A population of 103 recombinant inbred lines (RILs) of barley, that were developed from the cross L94x’Vada’ was evaluated at seedling stage for resistance against scald (Rhynchosporium secalis) in a sporeproof air-conditioned glasshouse. Two isolates of R. secalis were used: B9 and 13-13. Both isolates were collected in fields at SCRI (Scottish Crop Research Institute) near Dundee, Scotland, UK. Under glasshouse conditions, two quantitative trait loci (QTLs) for partial resistance (PR) to scald were identified.

One QTL (Rrsq1) was detected on chromosome 3 (3H) for latency period and lesion length only against B9 isolate, whereas the other QTL (Rrsq2, on chromosome 7H) was identified for lesion length of both isolates. Rrsq1 was mapped at a region where a QTL was detected, using the same population, for partial resistance to scald under field conditions whereas Rrsq2 was mapped at a similar position as the locus Rrs2 for scald resistance. These cases of co-location of QTL with major genes, not very common, may suggest that some QTL are actually alleles of known major resistance genes.