reduce the heavy metal accumulation by food crops. The food crops tested in this study were prematurely harvested because of the small pot size. It is highly recommended that further studies should be conducted to verify the high heavy metal accumulation in the edible portions of food crops collected in mine sites.