Studies on the rate of root growth of intact seedlings in a herbicide medium

Abstract

Resume: ZusammenfassungTime-lapse cine photography was used to measure at 10-min intervals over 72 h the growth rate of pea and barley roots during separate exposure of the shoot + seed, root or entire seedling to eight herbicides. Times for commencement of root inhibition were determined at exposure to concentrations causing 50 % inhibition in 72 h.Root growth rate was normal in both species during shoot + seed treatment. Root inhibition commenced at the same time in a given species, when only the root or the entire seedling were treated with a particular herbicide. Except for dinoseb, times for commencement of root inhibition differed between pea and barley and between each herbicide. In pea these times ranged from t2 5 h with diuron to 23-7 h with diphenamid, and in barley from tl-1 h with diphenamid to 21-3 h with EPTC. Root growth ceased in only a few cases during the experimental period.EPTC, diphenamid, dinoseb, and trifluralin (on barley only) effectively inhibited root elongation, whereas diuron, simazine, paraquat, dalapon, and trifluralin (on pea only) had no direct effect on root growth at normal field rates of application. Etudes sur le taux de croissance des racines de plantules intactes dans un milieu herbicideLe cin6ma avec prise de vue image par image, k des intervalles de 10 minutes, a 6t6 utilis6 pour mesurer, pendant 72 heures, le taux de croissance des racines de pois et d'orge, soumises k l'action de huit herbicides, en traitant s6par6ment soit l'ensemble pousse + semence, soit la racine, soit la plantule entifere. On a d6termin6 les dur6es d'apparition de l'inhibition des racines, en utilisant des concentrations provoquant 50% d'inhibition en 72 heures.Le taux de croissance des racines fut normal chez les deux especes pendant le traitement pousse + semence. L'inhibition des racines commenfa au mSme moment chez une espfece donn6e lorsque les racines seules ou la plante entiere furent trait6es avec un herbicide particulier. Les dur6es d'apparition * Present address:

Uptake and phytotoxicity of chlorsulfuron in Zea mays L. in the presence of 1,8‐naphthalic anhydride

“…When the shoot zone was treated with chlorsulfuron, approximately 50% inhibition of both shoots and roots occurred (Table 1). This result at this young stage of seedling growth differed from that of Parker (1966) who, using the same technique, found that treating the shoot of sorghum with EPTC, diallate, CDEC and dichlobenil had no effect on root growth over 84 h. Similarly, O'Sullivan & Prendeville (1974) found little herbicide movement and no effect on root growth, when shoots of barley and pea were treated with EPTC, dinoseb and trifluralin over 72 h. They suggested that since the food reserves of cotyledons are transported to the rapidly developing shoot and root meristem, any herbicides absorbed by the young shoot are probably translocated acropetally, therefore would not be expected to affect root growth immediately. If absorbed by shoots these herbicides are probably not transported basipetally to roots over 72 h. Chlorsulfuron on the other hand, as indicated by root inhibition, displayed marked basipetal transport over 96 h (Table 1).…”