Potential of Plant Growth Regulators to Enhance Arsenic Phytostabilization by Pennisetum purpureum cv. Mott

The limited translocation of arsenic from contaminated soil to plant biomass is one way to decrease human exposure to arsenic (As). Plant growth regulators (PGR), including salicylic acid, indole butyric acid, and calcium, have been reported to alleviate toxicity and decrease the accumulation of heavy metals in many plants. Thus, this study has investigated the effect of plant growth regulators, including salicylic acid, salicylic acid + calcium chloride, indole butyric acid, and indole butyric acid + calcium chloride, to stimulate the growth and phytostabilization of Pennisetum purpureum cv. Mott grew in arsenic-spiked soil. The results showed shoot growth, root growth, and total chlorophyll content of P. purpureum cv. Mott grown in non-spiked soil were not significantly different from those grown in arsenic-spiked soil. Only the root-to-shoot ratio of plants grown under arsenic-spiked soil (0.28) was higher than that of non-spiked soil (0.19). Exogenous plant growth regulator application of each formula did not stimulate the growth of plants grown under both soil conditions. The most suitable plant growth regulator was indole butyric acid + calcium chloride, as the highest arsenic accumulation in plant roots was detected (47.38 mg/kg). It corresponds with the arsenic bioaccumulation factor, translocation factor, and efficiency, which were 4.52, 0.06, and 9.77% when using exogenously indole butyric acid + calcium chloride. Meanwhile, arsenic’s translocation factor and efficiency were low when using the other formulae of plant growth regulators. Thus, 0.001 mM indole butyric acid + 20 mM calcium chloride may be used for the cultivation of P. purpureum cv. Mott as a forage crop in areas with low levels of arsenic contamination because it could limit the amount of arsenic entering the food chain.