evaluation of wheat and barley cultivars tolerance to metribuzine application

in order to study of barely and wheat cultivars tolerance to metribuzin, a factorial experiment was conducted as a completely randomized design, with three replications in greenhouse of agricultural research at ferdowsi university of mashhad. treatments included wheat cultivars (backcross roshan, cross arvand, bahar, sepahan, gascosion, sayonez, bam garmsiry, garmsiri, ghods, pishtaz, chamran and shoori 6), barely cultivars (macouyi, karoon and bahman) and metribuzin application rates ( 0, 175, 350, 700, 1050, 1400 and 2100 gr. ai.ha-1). metribuzine was applied at 3-4 leaf stage and 3 weeks after herbicide spraying, plants survival and their biomass were determined. results showed that metribuzin application had a significant effect (p≤0.01) on barley and wheat dry weight. based on results, mertibuzin application did not affect on barley cultivars up to 30 g.a.i.ha-1 but in wheat varieties lead to significant reduction in their biomass and survival. increasing of metribuzin rates reduced wheat and barley cultivars biomass (p≤0.01). barely varieties were less sensitive than wheat cultivars to metribuzine. the highest and the lowest ed50 in wheat cultivars were observed in cross arvand (940) and shoori (25) varieties, respectively. in barley cultivars the highest and lowest ed50 were observed in macouyi (614) and karoon (396), respectively.