Effect of Potassium Ferricyanide on Sunflowers (Helianthus annuus L. cv. HySun521)

摘要

Phytoremediation is a very effective method to remove explosives, nutrients, organic solvents or other unwanted chemicals from soil and groundwater. Potassium Ferricyanide K_3Fe (CN)_6, used in color photography, is somewhat toxic for plants at concentrations above 50 mg/L. Experiments were done with K_3Fe(CN)_6 and sunflowers (Helianthus annuus L. cv. HySun521). The seeds were germinated in vermiculite for ～6 days under fluorescent lights. The seedlings were then transferred to treatment solutions and grown hydroponically. A low nitrogen Hoagland's solution without iron and with added CaCl_2 (in place of Ca (NO_3)_2) was used. The purpose of this experiment is to make the plant survive only from the little Fe provided by K_3Fe (CN)_6. What we found is that with small volumes (150 ml) of 0, 50, 100, 150 and 200 mg/L K_3Fe (CN)_6, the plants do fairly well. There is a formation of a Prussian blue precipitate on the roots at higher concentrations (150 and 200 mg/L). However when we used larger volumes like 450 mL or 600 mL, the control with no added iron had pale leaves and the treated plants barely survived the first week. They started to recover during the second week. We realized that for the high volume even 25 mg/L was initially toxic for the sunflower plants. The most convincing explanation for recovery is an increase of ferric chelate reductase. The quantity of cyanide also appears to be an important factor.