Screening for resistance to leaf rust (Puccinia hordei) in a collection of Spanish barleys

A collection of 418 Spanish barley accessions was screened for resistance to leaf rust in the field at Cordoba, Spain during the 2002-2003 season. Six accessions displaying the lowest disease severity with no macroscopically visible necrosis were selected for further studies on components of resistance. Five of them showed a significantly higher relative latency period than the susceptible line L94 and were similar to the partially resistant Vada. All of them showed lower relative infection frequency and smaller colony size than the susceptible L94 under controlled conditions. Histological studies indicated that the resistance in four of these accessions was based on a higher percentage of early aborted colonies not associated with host cell necrosis. In the remaining two accessions, resistance was based on hypersensitivity.