A rapid technique for determining common root rot reaction in barley

The reaction of two barley cultivars ('Thibaut' and 'Arizona') and three li nes (AECS 76, 'Tadmor' and WI 2291) to infection by Cochliobolus sativus wa s evaluated by three methods. Deep seeding of inoculated seeds was performe d in pots and field. Gibberellin (GA3) was applied to inoculated seeds in v itro. Susceptibility assessments were made in vitro at 2 weeks, and in pots at 7 weeks after inoculation, using a scale of 1 (very resistant) to 5 (ve ry susceptible) according to the percentage infected area of the subcrown i nternodes. There were no differences between the results using the three me thods. 'Arizona' was the most susceptible, whereas 'Thibaut' and AECS 76 we re partially resistant genotypes. The WI 2291 line and 'Tadmor' were modera tely susceptible and moderately resistant, respectively. In vitro tests yie lded the same order as tests from pot and field experiments.