The Response of Cochliobolus sativus to Ultraviolet-C Radiation

Isolates of Cochliobolus sativus, the cause of common root rot of barley, were collected from di€erent regions of Syria, and exposed in the laboratory to ultraviolet-C (UV-C) light (254 nm) during periods of 40 or 60 h with a dose rate of 2.52 ´ 10±3 W/cm2. Signi®cant increases (P < 0.001) in mycelial growth and sporula- tion were detected in comparison with the non- irradiated control, and these increased with increasing exposure to UV-C. This exposure increased the mycelial growth by 89 and 100% in the isolates CR9 and CR19, respectively, and the number of spores by 10- and 13-fold, respectively. Some of the isolates retained and some increased in virulence. These data demonstrate that variation occurred in the virulence level and the resistance level of isolates and among accessions, respectively.