Role of nitrogen and dry matter partitioning in determining the quality of malting barley

Abstract

Variation in quality of grain for malting is caused by a complex set of interacting factors during the growth of the crop. Poor quality grain resulting from high screening percentage, high nitrogen (N) concentrations, or low malt extract levels occur particularly when soil conditions are dry during grain filling or if soil N management is inappropriate for dryland conditions. Commercial and experimental malting barley crops (Hordeum vulgare L. ‘Triumph') were monitored over three seasons to determine if the variation in quality could be explained by differences in the pattern of partitioning of crop dry matter (DM) and N accumulation. Screenings, grain N content, malt extract, and indicators of malt modification were strongly influenced by total crop N yield or crop N concentration at anthesis. The level of mobilisation of N reserves to the grain during grain filling was also correlated with grain and malt quality, whereas the level of post‐anthesis N uptake had little effect. The best opportunities for manipulating malting quality were during early growth. Under dryland conditions there was less likelihood of excessive grain N concentration if a greater proportion of the grain N was derived from post‐anthesis N uptake. Management options for obtaining high yield and yet maintaining an acceptable grain quality for malting under non‐irrigated conditions include the possibility of N application up to anthesis. However, this would be recommended only if growth conditions allowed near‐maximum accumulation of DM in grain and the predominant source of DM for grain filling was from current photosynthate rather than stem reserve mobilisation.

Keywords:

• Hordeum vulgare L.
• nitrogen uptake
• malting quality
• nitrogen partitioning
• grain nitrogen
• malt extract
• micro‐malting