Resistance of barley landraces and wild barley populations to powdery mildew in Jordan

Eleven barley (Hordeum vulgare L.) landraces and 12 wild barley (H. spontaneum) populations, collected from diverse eco-geographical regions of Jordan, were screened for resistance to powdery mildew. The average powdery mildew disease score (based on a 0 to 4 severity scale) was <1 in all tested barley landraces. Disease scores in wild barley populations ranged from 1.2 to 3.8. Most barley landraces of all tested lines were highly resistant to powdery mildew. The percentage of wild barley lines exhibiting high resistance was 19%, while 45% of the lines were moderately resistant and 36% susceptible to powdery mildew. There was no significant correlation between weather variables (precipitation, temperature and altitude) and the disease scores of either the barley landraces or the wild barley populations. However, resistance in wild barley was more common in humid districts and at higher altitudes. Both barley landrace and wild barley accessions could serve as potential donors for powdery mildew resistance genes to be transferred to barley varieties improved by plant breeding.