The Intra‐cellular Localization of the Herbicide Diphenamid in Corn Root .Tip

Abstract

The intra‐cellalar localization of the herbicide N,N‐dimethyl–2,2‐diphenylacetamide (diphenamid) was examined in 10 mm root tips of corn seedlings (Zea mays L. cv. Shawnee). Experiments are described which culminate in the observation that a significant, measurable effect on root growth occurs within 12 hours after treatment with diphenamid. Corn seedlings were then treated with 14‐C‐diphenamid for 12 hours and the 10 mm root tips excised and homogenized. By use of differential centrifugation and gel filtration, the root homogenate was separated into fractions; as follows; cell wall, mitochondria, microsomal, protein and eluate. The highest concentration of the herbicide was found in the root tips. Furthermore, most of the radioactivity was found in the eluate. Results are discussed as to localization of diphenamid in the microsomal and protein fraction and possible mode of action.

Environmental Influences on the Selectivity of Diphenamid in Seeded Tomato (Lycopersicon esculentum)

“…capitata L.) plants, diphena mid decreased the uptake of macronutrients, further indicat ing root effects (11). Deli and Warren (2) theorized that di phenamid is a reversible metabolic inhibitor which stops or slows mitosis in susceptible plants; however, Yaklich and Scott (16) stated that inhibition of mitosis does not occur, and theo rized that growth reduction is due to a reduction in the ex pansion of cell walls. Due to the differences in rate of move ment of diphenamid out of the roots between tolerant and susceptible plants, Bingham and Shaver (1) postulated that the selectivity may be due to differential rates of translocation from roots to shoots.…”