banner 45. Effect of increasing nitrogen fertilization on barley protein content and endosperm modification during malting

A. L. MACLEOD (1), M. S. Izydorczyk (1), J. T. O’Donovan (2); (1) Canadian Grain Commission, Winnipeg, MB, Canada; (2) Agriculture and AgriFood Canada, Lacombe, AB, Canada

Poster Presentation

Only about 25% of barley is selected for malting in Western Canada annually due to strict quality specifications, including acceptable levels of grain protein. While application of nitrogen fertilization can increase yield, it can also impair quality by increasing protein to undesirable levels. Barley with high grain protein content is difficult to modify and limits the amount of potential extract. The objective of this study was to determine the responses of four relatively new malting barley cultivars (AAC Synergy, CDC Kindersley, Voyageur, and Cerveza) to increasing nitrogen rates compared to the response of AC Metcalfe, the most commonly grown malting cultivar in Western Canada. In the first year of this study, the five cultivars were grown at four rates of nitrogen fertilization (0, 25, 50, and 100 kg/ha), producing grain with a range of protein levels. While increasing rates of nitrogen fertilization generally resulted in increased grain protein levels and associated decreases in malt extract, not all varieties responded similarly. AAC Synergy and CDC Kindersley had lower levels of protein at higher nitrogen levels. This resulted in better endosperm modification as indicated by improved friability, lower wort β-glucan, and increased levels of soluble protein. Preliminary results suggest that varieties differ with respect to their ability to resist the negative effects of increasing rates of nitrogen, resulting in smaller reductions in friability and malt extract than the check cultivar, AC Metcalfe. This indicates that the need to restrict application of nitrogen fertilizer in order to achieve acceptable grain protein levels, which has a detrimental effect on yield, can be overcome with specific variety choices.

Aaron MacLeod joined the Canadian Grain Commission in 2005 and is currently a chemist in the Barley Research Unit of the Grain Research Laboratory. The unit provides quality assurance for malting barley grown in Western Canada and conducts research on factors affecting malting barley quality and quality measurement methods. Aaron holds a B.S. degree in chemistry from the University of Western Ontario. He has been a member of ASBC since 2008, has participated in collaborative studies of numerous methods, and is currently a member of the ASBC Technical Committee.

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