DIFFERENTIAL TOLERANCE OF TWO BARLEY CULTIVARS TO METRIBUZIN

Abstract

In greenhouse and growth cabinet studies, two cultivars of barley (Hordeum vulgare L. ’Klondike’ and ’Summit’) were found to differ in their tolerance to postemergence applications of metribuzin. Klondike was more susceptible than Summit, although both displayed varying amounts of injury depending on environmental conditions. Klondike was most susceptible following herbicide application at the three-leaf stage; when soil was moist at application; and when application was followed by a period of cold (0 °C). For both cultivars, high relative humidity and increasing duration of a dark period following spraying increased the injury from metribuzin. Increasing the duration of a light period following spraying had the opposite effect. The magnitude of the light/dark regime response was greater for Klondike than for Summit.Key words: Barley cultivar tolerance, metribuzin, environmental factors