Aging and Substrate Type Effects on Iodide and Iodate Accumulation by Barley (Hordeum vulgare L.)

Abstract

The mechanism of iodine uptake by plants from soil is the interest of many studies, though the information about the uptake mechanism and iodine mobility in soil is still insufficient. The uptake of the most common naturally occurring iodine species in soil—iodide and iodate by barley (Hordeum vulgare L.) from iodine-spiked soil and agar cultivation media was evaluated in our study based on laboratory pot and petri dish experiments. Soil pot experiments were conducted in two stages: after iodine spiking and after a 3-month aging period taking account on the processes that can influence iodine bioavailability. Our results indicate that iodine bioavailability does depend on the form of iodine present in the growth substrate, the character of the substrate itself, and the time between iodine application and plant cultivation. The loss of iodine from soil via volatilization can also be a limiting factor to iodine bioavailability. Our results provide additional information on iodine mobility and behavior in soil and suggest plants’ essential role in biogeochemical cycle of iodine. We also highlighted importance of iodine source and speciation on the base level of the food chain where iodine mobility and bioavailability is limited by its chemical form, substrate characteristics, and intensity of natural biogeochemical processes related to iodine biotransformation.