Etiolated Growth of Range Grasses for an Indication of Tolerance to Atrazine

Abstract

Our purpose was to investigate the influence of growth reserves of perennial range grasses on their tolerance to applications of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Competing annual grasses were removed with atrazine treatment at 1.1 kg/ha. The carbohydrate reserves of the perennial grasses were reduced by mowing the previous season. Crested wheatgrass [Agropyron desertorum(Fisch. ex Link) Schult.] plants with reduced carbohydrate reserves, as indicated by reduced etiolated growth, were less tolerant to atrazine than their nonmowed counterparts. Without reduced carbohydrate reserves, squirreltail [Sitanion hystrix(Nutt.) J. G. Smith] was much more susceptible to atrazine than crested wheatgrass. Thus, the weed control treatment did not necessarily increase the density of desirable perennial grasses.