PHYTOTOXICITY OF SOIL-APPLIED DICHLORFOP METHYL AND ITS EFFECT ON UPTAKE OF 45Ca IN WILD OATS, BARLEY AND WHEAT

Abstract

The effect of placement of dichlorfop methyl 2[4-(2,4-dichlorphenoxy)-phenoxy propionic acid methyl ester] in the soil at the shoot and root zones of wild oats (Avena fatua L.), barley (Hordeum vulgare L. ''Conquest'') and wheat (Triticum vulgare L. ''Thatcher'') on plant growth and uptake of 45Ca was investigated. Dichlorfop methyl was more toxic to the roots and aerial plant growth via root exposure than shoot exposure. Wild oats was most sensitive, followed by barley and wheat. Severe root inhibition caused by dichlorfop methyl was associated with decreased uptake of 45Ca from the root zone. Root-applied dichlorfop methyl enhanced adventitious root development in the shoots of wild oats and barley, resulting in a 50 and a 127% increase in shoot uptake of 45Ca, respectively. Shoot-applied dichlorfop methyl strongly inhibited adventitious root formation with a resultant decrease in 45Ca uptake of 100 and 86%, respectively, from the shoot zone. In wheat, neither adventitious roots nor uptake of 45Ca from the shoot zone occurred.