GENETIC AND ENVIRONMENTAL VARIATION OF GUM CONTENT IN BARLEY

The influence of genetic vs environmental factors on the gum content of the barley grain has been studied by growing 4 varieties of barley, at 4 locations in the South of Spain, with 6 sowing dates at each location. The genetic factors proved to be the more important, accounting for 89% of the variation over locations and 71·5% of the variation among locations and sowing dates. Of the environmental factors studied, the sowing date was the most important. The variety × sowing date interaction was also statistically significant. Furthermore, the later the sowing date the higher the gum content of the grain. There was no variety × location interaction and, therefore, the varieties ranked in the same order at each location. It was also demonstrated that there was a different pattern of response for the varieties when grown in environments which were able to induce high or low gum content, suggesting that low gum content‐low response varieties should be grown if the grain is to be used as an adjunct in brewing.