Nitrite Accumulation Within Herbicide-Treated Leaves

Six herbicides including DNP (2,4-dinitrophenol) were tested for their effects upon nitrate metabolism in green leaves. It was found that these herbicides which are not classified as “photosynthetic inhibitors” permitted nitrite to accumulate within green leaves in darkness but not in light. It is postulated that these herbicides have an uncoupling effect, similar to that of DNP, which indirectly affects the process of nitrate reduction. A new technique which demonstrates this effect is presented and discussed.