Effects of 3,5–diiodo‐4–hydroxybenzonitrile (ioxynil) on barley root growth and uptake of phosphate from culture solutions

SUMMARY Low concentrations (c. 10‐6 m) of 3,5–diiodo‐4–hydroxybenzonitrile (ioxynil) supplied to barley seedlings in culture solution promote a marked increase in root length and uptake of phosphate is also increased by this treatment. When [125I]ioxynil was supplied to barley seedlings through the roots for 7 days, the presence of 3,5–diiodo‐4–hydroxybenzoic acid (DIHB) was detected in the root tissue.