STUDIES ON THE TRANSLOCATION IN AGROPYRON REPENS OF 14C‐LABELLED 2,2‐DICHLOROPROPIONIC ACID

Abstract

Summary. Previous findings suggested that the translocation in Agropyron repens of 2,2‐dichloropropionic acid (dalapon) may be considerably affected by the transpiration rate. This relationship has been studied further in the present investigation using 14C‐labelled material and autoradiography.It was found that when dalapon was applied to the leaves and the treated plants were placed in darkness a reduction in the transpiration rate of ca. 90% was associated with a marked increase in the amount of dalapon translocation into the roots and tillers. The evidence provided by the autoradiographs was confirmed by a quantitative assay of the 14C present in the roots. It was also found, however, that translocation was not appreciably affected either by a 50% reduction in the light intensity or when the transpiration rate was reduced by placing the plaints under conditions of high humidity in the light or by the application of white petroleum jelly to the leaves. An alternative hypothesis, namely that the effect of darkness on the movement of the herbicide might be due to changes induced in the normal pattern of assimilate translocation was also investigated but was not supported by the results obtained. Further experimentss, in which various parts of the treated shoot were placed in the dark, suggested that the effect of darkness on the translocation of dalapon is exerted primarily on the treated leaf itself. Etudes sur to migration dans Agropyron repens de l'acide 2,2‐dichloropropionique marqué avec 14C