Isolates of Stagonospora nodorum that varied in levels of aggressiveness were used in both controlled environment and field tests to determine whether isolate aggressiveness enhanced selection of resistant wheat genotypes. Two segregating wheat populations that differed in mean levels of resistance to S. nodorum were developed. Components of resistance measured in controlled environments indicated significant differences among isolate treatments. Measurement of disease severity in field studies also indicated significant differences among the isolate treatments. For the breeding population (random selections of genotypes in F 3 , F 4 , F 5 , and F 6 generations), incubation period measured in both juvenile and adult plant tests were most highly correlated with resistance measured in the field. For the biparental population (progeny of a resistant by susceptible cross), incubation period and percent leaf area diseased on the flag leaf for adult plant tests were most highly correlated with resistance measured in the field. Rankings of genotypes based on their resistance in both field and controlled environment tests indicated that five of the ten most resistant genotypes measured under controlled conditions were also identified as resistant in field tests. Similarly, four of the ten most susceptible genotypes measured under controlled conditions were also identified as susceptible in field tests. Combinations of adult and juvenile screening tests may allow for the identification of up to eight of ten genotypes resistant in controlled environments that are also resistant in field tests.

English

9910|AGRIS 0001

Jose Juan Caballero

CIMMYT Publications Collection