Differential Reaction of Lolium perenne Genotypes to Certain Herbicides

Abstract

THE rapid progress in weed destruction made possible simply by introducing new chemicals has resulted in a concentration on obvious and gross effects. Examples of the selective toxicity of various chemicals between different plant genera and between different species of the same genus¹ have been widely reported. Much less frequently cited are differential responses between varieties of one species. In potatoes, variation in varietal reaction to pre-planting application of trichloroacetic acid (TCA) has been noted² and large differences in varietal susceptibility to 2 : 4-dichlorophenoxyacetic acid (2,4D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA)³ have been found. Hayes⁴ has demonstrated the differential response of barley to DDT, susceptible varieties being killed by DDT application. Commercial varieties of sugar-cane differ in physiological tolerance to dalapon⁵. Fiddian⁶ gave evidence of differential susceptibility of cereal varieties to some commonly used herbicides, variation occurring in amount of leaf scorch, growth deformity, ripening retardation, ear malformation and spikelet sterility.