Phytorestoration using Arbuscular Mycorrhizal Fungi in Association with Desert Plants in Boron-Contaminated Soils

Borax mining at the Rio Tinto boron mine in Boron, California has caused pollution of soil, desertification of local habitats, and loss of biodiversity due to severe boron contamination. I conducted a phytoremediation study to test the effects arbuscular mycorrhizal fungi in association with native plant species. The goal of this study was to evaluate the effect of arbuscular mycorrhizal fungi on desert plants’ ability to tolerate the boron pollution from Rio Tinto soils. I evaluated bush peppergrass (Lepidium fremontii), quail bush (Atriplex lentiformis), desert dandelion (Malacothrix glabrata), white cheesebush (Hymenoclea salsola), and cattle spinach (Atriplex polycarpa) in Rio Tinto soils containing three different levels of boron. Eight replicates of each species grew in each soil type, with half inoculated with arbuscular mycorrhizal fungi. After four weeks of growth in the Rio Tinto soils, I harvested, cleaned, and dried the plants. I measured fresh weights immediately after harvesting and dry weights after forty-eight hours of oven drying to determine biomass accumulation. The results of the study indicate that in general arbuscular mycorrhizal fungi acts as a parasite on plants in order to obtain nutrients rather than a symbiont under high boron conditions, leading to significantly lower survival and biomass accumulation in plants inoculated with arbuscular mycorrhizal fungi compared to those that were not inoculated. The results indicate that the addition of arbuscular mycorrhizal fungi to native plants is not a viable addition for increasing plant survival or biomass accumulation for phytoremediation purposes at the Rio Tinto boron mine.