Before progress can be made in the selection of barley varieties (or genotypes) which have superior straw quality it is necessary to demonstrate stability for indicators of straw quality. This means that the ranking of genotypes from those with superior straw value down to those with lower value should be broadly similar when planted either at the same location in different years (or growing seasons) or in the same growing season at different locations. A preliminary test which can be carried out is to compare variation in straw quality caused by genotype with genotype x season interaction variation following removal of variation caused by blocks and season.

Barley straw was obtained from 20 genotypes grown, in randomised blocks with three replications, in successive seasons in Syria where rainfall was 229 mm in 1983/84 and 373 mm in 1984/85. There were two experiments, one where the plots had been grazed by sheep at the tillering stage and another where plots were left ungrazed. The material planted consisted of 62-rowed and 146-rowed genotypes.