In this study, commercially produced malts were used for small-scale simulated mashing trials to investigate the impact of differences in the level and thermostability of malt diastatic power (DP) enzymes on the resultant wort fermentability. A modified European Brewery Convention/American Society Brewing Chemists mashing protocol was used with mash-in temperatures ranging between 45 and 76°C for full-malt and 30% rice adjunct mashes. Malt extract yield varied little with mashing temperature for most varieties in this temperature range. However, the fermentability, maltose content, and free amino nitrogen of that extract was considerably affected by mashing temperature with 65°C achieving the highest fermentability for all malt varieties. Multilinear regression analysis of full-malt and rice adjunct mashing trials at 65°C using 43 commercial malts showed that the level of α-amylase and total limit dextrinase activity, Kolbach Index, and the total β-amylase activity level and thermostability were the most important malt quality predictors of wort fermentability. These conclusions suggest that the conventional DP assessment could be replaced with the measurement of its component enzymes outlined above so that maltsters could better satisfy brewers malt quality expectations by blending and defining their malt quality in terms of these fermentability predicting factors. This information would be particularly useful to brewers who brew with multiple varieties and blends from different suppliers. The focus on individual enzyme characteristics by barley breeders is likely to provide selection targets that are more accurate and achievable.

Cultivar differences in root elongation under B toxic conditions were observed in barley (Hordeum vulgare L.). A significant increase in the length and width of the root meristematic zone (RMZ) was observed in Sahara 3771 (B tolerant) when it was grown under excessive B concentration, compared to when grown at adequate B supply. This coincided with an increase in cell width and cell numbers in the meristematic zone (MZ), whereas a significant decrease in the length and no significant effect on the width of the MZ was observed in Clipper (B intolerant) when it was grown under excessive B supply. This was accompanied by a decrease in cell numbers, but an increase in the length and width of individual cells present along the MZ. Excessive B concentrations led to a significantly lower osmotic potential within the cell sap of the root tip in SloopVic (B tolerant) and Sahara 3771, while the opposite was observed in Clipper. Enhanced sugar levels in the root tips of SloopVic were observed between 48 and 96 h after excess B was applied. This coincided with an increase in the root elongation rate and with a 2.7‐fold increase in sucrose level within mature leaf tissue. A significant decrease in reducing sugar levels was observed in the root tips of Clipper under excessive B concentrations. This coincided with significantly lower root elongation rates and lower sucrose levels in leaf tissues. Results indicate a B tolerance mechanism associated with a complex control of sucrose levels between leaf and root tip that assist in maintaining root growth under B toxicity.