The reaction of three spring barley varieties exposed to epidemics of Rhynchosporium secalis of varying intensity and duration

Abstract

SummaryThree spring barley varieties, Proctor, Vada and Mosanne, were inoculated with Rhynchosporium secalis(Oudem.) J. J. Davies at Growth Stages 3, 7, 10·1 and 10·5 (Large, 1954). The treatments included single inoculation at each growth stage and multiple inoculations at two, three and four of the above growth stages. There was no effect of inoculation oil the number of fertile tillers. Thousand-grain weight was reduced in all seven inoculation treatments in Mosanne but only the quadruple inoculation adversely affected the other two varieties. Numbers of grains of both Mosanne and Vada were reduced by treatments which included an inoculation at ear emergence but Proctor was affected only by the quadruple inoculation. In terms of disease assessment Mosanne was very susceptible and Proctor moderately resistant but Vada, with symptom scores only slightly better than Mosanne, exhibited a degree of tolerance which was reflected by the grain weight results in which small increases were recorded. This tolerance mechanism, possibly acting through compensation in this variety, is compared with compensation reported in wheat.