Inhibition of the ferricyanide‐Hill reaction of isolated bean leaf chloroplasts by 3,5‐diiodo‐4‐hydroxybenzonitrile (ioxynil) and related compounds

SUMMARY The effect of ioxynil and several related compounds on the photoreduction of ferri‐cyanide by isolated bean leaf chloroplasts has been studied. In general, a close correlation was found between the herbicidal activity of these compounds and their capacity to inhibit the photoreduction; ioxynil was highly active. The established weedkiller dinitro‐ ortho ‐cresol (DNC) which is a less potent contact herbicide than ioxynil, was also much less effective as an inhibitor for this reaction.