The response of Cochliobolus sativus to ultraviolet-C radiation

Isolates of Cochliobolus sativus, the cause of common root rot of barley, w ere collected from different regions of Syria, and exposed in the laborator y to ultraviolet-C (UV-C) light (254 nm) during periods of 40 or 60 h with a dose rate of 2.52 x 10(-3) W/cm(2). Significant increases (P < 0.001) in mycelial growth and sporulation were detected in comparison with the nonirr adiated 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, respec tively. Some of the isolates retained and some increased in virulence. Thes e data demonstrate that variation occurred in the virulence level and the r esistance level of isolates and among accessions, respectively.