A Tabular Summary of Research Dealing with Translocation of Foliar-Applied Herbicides and Selected Growth Regulators

Abstract

HE table briefly summarizes research findings involving the 1 translocation of organic herbicides and certain selected growth regulators in higher plants. Gibberellic acid, indoleacetic acid, naphthaleneacetic acid and other non-herbicide growth regulators are for the most part not listed except when used in experiments with the more generally accepted herbicides. For tabular information on translocation of auxins and other growth substances, the reader is referred to the Handbook of Biological Data, mentioned later. Information in the table is based on techniques which primarily utilize foliar application and for the most part does not include application via root system, injection, or bark application. As a consequence, most substances listed may be assumed to be transported predominantly in the phloem, but in numerous cases the compounds also move into the xylem. Many organic substances applied to a plant are broken down to different metabolic products within the plant. However, an increasing number of recent studies (made possible largely by radiochromatography) indicate that a significant portion of most organic materials may be translocated within the plant in the same molecular form in which it was applied. Consequently, for simplification of tabulation, the materials listed in the Substance column are considered to be those applied to the plant. As to the column, acropetal (A) or basipetal (B) may be defined as movement in a morphologically upward or downward directon, respectively. It should be stressed, however, that the direction shown is specific only for the experiment described and may vary according to growth stage, concentration of substance applied, technique of application, etc. Translocation rate, if given under Remarks, was either specified by the investigator or calculated from data presented. Such rates do not necessarily represent maximum or even mean values for the conditions of the experiment; in many instances they were simply based upon the time (after treatment) at which harvest or assay of specific plant parts happened to take place. In most experiments, the time factor upon which rate is based includes time of absorption from cuticular surface to phloem. Although certain techniques eliminate the absorption factor, true translocation rate within the phloem may well be greater than the figures given in many cases. Wherever several plants and herbicides are listed under a single entry it does not necessarily follow that all herbicides were tested