EFFECT OF ARBUSCULAR MYCORRHIZAL FUNGI ON GROWTH OF VETIVER GRASS (CHRYSOPOGON ZIZANIOIDES L.) AND ITS ARSENIC UPTAKE FROM SOIL AND WATER SYSTEMS

Arsenical pesticides were widely used in agriculture for a long period of time, thus increasing the background soil concentration of arsenic in farmed lands. Increasing urban population and the resulting sprawl has led to the development of suburban residential properties on former agricultural lands in many metropolitan areas in the US and abroad. The risk of human exposure to arsenic, which is a group I human carcinogen has thus become a major point of concern. Plant-based technology is a sustainable method for environmental protection in residential areas because of both economics and aesthetics. Plant cover prevents direct contact of children with backyard soils, and lowers the amount of house-dust resulting from soil erosion. Earlier greenhouse studies in our lab showed that vetiver grass (Chrysopogon zizanioides) is capable of growing in arsenic enriched soils; and take up low to moderate amounts of arsenic, indicating potential use as a landcover species. In this study, we investigated if arbuscular mycorrhizal fungi (AMF) could improve arsenic tolerance and uptake in vetiver grass, using both hydroponic and soil systems. For the hydroponic study, vetiver grass was grown in solutions containing 0, 150, 300 and 500 micromoles of arsenic for four weeks. For the soil column study, vetiver was grown in arsenic-spiked soils (0, 12.5, 25 and 50 mg/kg) in a greenhouse for four weeks. Plants were grown in the presence or absence of AMF. An ameliorative effect of the AMF infection in enhancing plants growth was found. In addition, AMF-inoculated plants accumulated more arsenic from both contaminated systems than those non-inoculated, although the differences were not always statistically significant (p < 0.05). Plants grown hydroponically translocated higher amounts of arsenic from roots to the aboveground parts. Longer term studies are needed to better understand the impact of AMF on arsenic tolerance and uptake by vetiver grass.